Renewable Energy--2008-EPS Project1-UPC

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EUROPEAN PROJECTSEMESTER

TITLE: Design and Layout of Renewable Energy Equipment for the New Roof of the

EPSEVG

AUTORS: Roman Dornberger, Ilgn Kahraman

SUPERVISORS: Jordi Segalas, Marcel Torrent

DATE: 16.06.2008


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TITLE: Design and Layout of Renewable Energy Equipment for the New Roof of the

EPSEVG

SURNAME:Dornberger NAME: Roman

SURNAME:Kahraman NAME: Ilgn

SUPERVISORS: Jordi Segalas, Marcel Torrent

QUALIFICATION OF THE PROJECT

TRIBUNAL

PRESIDENT SECRETARY VOCALA. Llorens J. Segalas C. Angulo

DATE OF PRESENTATION: 18.06.2008


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Vilanova i la Geltr, 16.06.2008

Statement of Authorship

We hereby certify that this report has been composed by ourselves, and describes our own

work, unless otherwise acknowledged in the text. All references and verbatim extracts have

been quoted, and all sources of information have been specifically acknowledged.

Roman Dornberger Ilgin Kahraman


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Table of Content

1

Table of Content

Table of Content......................................................................................................................... 1

Acronyms ...................................................................................................................................3Symbols and Equations ..............................................................................................................4

1 Abstract ................................................................................................................................. 11

2 Introduction ........................................................................................................................... 12

2.1 Renewable Energies ....................................................................................................... 12

2.2 Project Description......................................................................................................... 13

2.3 Problem Definitions ....................................................................................................... 14

3 State of the Art ...................................................................................................................... 163.1 Solar Thermal Systems for Domestic Water Heating .................................................... 16

3.1.1 Solar Thermal Collectors ........................................................................................16

3.1.1.1 Flat Plate Collector (FPC)................................................................................ 16

3.1.1.2 Vacuum Tube Collector (VTC)........................................................................ 18

3.1.1.2.1 Direct Perfused Collector (DPC)............................................................... 18

3.1.1.2.2 Indirect Perfused Collector (IPC).............................................................. 19

3.1.1.3 Thermosiphon Collector (TSC)........................................................................ 20

3.1.2 Equipment for the Solar Thermal System ...............................................................21

3.2 Photovoltaic Systems ..................................................................................................... 22

3.2.1 Photovoltaic Modules..............................................................................................22

3.2.1.1 Monocrystalline Module .................................................................................. 23

3.2.1.2 Polycrystalline Module .................................................................................... 23

3.2.1.3 Amorphous Module.......................................................................................... 24

3.2.2 Equipment for the Photovoltaic System.................................................................. 25

3.3 Showroom and Information Boards ............................................................................... 26

3.3.1 Idea of a Showroom ................................................................................................ 26

3.3.2 Basic Design of a Showroom.................................................................................. 26

3.3.3 Showroom and Information Board Examples......................................................... 27

4 Approach ............................................................................................................................... 30

4.1 Assumptions ................................................................................................................... 30

4.1.1 Hot Water Demand.................................................................................................. 30

4.1.2 Electrical Energy Demand ......................................................................................32

5 Analysis and Implementation................................................................................................ 33


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Table of Content

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5.1 Orientation and Inclination of the Panels ....................................................................... 33

5.2 Calculation of the Solar Thermal System ...................................................................... 37

5.2.1 Energy to Heat the Water ........................................................................................37

5.2.2 The f - Chart Method ............................................................................................. 38

5.2.3 Combining different Solar Collectors ..................................................................... 42

5.3 Calculation of the Photovoltaic System ......................................................................... 43

5.3.1 Isolated PV System ................................................................................................. 43

5.3.2 Grid Connected System Calculations...................................................................... 46

5.3.3 Combined System Calculations .............................................................................. 48

5.4 Design Specifications..................................................................................................... 48

5.4.1 Basic Layout of the Solar Thermal System............................................................. 48

5.4.2 Basic Layout of the Isolated Photovoltaic System.................................................. 53

5.4.3 Layout of the Information Boards ........................................................................... 55

5.4.3.1 Board for the ST System.................................................................................. 55

5.4.3.2 Board for the Isolated PV system..................................................................... 57

5.4.4 Layout of the ST and PV System on the Roof ........................................................ 58

6 Results ................................................................................................................................... 61

6.1 Main Results................................................................................................................... 61

6.2 Cost Calculation .............................................................................................................61

6.2.1 Costs and Amortisation of the Solar Thermal System ............................................ 61

6.2.2 Costs of the Photovoltaic System............................................................................ 63

6.3 CO2 Savings ................................................................................................................... 64

7 Conclusion............................................................................................................................. 65

List of Images and Tables ........................................................................................................ 68

Images .................................................................................................................................. 68

Tables ................................................................................................................................... 69

References ................................................................................................................................ 70

Appendices............................................................................................................................... 72


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Acronyms

3

Acronyms

CO2 Carbon Dioxide

CPC Compound Parabolic ConcentratorsAC Alternating Current

DC Direct Current

DIN Deutsche Industrienorm (German Industry Standard)

DN Nominal Diameter

DPC Direct Perfused (Vacuum Tube) Collector

EPANET Software that models the hydraulic and water quality behaviour of

water distribution piping systemsEPSEVG Escola Politcnica Superior dEnginyeria de Vilanova i la Geltr

FPC Flat Plate Collector

HTI Higher Technical Institute, Nicosia, Cyprus

IPC Indirect Perfused (Vacuum Tube) Collector

L008 Room number 8 of the electrical engineering lab in the EPSEVG



LED Light Emitting Diode

MS Microsoft

MUTEK Mula niversitesi Temiz Enerji Kaynaklar & Ar-Ge Merkezi

MW Megawatt

PV Photovoltaic

RE Renewable Energy

REE Renewable Energy Equipment

ST Solar Thermal

TSC Thermosiphon Collector

UPC Universidad Politecnica de Catalunya

VG 1-2-3 University building 1, 2 and 3 of the UPC in Vilanova I la Geltr

VTC Vacuum Tube Collector


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Symbols and Equations

4


Symbol Unit Description

CA m Aperture area of the collector

,1,2,C SA m Aperture area of the 1. FPC, 2. VTCs, S. System

IA m Usable surface to install a PV system

pA m Area to set up a PV cell with 100 per cent solar access

SA m Surface of the roof

TubeA m Area of the tube

a m Length of the roof

1a W / m * K Linear thermal loss coefficient

2a W / m * K Quadratic thermal loss coefficient

b m Width of roof

C Ah Capacity of battery

fuelC / kWh Basic energy / fuel price

SysC Price of the solar system

SySTC Price of the solar thermal system equipment

SyPVC Price of the PV system equipment

pc kJ / kg * K Specific heat capacity, water: 4,184 kJ / kg * K

D - Number of days autonomy

d % Fuel inflation in Spain in 2008

Tubed m Diameter of the tube

E Ah / day Electrical charge per day

1E Ah / day Charge loss per day

PE Ah / day Charge produced by one panel per day

TE Ah / day Total charge per day

RF % Collector heat removal factor

'R

F % Collector heat exchanger efficiency factor


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5

af - Annual solar fraction

mf - Fraction of the monthly heating load supplied by solar

energy

1/ 2mf - Fraction of the monthly heating load supplied by solar

collector 1 or 2

G W / m Standard incident global solar radiation on the collector

surface (1000 W/m)

IH W / m Instant solar radiation

. .H S P h / day Hourly Solar Peak

TH MJ / m * day Daily Solar radiation per square meter

=310

1* *3600

dn

kWh / m * month

mpI A Maximum power current of the PV panel

i % General inflation in Spain in 2008

L m Distance between the lowest points of two panels

Pl m Length of a panel

1,2,Sm& kg / s Mass flow in the 1. FPC, 2. VTCs, S. System

Cm& kg / s Mass flow in the collector

Pm kg Mass of a panel

Totm& kg / month Total mass of hot water needed per month

STN years Amortisation time of the ST system

cn - Estimated number of coffees per day in the cafeteria

dn - Number of days per month

Ln - Number of lamps in the room L008

mn - Estimated number of meals per day in the cafeteria

min - Number of PV modules installed

modn - Number of PV modules

pn - Estimated number of persons who will use the shower

paralleln - Number of PV panels connected parallel


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6

seriesn - Number of PV panels connected in series

P W Power of each lamp in the lab

mQ kJ Monthly needed energy to heat the water,

1 kJ = 1 kWs = 1* 610 GJ

1,2,SQ W Instant produced energy by 1. FPC, 2. VTCs,

S. System

TotQ kWh Total heating load per year

cR % Reduction of fully charged capacity of a battery

1,2, ,S coldT C Cold solar liquid temperature in the 1. FPC,

2.VTCs, S. System1,2, ,S hotT C Hot solar liquid temperature in the 1. FPC, 2. VTCs,

S. System

ambT C Ambient temperature

FauT C Temperature of the faucet water

HotT C Temperature of the hot water

PavT C Average panel operation temperature

refT C Reference temperature

Lt h Estimated working hours of the lamps in the room L008

Pt m Thickness of a panel

CV l Hot water demand for cafeteria

CcV l Hot water demand per coffee in cafeteria

Cm

V l Hot water demand per meal in cafeteria

mpV V Maximum power voltage of the PV panel

SV l Hot water demand for showers

SpV l Hot water demand per person in the shower

TotV l Total volume of hot water needed

mW Wh / month Monthly energy demand

dW kWh / day Daily energy demand


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7

pW Wh Maximum Energy produced by the grid connected PV

array per day

Pw m Width of a panel

X - Collector lossY - Collector gain

T K Difference between HotT and FauT

s, h Total number of seconds or hours per month

% Heat exchanger efficiency factor

- Performance of solar thermal collectors

0 - Optical efficiency of the solar panel

1,2,S - Efficiency of 1. FPC, 2. VTCs, S. System

W kg / l Density of water, 1 kg / l

( ) % Monthly average transmittance- absorptance product

( )n

% Normal transmittance- absorptance product

ur

m / s Velocity of fluid in the tubes of the ST system


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8

Equations

(01)Tot C S

V V V= +

(02) (( * ) ( * ))*C Cc p Cm m d V V n V n n= +

(03) * *S Sp p d

V V n n=

(04) * * *m L L d W n P t n=

(05) 0 1 2( )Pav amb Pav ambT T T T a a

G G

=

(06) * *Tot pQ m c T = &

(07) Hot Fau

T T T =

(08) TotTotW

Vm

=

(09) ( )'

1 * * * *CR

ref amb

R m

AF X a T T

F Q=

(10)( )( )

'

0 * * * * *cR

T d

R mn

AFY H n

F Q

=

(11)

( )

'

1

1

11 * 1

*

R

R

C P c

F

F a

m c

=

+ &

(12) ( ) ( ) ( )( )( )11,6 1,18* 3,86* 2,32*

100 Hot Fau ambC

amb

T T TXX T

+ + =

(13) 2 2 31,029 0,065 0,245 0,0018 0,0215m

f Y X Y X Y = + +

(14)

12

112

1

( * )m m

m

a

m

m

f Q

f

Q

=

=

=


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9

(15)

12

1 21

12

1

(( )* )m m m

ma

m

m

f f Q

f

Q

=

=

+

=

(16) 1,2, 1,2, 1,2, , 1,2, ,* *( )*1000S S p S hot S cold Q m c T T = &

(17) 1,2,1,2,,1,2, *

S

S

C S I

Q

A H

=

(18) mdd

WW

n=

(19) dmp

WEV

=

(20) 1*10

100

EE =

(21) 1T E E E = +

(22) . . *0,0239*0,0116T

H S P H =

(23) . . * IP mpE H S P=

(24) modT

P

En

E=

(25)

12

mod1

12m

mi

n

n ==

(26) 100* *T

c

E DCR

=

(27) *s

A a b=

(28) *2,71L l=

(29) *p p A L w=

(30)*60

100sI

AA


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10

(31) Ipp

AN

A

(32)

*( )ln

* * *1

ln1

Sys

a Tot fuel S

ST

C i d

f Q C Nd

i

=+

+

(33) (( * )*( * ))* . . .P series mp parallel mpW n V n I H S P=

(34) *mi series parallel

n n n=

(35) CTube

mA

u

=&r

(36)*4

TubeTube

Ad

=

(37)

*( )ln

* * *

1ln

1

Sys

a Tot fuel S

ST

C i d

f Q C N

d

i

=+

+


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1 Abstract

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1 Abstract

This report deals with the layout and design of a solar renewable energy system for the new

roof of the EPSEVG. It also outlines how local schools and educational centres will benefitfrom it. To provide domestic hot water for shower and cafeteria and the power for one room

in the VG 1-2-3 building of the university by using solar renewable energy equipment seems

to be a perfectly logical solution. The project has been divided into two parts: the first part is

the design of the solar thermal and the photovoltaic system. Design of solar systems involves

the evaluation of the equipment itself and energy needs. Photovoltaic systems are designed

provide electricity for the room L008 in the university. On the other hand, the second part is

to link the renewable energy equipment to the local studies. Therefore the visual layouts oftwo information points are designed. These boards show the structure of the solar thermal and

the photovoltaic system and screen the most important measured values in real time.

All the results of the project are generally useful for the reconstruction of the roof of the

EPSVEG and the implementation of renewable energy systems. The knowledge and

experience of using solar thermal and photovoltaic equipment is also useful for similar

projects in this region.


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2 Introduction

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2 Introduction

2.1 Renewable Energies

In the last years a worldwide increase of the use of renewable energy was recorded.

The reason for this is not only the drain on fossil fuel resources such as coal or oil but also the

global warming caused by the high emissions of Carbon dioxide which accrue when fossil

fuels are burned to produce usable energy.

This consecutive pollution of our planet caused a change of thinking and acting of the worlds

population. To decrease the worldwide CO2emissions caused by burning fossil resources the

energy production changes to the use of renewable energies. The main groups of renewable

energies are listed below:- Biomass and Bio fuels- Geothermal Energy- Water power like Hydro-, Tidal- and Wave power- Wind power- Solar power

In 2006, about 18 percent of the final global energy production came from renewable. Butonly 0,8 percent of the final energy consumption was provided by modern technologies, such

as wind, solar and ocean energy [01]. Until today a huge number of large scale renewable

energy projects and plants were founded worldwide. One of those plants is the 11 MW PS10

solar power tower in Seville, Spain, which is shown on image 1.

Image 1: PS10 solar power tower in Seville, Spain [02]


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To reduce the emissions of CO2, which is blamed in part for the global warming, the leaders

of the European Union reached an agreement in March 2007 that 20 percent of the nations

energy should be produced by renewable fuels by 2020 [01].

2.2 Project Description

This project deals with the reconstruction of the roof of the building VG 1-2-3 of the

EPSEVG. The old roof construction will be substituted by a renewable energy equipment

showroom, which should also be used to generate energy for the building itself.

One of the first steps of the project will be the dismantling of the old roof of the school.

Thereby, all the hazard materials which the roof contains now shall be disposed in a

sustainable way.

Afterwards the new design will be implemented to the building. This design will be directly

linked to the main objectives of the project like connecting the used renewable energy

systems to the building. With the connection of, for example, a solar thermal system the hot

water needs of the building could be covered. If a photovoltaic system is connected, the

produced energy can be used to power a number of rooms of the school, which will depend on

the size of the system. But also other objectives like accessibility for disabled people and the

use of non hazardous material should be taken into account.

The next step will be the implementation of the new roof to the local studies. Therefore

information points should be built. Those points shall show how a renewable energy system

works. It shall also measure important values of the equipment and the system in real time.

For the implementation of the renewable energy systems to the studies, they could be directly

linked to a computer in a laboratory or a training room.

A picture of the roof, which will be rebuilt, is shown in image 2.


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Image 2: Roof of the EPSEVG in 2008 [03] (left) and on Google Maps [04] (right)

2.3 Problem Definitions

This report shall develop the layout and the design of the renewable energy equipment for the

new roof of the EPSVEG. According to the local climatic conditions this report will only deal

with solar equipment and its implementation to the building.

In the first part of this report the existing solar systems and their components will bedescribed. The following chapter 5.1 will explain the evaluation of the most efficient

orientation and inclination of the solar thermal and photovoltaic panels. After that the hot

water and energy needs of the chosen rooms and facilities of the university will be calculated.

Together with the evaluation of the most efficient orientation of the panels the calculation of

the number of photovoltaic and solar thermal panels, which will be needed to cover the

demands, will take place. Regarding to those results the basic layout of the solar equipment

will be designed.The setup of the solar equipment on the roof will be directly linked to the technical conditions

of the building and to the solar access of the different areas on the roof. The solar thermal

equipment should be placed near to the facilities, where the hot water will be needed. The

setup of the photovoltaic equipment will also be specified in this part of the report.

For the layout of the solar equipment the roofs function as a showroom should be taken to

account. Therefore the accessibility of the solar equipment for students and visitors should be

guaranteed. Also information boards shall be used to show the most important measurements


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2 Introduction

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of the equipment and the working method of the solar systems. The next part of the report will

show the visual layout of the information boards for the two different systems.

In the last part of the report will deal with a cost calculation of the solar systems regarding to

the designed system.

A first draft of the new roof is shown in image 3.

Image 3: First draft of the new roof


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3 State of the Art

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3 State of the Art

3.1 Solar Thermal Systems for Domestic Water Heating

3.1.1 Solar Thermal Collectors

The solar collector field is the most important part of the solar thermal system. It is basically

made up of the solar thermal collectors, which transform solar energy into heat. There are

several solar thermal technologies available for different applications. The different types of

collectors are listed below:

- Flat plate collector- Vacuum collector- Thermosiphon collector system

A closer description of the three mentioned collector types is given in the next chapters.

3.1.1.1 Flat Plate Collector (FPC)

All the flat plate collectors consists a metal absorber in a flat rectangular and isolated housing.The absorber converts the sunlight into heat. This heat is transferred to the fluid that flows

through small tubes welded below the absorber. The fluid transports the absorbed heat to the

storage tank or consumer point. Just to capture as much solar energy as possible, some

absorbers are covered with a dark spectral- selective coating, which permits a high light

absorption capacity and a low thermal emissivity. The basic structure of a FPC is shown in the

image below. Also the collector is thermally insulated on its back and edges, and is provided

with a transparent cover on the upper surface. Two pipe connections for the supply and return

of the heat transfer fluid are fitted, usually to the sides of the collector. [05]


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Image 4: Sketch of a Flat Plate Collector (FPC) [05]

As shown in image 4 different area definitions are used in the manufactures literature to

describe the geometry of the collectors. This also applies to all the other solar thermal

collector technologies. The three different areas are described as follows:

- Gross area: Is the product of the outside dimensions, and defines for

example the minimum amount of roof area that isrequired for mounting.

- Aperture area: Corresponds to the light entry area of the collector, in

other words, is the area through which the solar radiation

passes to the collector itself.

- Absorber Area: Is the area of the actual absorber panel.

Todays flat plate collectors can reach efficiency up to 70per cent. That means that 70 per

cent of the sunlight, which hits the collector surface, can be converted into useable heat

energy. Some providers also indicate higher efficiencies for some of their collectors [06].


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3.1.1.2 Vacuum Tube Collector (VTC)

The vacuum tube collector (VTC) is the second type of collectors, which can be used to heat

water for the domestic use.

The basic working method of a VTC is the same as the one of a FPC. An absorber is used to

collect and convert the heat of the sun. The heat is transferred to a fluid, which flows trough

the tubes or heat pipes inside the glass cylinder. The applied absorbers of a vacuum tube are

either flat beside the absorbing tube or arched between two concentric glass tubes. Sometimes

also mirrors/CPCs (Compound Parabolic Concentrators) are used to reflect the light, which

missed the water containing tubes.

One advantage of a VTC is the isolation. Therefore a vacuum, which prevents the heat

transfer because of convection, is used [07]. Depending on the type of vacuum tube collector

the vacuum is in the one tube or in the space between two concentric glass tubes. The two

types of VTC are listed below.

- Direct perfused collector- Indirect perfused collector

3.1.1.2.1 Direct Perfused Collector (DPC)

This type of VTC is directly perfused by water or a special solar fluid. At first the fluid

streams down at the inside of a double- walled tube; also called Sidney tube. When

streaming up trough the outer space of the double- walled tube the fluid absorbs the heat from

the absorber.

A scheme of a direct perfused vacuum tube collector can be seen in image 5.


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Image 5: Direct perfused Collector with a flat absorber [08]

3.1.1.2.2 Indirect Perfused Collector (IPC)

This type of VTC contains a so called heat pipe. The solar fluid, mostly alcohol, in the heat

pipe absorbs the heat from the absorber and starts to vaporize when reaching a certain

temperature. The vapor streams up the tube to a small heat exchanger. With the heat exchange

from the vapor to the solar fluid, the alcohol starts to condense at the top of the heat pipe. The

liquid alcohol flows down the tube and the process starts again.

A scheme of an indirect perfused collector is shown in image 6.


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Image 6: Indirect perfused collector with heat pipe and flat absorber [08]

The efficiency of a todays vacuum tube collector can be compared with this of the FPCs. A

big advantage of a VTC is the water temperature, which can be reached. Some VTCs can

produce hot water with a temperature up to 450C, which can also be used for industrial

purposes. Another advantage of a VTC is the functionality in special weathers. Because of the

vacuum, which is used as isolation, a VTC has a higher performance in winter than a FPC

(assumption: both types of collector ice and snow free).

Finally, the energy yield per year of a VTC is only a little bit higher than of a FTC [07].

3.1.1.3 Thermosiphon Collector (TSC)

In warmer climates where it is safe to mount the storage tank outdoors, a simpler

thermosiphon arrangement can be used, as shown in image 7.

This design dispenses with the circulation pump. It relies on the natural convection of hot

water rising from the collector panel to carry heat up to the storage tank, which must be

installed above the collector. For a thermosiphon arrangement vacuum tube and flat plate

collectors can be used. Furthermore, no heat exchanger is needed because the heated water

circulates directly through the panel. Sometimes the storage tank also contains an electric

immersion heater for top-up and use on cloudy days.


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3 State of the Art

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Image 7 : Thermosiphon solar system with FPC [09]

The thermosiphon system can easily be used for domestic water heating. One disadvantage of

this system is the capacity of the water storage tank. If the hot water demand is too big a

separate storage tank must be used, which makes the thermosiphon redundant.

3.1.2 Equipment for the Solar Thermal System

In this chapter contains a brief descriptions of the common equipment used in solar hot water

systems. The components and their short description are listed below:

- Frames, Tracker: The Frames are needed to mount the panel

static with the most efficient inclination and

orientation or moveable.

- Water Pump(s): The pumps are needed to pump the

fluid to the panels.

- Heat Exchanger: The heat exchanger is needed to transfer the

energy of the panel fluid to the domestic water.

- Hot Water Storage Tank(s): The hot water storage tank(s) is used to store

the hot water.


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- Expansion Tank(s): The expansion tank(s) is needed to absorb

excess water pressure.

- Tubes: The tubes are needed to connect the solar-

thermal panels to the pump(s), heat exchanger(s)

and the hot water tank(s).

- Isolation Valve: The isolation valves are needed to isolate the

solar tank in case of a problem.

- Tempering Valve: The tempering valve is needed to mix hot

and cold water, if the hot water, which comes

from the panel, is too hot. It is situated at the very

end of the chain.

- Controls: The controls compare the heat sensor

readings from the collector and the storage tank

and switch the pump accordingly.

If all of the listed components will go into action depends on the use of the solar water heating

system.

3.2 Photovoltaic Systems

3.2.1 Photovoltaic Modules

A photovoltaic (PV) cell produces energy from the power of the sun. It is constructed from

two types of silicon, which when hit by solar energy, produce a voltage difference across

them, and, if connected to an electrical circuit, a current will flow. A number of photovoltaic

cells will be connected together in a "Module", and usually encapsulated in glass held a frame

[10]. To produce energy from the sun different types of photovoltaic cells are mostly in use

today. Those three types are listed below:

- Monocrystalline cells- Polycrystalline or Multicrystalline cells- Amorphous cells.


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The three mentioned types of solar cells combined in a module will be described in the

following chapters.

3.2.1.1 Monocrystalline Module

Monocrystalline material is also called single crystalline because the basic material produced

by growing one large crystal. The process to produce monocrystalline silicon is relatively

slow and energy intensive compared to processes used for other silicon based PV materials.

Therefore the principle advantage of monocrystalline cells is their high efficiency typically

around 15 per cent. Although, the manufacturing process required produce monocrystalline

silicon is complicated because of this monocrystalline cells in slightly higher costs than other

technologies.

A monocrystalline cell is shown in image 8.

Image 8: Monocrystalline Silicon Cells [13]

3.2.1.2 Polycrystalline Module

Polycrystalline silicon essentially consists of small grains of monocrystalline silicon. Solarcell wafers can be made directly from polycrystalline silicon in various ways. These include

the controlled casting of molten polycrystalline silicon into cube-shaped ingots which are then

cut, using fine wire saws, into thin square wafers and fabricated into complete cells in the

same way as monocrystalline cells.

Polycrystalline PV cells are easier and cheaper to manufacture than their monocrystalline

counterparts. But they tend to be less efficient because light generated charge carries can

recombine at the boundaries between the grains within polycrystalline silicon. However, it has

been found that by processing the material in such a way that the grains are relatively large


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3 State of the Art

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size, and oriented in a top-to-bottom direction to allow light to penetrate deeply into each

grain, their efficiency can be substantially increased. These and other improvements have

enabled commercially available polycrystalline PV modules to reach efficiencies from 10- 15

per cent [11]. A photovoltaic module made of polycrystalline silicon is shown in image 9.

Image 9: Polycrystalline Silicon Cells [13]

3.2.1.3 Amorphous Module

Amorphous silicon cells are composed of silicon atoms in a thin homogenous layer rather

than a crystal structure. Amorphous silicon absorbs light more layers rather than crystalline

silicon, so the cells can be thinner. For this reason amorphous silicon is also known as a thin

film PV technology. Amorphous silicon can be deposited on a wide range of substrates, both

rigid and flexible, which makes it ideal for curved surfaces and fold-away modules.

However, amorphous cells are less efficient than crystalline based cells, with typical

efficiencies from 5- 10 per cent [11], but they are easier and therefore cheaper to produce. In

image 10 an amorphous silicon cell is shown.

Image 10: Amorphous Silicon Cells [13]


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3 State of the Art

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3.2.2 Equipment for the Photovoltaic System

In this chapter contains a brief descriptions of the common equipment used in photovoltaic

systems. The components and their short description are listed below:

- Frames, Tracker: The Frames are needed to mount the panel

static with the most efficient inclination and

orientation or moveable.

- Inverter: The inverter is needed to convert the direct

current (DC) to an alternating current (AC).

- Converter: The converter is needed to convert a source

of direct current (DC) from one voltage level to

another (DC- DC- Converter).

- Charge Controller: The charge controller is needed to control

the charge level of the battery/-ies. If the

battery/-ies will run low the charge controller

switches to the normal grid of the building.

- Battery: The battery/-ies are used to store the

electricity produced by the photovoltaic cell(s)

- Cables: The cables are needed to connect the

photovoltaic equipment.

The use of the components listed above depends on the installed photovoltaic system.


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3 State of the Art

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3.3 Showroom and Information Boards

As mentioned in the project description the new roof with the renewable energy systems will

also be used as a showroom. This chapter will deal with the basic idea and design of ashowroom for renewable energy systems and show three examples of showrooms, which

already exist.

3.3.1 Idea of a Showroom

A showroom is defined as a [] large space used to display products for sale [] [12].

This shall also be one of the ideas for the new roof of the EPSEVG. Providers of solar thermal

and photovoltaic equipment should advertise their products on the roof of the university.

Therefore the companies can use the free space on the roof to set up and work with their

panels.

The other idea of this showroom is to show citizens, who are interested in this type of REE,

how the technology works. Therefore the systems have to be designed with a maximum level

of understandability. The showroom should display the different available types of ST and PV

panels and equipment.

Also the new room shall be used for teaching purposes.

3.3.2 Basic Design of a Showroom

The RE systems on the roof shall be designed with a maximum level of accessibility. This

will be an advantage for the visitors of the roof on the one hand and for repair and

maintenance on the other. Also the accessibility for disabled people should be taken to

account, when designing the layout of the renewable energy systems. The space between the

different panels should be accessible for people with wheelchair, walkers or other handicaps.

For a better understanding of the working method of the two solar systems information boards

shall be built and placed near the system itself. The boards shall show a sketch of the system

and important measurements in real time.


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3.3.3 Showroom and Information Board Examples

1. Technical University of Mining, Freiberg, Germany:

- Solar thermal system at the front of the students residence(image 11, left) to heat domestic water

- Information board at the entrance of the residence whichshows most important measurements (image 11, right)

Image 11: Students residence with VTC arrays (left), information board (right) [14]

2. Higher Technical Institute (HTI), Nicosia, Cyprus:

- Solar thermal equipment for domestic water heating- Solar plant connected to a lab, which is equipped with all

necessary instrumentation and control devices for remote

access, control, data collection and processing- Internet is used as the tool to make the lab accessible for

handicapped people, students, pupils and citizens around the

world

The following image shows the flat plate collectors on the roof of the HTI and the students

working in the lab.


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Image 12: FPC (left) and students working in the e- lab of the HTI (right) [15]

The second image of the e- lab shows a sketch of the whole system and the control system.

Image 13: Sketch (left) and control system (right) of the e- lab [15]


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3. Clean Energy Research & Development Centre (MUTEK), Mula, Turkey:

- Different types of PV modules on top of the library building.(image 14)

- Electrical output performance of modules is determinedunder operating conditions on the photovoltaic test site.

- Measured values: open-circuit voltage of the module, short-circuit current, maximum power output of the module,

voltage at maximum power, modules efficiency.

Image 14: Mula University Central Library roof with PV cells (left) and lab (right) [16]


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4 Approach

4.1 Assumptions

As described in the problem definitions the solar thermal and photovoltaic equipment shall be

connected to the building VG 1-2-3 of the EPSEVG.

According to the design of those two systems assumptions are going to be fixed in the

following two chapters.

4.1.1 Hot Water Demand

The solar thermal system will be used to heat water for the cafeteria, which is located in the

ground floor of the building. Also it will be connected the showers, which are going to be

built together with the reconstruction of the roof.

For the calculation of the hot water demand the following values have to be committed:

- Hot water temperature HotT - Faucet water temperature FauT for every month- Total Hot water demand per month

TotV

The value for the hot water temperature is estimated with:

60HotT C= .

The average values for the faucet water temperature are shown in table 1.

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Unit

FauT 9 10 11 12 14 17 19 19 17 15 12 10 [C]

Table 1: Average faucet temperature in Vilanova i la Geltr [17]

Furthermore, the total hot water demand can be calculated with the following equation;


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4 Approach

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Tot C SV V V= + (01)

whereinC

V andS

V are defined as the needed volume of hot water in the cafeteria (C

V ) and

the showers ( SV ) per month.

To calculate those volumes further estimated values are shown in table 2.

Cafeteria Shower

hot

water/coffeecoffees/day

hot

water/mealmeals/day

hot

water/personpersons days/month

CcV

in [l]c

n

Cm

V

in [l]m

n

Sp

V

in [l]p

n d

n

1 100 10 30 15 30 20

Table 2: Estimated values for cafeteria and showers [18]

The equations (02) and (03) show how to calculate the hot water demand of the cafeteria and

the showers.

(( * ) ( * ))*C Cc p Cm m d V V n V n n= + (02)

* *S Sp p d V V n n= (03)

The results of the two equations are:

8000c

V l=

9000SV l= .

According to equation (01) the total hot water demand, which has to be provided by the solar

thermal system, is

17000Tot

V l= .


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4.1.2 Electrical Energy Demand

The PV system is going to power the lightings of the room L008 of the electrical engineering

departments laboratory (L008, L009, L010). A sketch of the laboratory with its three rooms

is shown in image 15.

Image 15: Sketch of the electro technical laboratory

The following conditions are given for the lighting system of the room L008:

Number of Lamps: 12L

n =

Potency of each lamp: 58P W=

The working hours are estimated with 8L

t h= per day and 20d

n = days per month.

By using equation 04 the monthly energy demandm

W can be calculated.

* * *m L L d

W n P t n= (04)

111360 /m

W Wh month=


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5.1 Orientation and Inclination of the Panels

The orientation of the collector array must be south in order to capture as much solar energy

as possible. Sometimes, due to integration reasons for solar roof collectors, 20- 45 deviations

from the south are allowed depending on the geographical site of Spain. On the other hand,

the inclination angle of the solar collectors for installations that are working the whole year

depends basically on the latitude.

One of the first steps for this evaluation is to consider meteorological data from local

meteorological stations; in Catalonia the Energy Catalan Institute published the Solar Atlas of

Catalonia [19] in 2001 which provides the average daily radiation in this region; also theEuropean commission offers a website with radiation data for all Europe [20].

As shown in image 16 the average radiation in Spain differs between 1000 and

2000 / / kWh m year. For Vilanova i la Geltr and Barcelona the average radiation shown in

this image is about 1500 / /kWh m year.

Image 16: Yearly sum of global irradiation on a horizontal surface for Spain [20]


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The second step to evaluate the best orientation and inclination of a solar panel is shown in

image 17.

Image 17: Percentage of useable solar radiation depending on azimuth and latitude [05]

This graphic show which orientation and inclination of a solar panel is needed to capture the

highest percentage of the solar radiation. To reach 100 per cent the values have to be:

Orientation: 0

Inclination: 45.

Also it should noted that variations of 20 in the tilt angle and 45 in the azimuth,

practically do not have an effect on the annual irradiation that strikes solar collectors [05].

According to image 17 and the results listed above, the solar radiation data for Barcelonawhich can be found in the Solar Atlas of Catalonia can be evaluated. Therefore the variation

of the performance of solar thermal collectors can be calculated using following characteristic

performance equation [20].

0 1 2

( )Pav amb Pav ambT T T T a aG G

= (05)


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Most of the values, except the panel operating temperature and the ambient temperature, are

specific for each solar panel. The data for

0

Optical efficiency of the solar panel,

1a Linear thermal loss coefficient and

2a Quadratic thermal loss coefficient

is listed on the data sheet of each panel. The data sheets of the six chosen panels are attached

to this report as appendix 01 (CD). The value G is gauged with 1000 / W m for this

calculation.

The average panel operation temperature PavT can be estimated with following values.


PavT 35 35 35 35 35 45 45 45 45 35 35 35 C

Table 3: Average panel operation temperature per month

According to the Catalan Energy Institute [21] the monthly average temperature ambT in

Barcelona / Vilanova i la Geltr is listed in the following table.


ambT 11 12 14 17 20 24 26 26 24 20 16 12 C

Table 4: Monthly ambient temperature in Barcelona / Vilanova i la Geltr [21]

With this data the monthly performance of a solar panel can be calculated. Multiplying this

value by the monthly solar radiation results in the energy, which can be produced per month.

An example for this calculation is shown in table 5.


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Solar RadiationT

H in Barcelona

Orientation: 0 Inclination: 40Month

[MJ / m*day] [kWh / m*month]

Energy produced permonth [kWh / month]

Jan 0,593 12,44 107,122 63,567

Feb 0,595 14,88 115,733 68,824Mar 0,597 17,91 154,225 92,099

Apr 0,601 20,23 168,583 101,287

May 0,604 21,35 183,847 111,103Jun 0,597 21,7 180,833 107,989

Jul 0,600 21,69 186,775 111,993Aug 0,600 21,12 181,867 109,050Sep 0,597 19,37 161,417 96,394

Oct 0,604 16,43 141,481 85,500

Nov 0,600 13,47 112,250 67,307Dec 0,595 11,77 101,353 60,272

Table 5: Panel efficiency, monthly solar radiation in Barcelona and produced energy bythe SolarUK LaZer2 VTC

This table shows only one example of the energy production of a solar panel per month.

The calculations in the following chapter take place with six solar panels of two different

types. These panels are listed below.

- FPC: Agena Azur 6- FPC: JansenSchcoSol CH- FPC: Viessmann Vitosol 200-F type 5DI- VTC: AMK Collectra OPC 15H- VTC: Spring solar SK8 CPC- VTC: SolarUK LaZer2

With the data from these calculations, the values listed on the data sheets of the solar panels

and the solar radiation data the best orientation and inclination of a panel can be evaluated.

The results of this appraisal show the most efficient justification of a solar thermal panel in

this region:

Orientation: 0

Inclination: 40


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The efficiency of the solar thermal system could be expressed in terms of the fractional

energy savings and energy yield, which will be discussed in chapter 3 [05].

The maximum irradiation of a PV panel is achieved with following values:

Orientation: 0

Inclination: 35

5.2 Calculation of the Solar Thermal System

5.2.1 Energy to Heat the Water

This chapter deals with the calculations which are needed to dimension the solar thermal

system. With the assumptions made in chapter 4.1.1 a basis for the following work has been

established.

One of the first steps is to calculate the amount of energy which is needed to heat the water.

Therefore equation (06) is used.

* *m Tot p

Q m c T = & (06)

Where Hot Fau

T T T = , (07)

4,184 / *p

c kJ kg K = and

17000 /Totm kg month=& .

The total mass of needed hot water can be calculated as follows.

Tot

Tot

W

Vm

=& (08)

The results of equation (06) are subsumed in the table below. According to the monthly

difference in the faucet temperature, the energy to heat the water differs too.


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HotT 60 60 60 60 60 60 60 60 60 60 60 60 [C]

FauT 9 10 11 12 14 17 19 19 17 15 12 10 [C]

T 51 50 49 48 46 43 41 41 43 45 48 50 [K]

mQ 3,63 3,56 3,49 3,41 3,27 3,06 2,92 0,00 3,06 3,20 3,41 3,56 [GJ]

Table 6: Monthly values according to equation (06) and needed energy

The energy need in august is zero because the university is closed.

For further calculations the f - Chart method is used.

5.2.2 The f - Chart Method

The f - Chart is a correlation of the result of many hundreds of thermal performance

simulations of solar heating systems. The resulting simulation gives f , the fraction of the

monthly heating load supplied by solar energy as a function of two dimensionless parameters,

X the collector loss ratio and Y the collector gain ratio [22].

The first factor is related to the ratio of collector losses to heating loads and can be calculated

with following equation.

( )'

1 * * * *CR

ref amb

R m

AF X a T T

F Q= (09)

The second factor is related to the ratio of absorbed radiation and the heating loads. Equation

(10) is used to calculate Y .

( )( )

'

0 * * * * *cR

T d

R mn

AFY H n

F Q

= (10)

To compare the efficiency of the six panels mentioned in chapter 5.1, X and Y has to be

calculated for one square meter of solar panel. Therefore the equations (09) and (10) have to

be calculated with

1 C

A m= .


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The factor( )( )

n

is estimated with 1 in this case.

To calculate X and Y the factor that takes into account the efficiency of the heat exchanger

has to be calculated with following equation.

( )

'

1

1

11 * 1

*

R

R

C P c

F

F a

m c

=

+ &

(11)

For this equation the nominal mass flow of solar liquidC

m& inside the panel can be taken from

the data sheets of the panels. The value of the heat exchanger efficiency is estimated with

0,7.

If the solar thermal system is used to heat domestic water, the correction factorC

X has to be

implemented into the calculation of X . Therefore equation (12) is used.

( ) ( ) ( )( )( )

11,6 1,18* 3,86* 2,32*

100

Hot Fau ambC

amb

T T TX

X T

+ + =

(12)

The results of this equation are shown in table 7.


HotT 60 60 60 60 60 60 60 60 60 60 60 60 [C]

FauT 9 10 11 12 14 17 19 19 17 15 12 10 [C]

ambT 11 12 14 17 20 24 26 26 24 20 16 12 [C]

CXX

1,03 1,06 1,07 1,08 1,13 1,22 1,29 1,29 1,22 1,17 1,09 1,06 [ - ]

Table 7: Values and results of equation (12)

With those equations and estimated values the monthly solar fraction of the solar thermal

system can be calculated with the following equation.

2 2 31,029 0,065 0,245 0,0018 0,0215m

f Y X Y X Y = + + (13)


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The annual solar fractiona

f is calculated with equation (14).

12

1 12

1

( * )m mma

m

m

f Q

fQ

=

=

=

(14)

According to the [29] the annual solar fraction of a solar thermal system in the region of

Vilanova i la Geltr has to be bigger than 0,7 or 70 per cent.

To compare the efficiency of the six panels the results of all those equations are evaluated

graphically.

Image 18: Annual solar fraction per square meter of panel

This image shows the reachable annual solar fraction per square meter of the six chosen

panels.

According to this graph the suitable collector for the purpose of this project can be chosen.

After that the solar fraction for the selected panel is calculated again with the f - Chart

method. This time the equation for X and Y takes place with the true aperture area CA of the

collector.

The result of the second f - Chart calculation is shown in image 19.


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Image 19: Annual solar fraction per panel

This graphic shows which annual solar fraction can be reached according to the number of

installed panels in the system. For the following calculations of the solar thermal systems the

Viessmann Vitosol 200-F type 5DI FPC and the SolarUK LaZer2 VTC have been chosen.

The values for the annual solar fraction are subsumed in table 8.

Collector type Number of Collectors af

Agena Azur 6 4 0,71

Jansen SchcoSol.CH 4 0,76Viessmann Vitosol 200-F Typ 5DI 2 0,76

AMK-Collectra OPC 15H 5 0,76Spring Solar SK-8 CPC 8 0,74

SolarUK LaZer2 5 0,78

Table 8: Collector type, number and annual solar fraction

The equations mentioned in this chapter can be viewed in the MS Excel file F-CHART-

DATABASE+CALC_Panel which is attached as appendix 01 (CD).


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5.2.3 Combining different Solar Collectors

For showroom purposes different types of solar thermal collectors shall be installed. With

using flat plate and vacuum tube collectors in one system only one final calculation for the

annual solar fraction of the system is added. This equation, which is shown below, also takes

into account, that both collector types provide energy to heat the water.

12

1 21

12

1

(( )* )m m mm

a

m

m

f f Q

f

Q

=

=

+

=

(15)

The result of this equation is an evaluation of the solar fraction with different numbers of FPC

or VTC. An example for an evaluation with the FPC Viessmann Vitosol 200-F type 5DI and

the VTC SolarUK LaZer2 is shown in table 9.

Table 9: Annual solar fraction with FPC and VTC in the system

This table shows that with one collector of each type the minimum solar fraction of 0,7 for

the region of Vilanova i la Geltr can not be reached. With two Viessmann collectors theannual solar fraction is almost one, which means that the system is oversized. The

combination of one Viessmann and two SolarUK collectors is, according to the purpose, one

feasible and well dimensioned solution.

Number ofViessmann

Vitosol 200-F Typ5DI

SolarUK LaZer2af of the

system

1 1 0,692

1 2 0,854

2 1 0,966


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5.3 Calculation of the Photovoltaic System

5.3.1 Isolated PV System

This chapter deals with the calculations which are needed to dimension the isolatedphotovoltaic system.

With the assumptions made in chapter 4.1.2 a basis for the following work has been

established. All calculation used in this chapter refer to the book Energa Solar Fotovoltaica

[23]. Furthermore all the calculations for the PV system take place with the Atersa A-214P

panel. The reason for that decision is to involve a Spanish PV manufacturer in this project.

One of the first steps is to calculate the daily energy need. Therefore the monthly needed

energy is divided by the number of working days per month dn , which is in this case estimatedto 20 days.

md

d

WW

n= (18)

The result of this equation is a daily energy demand of

5568 /dW Wh day= .

This value is used to calculateE, the necessary amount of electrical charge per day.

d

mp

WE

V= (19)

With the maximum power voltagemp

V of an Atersa A-214P panel, which is 29,48 V ,

equation (19) gives the following result:

188,87 / E Ah day= .

Furthermore the following equation is used to implement the charge loss, which is estimated

with 10 per cent in this case.


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1

*1018,89 /

100

E E Ah day= = (20)

The total charge can be calculated with following equation.

1 207,8 /T E E E Ah day= + = (21)

The next step is to calculate the hours solar peak, which depend on the monthly solar

radiation.

. . *0,0239*0,0116TH S P H = (22)

The results of the last calculation are listed in the following table.

Table 10: Monthly solar radiation and hours solar peak

These values are needed to calculate the ampere hours which can be produced by the panel

every day. Therefore the following equation is used.

. . * IP mp

E H S P= (23)

The maximum power current mpI of the Atersa A-214P panel is fixed with7,26 A .

Dividing the total charge TE by the ampere hour produced per day by one panel results in the

number of PV modules.

modT

P

En

E= (24)

This number is different every month, because the calculation is directly linked to the monthly

solar radiation. The results of equation (23) and (24) are listed in the table 11.


TH 11970 14520 17770 20450 21900 22430 22340 21480 19360 16130 13010 11280 kWh/m2

. . .H S P 3,32 4,03 4,93 5,67 6,07 6,22 6,19 5,96 5,37 4,47 3,61 3,13 h/day


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PE 24,1 29,2 35,8 41,2 44,1 45,1 45,0 43,2 39,0 32,5 26,2 22,7 Ah / day

TE 207,8 207,8 207,8 207,8 207,8 207,8 207,8 207,8 207,8 207,8 207,8 207,8 Ah / day

mn 8,6 7,1 5,8 5,0 4,7 4,6 4,6 4,8 5,3 6,4 7,9 9,2 -

Table 11: Ampere hours produced, needed and resulting number of modules

Averaging mn results in the number of panels to be installed.

12

mod1

12m

mi

n

n ==

(25)

To power the lighting in the room L008 of the electrical lab six Atersa A-214P panels need to

be installed in an 24 V array with two series and three in parallel. If the energy produced by

the modules is not used in the lab it is stored in batteries. Therefore the number of batteries

and their capacity has to be calculated. To evaluate the capacity needed, following equation is

used.

100* *T

c

E DCR

= (26)

The number of autonomy days D is estimated with three. Also the natural lifetime of a

battery is usually defined as when the fully charged capacity is reduced to 70 per cent. This is

a permanent loss of 30 per cent of the capacity because of cycling and age. According to that

cR is estimated with 70 per cent.

Equation (26) shows, that six Atersa A-214P panels need 890,40 Ah battery capacity. In thiscase four Atersa Monobloc Opz-Solar 280 batteries with a capacity of 260 Ah each are

sufficient. The Atersa batteries have been chosen because of their long life capacity and the

matching provider.


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5.3.2 Grid Connected System Calculations

This chapter deals with the calculations which are needed to dimension the grid photovoltaic

system.

One of the first steps is to calculate the surface area of the roof.


*S A a b= (27)

with: 28,8a m=

12,0b m=

The surface area of the roofS

A is 2345,6 m .

Also the physical characteristics of the chosen Atersa panel have to be considered. They are

shown in table 12.

Atersa A-214P Unit

Total length Pl 1,645 mTotal width Pw 0,990 m

Total thicknessP

t 0,050 mWeight

Pm 20 kg

Table 12: Physical characteristics of the Atersa A-214P

To cover a maximum area with PV modules on the one hand, and guarantee 100 per cent solar

access on the other the distance between the lowest points of the modules must be calculated.


*2,71PL l= (28)

The results of this equation shows that 4,45 m distance are needed to guarantee 100 per cent

solar access.

To set up one panel the areaP

A , which is calculated with following equation, is needed.


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5.3.3 Combined System Calculations

The combined photovoltaic system also powers facilities of the building. The energy which is

not used for the facilities is injected to the public grid system.

To calculate the energy injected to the public grid is calculated by subtracting the daily energy

demand of the chosen facility (in this case lab L008) from the energy produced by the grid

connected array. The calculation is shown below.

Grid P d W W W= (35)

5.4 Design Specifications

5.4.1 Basic Layout of the Solar Thermal System

With the results of the calculations in chapter 5.2 the solar thermal system can be designed.

The circuits for the FPC and the two VTCs have to be combined in one system. To supply

the collectors with solar liquid a pump must be installed in every circuit. To prevent a

breakdown of the whole system each circuit needs to have an expansion tank. At the outtakeof every collector a temperature sensor has to be installed. The recorded values are

transmitted to a regulator, which controls the pumps in the system. Before the heated liquid

runs through the heat exchanger the two circuits are combined. To ensure that the hot liquid

flows in the right direction, one way valves are used at the points where the two circuits are

combined or split up. The two collector circuits are hydraulically balanced, what means that

flow regulation valves are not needed. The described equipment belongs to the primary circuit

of the solar thermal system. The second circuit is comprised by a pump, a tank and the heat

exchanger, which is also part of the primary circuit. The size of the tank depends on the daily

hot water need that has to be covered.

A layout of the whole solar thermal system is shown in image 20.


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Image 20: Primary and secondary circuit of the solar thermal system

A MS Visio file of this layout is added to this report on appendix 01 (CD).

The meanings of the labels shown in this image are listed below.

R-XXX tubesP-X pumps

V-XX one way or hand regulated valve

V-DX degassing valve

V-HP high pressure security valve

W-X heat exchanger

B-X storage, expansion tanks

TEIR-XXX

temperature sensorsC-X controller

The labels are chosen according to the DIN 19227-1.

The next step is to calculate the diameter of the tubes. At first the tube for the circuit of the

Viesmann FPC is calculated with following equation.

CTube

m

A u=

&

r (36)


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The velocity ur

in this circuit is estimated with 1,5 /m s . The nominal flow inside the

collector Cm& is 200 /l h or55, 55*10 / m s . This value is listed on the data sheet of the

Viessmann collector. With the result of equation (37) the diameter of the tube Tubed can be

calculated.

*4Tube

Tube

Ad

= (37)

This equation results in a diameter for the circuit of the FPC of 36,87*10Tube

d m= , which

are 6,8 mm . According to the nominal diameter of tubes (DN) a DN 8 tube with 8 mm inside

diameter is chosen. With this tube diameter a flow of 1,1 /m s in system is realized, which is

technically feasible.

The calculation of the tube diameter for the VTC circuit takes place in the same way. The

velocity is estimated with 1,5 /m s . The two vacuum tube collectors are connected parallel in

the system, what means that the flow in this part is 90 /l h or 52, 5*10 / m s . With those

values and the equations (36) and (37) a tube diameter of 5,4 mm is calculated. By using a

DN 6 tube a flow of 0,88 /m s is realized. For a solar thermal system the flow in the tube shall

be between 1,0 and 2,0 /m s inside the building and between 1,0 and 3,0 /m s outside;

higher velocity causes noise. This combination of flow, velocity and tube diameter is not

feasible. By using the same velocity in the circuit of the FPC and the VTCs flow regulation

valves are not needed. To minimize the quantity of different materials used for the ST system

the DN 8 tube is also going to be used for the circuit of the VTCs. With a velocity of 1,1 /m s

and an inside tube diameter of 8 mm a flow of 200 /l h in the circuit of the two VTCs canbe calculated with equation (36) and (37).The data sheet of this VTC shows a nominal flow

rate of 45 /l h and a maximum flow rate of 150 /l h per collector. By using the DN 8 tube for

the VTC circuit the flow of 100 /l h is technically feasible.

To evaluate the pumps for the ST system the EPANET software is used [24]. This software

allows to add characteristic curves for the collectors and pumps and to dimension the whole

system. The EPANET software during the evaluation of the system is shown in the two

images on the following pages.


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Image 21: Evaluation of the equipment for the primary circuit of the ST system with

EPANET [24]

The values shown at the tubes in the system is the flow inside the tube in liters per second.

The values at the junctions show the pressure in meter.


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Image 22: Evaluation of the equipment for the secondary circuit of the ST system with

EPANET [24]

In this evaluation all important values have been considered. The equal lengths of parts of the

tube system have been estimated as follows.

- One way valve: 1,86 m

- 90 curve: 0,25 m

- T- junction: 2,52 m

- Heat exchanger: 2,94 m

The evaluation of the pumps gave the following result.

Primary circuit: FPC Grundfoss Solar UPS 25-60

VTC Grundfoss Solar UPS 15-80

Secondary circuit: Grundfoss Solar UPS 25-40

With the chosen layout and equipment solar thermal system is technically feasible.


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5.4.2 Basic Layout of the Isolated Photovoltaic System

The layout for the isolated photovoltaic system with six Atersa 214P PV panels is shown in

image 23. This image also shows that they are connected in a 24 V array with two panels in

series and three parallel. The six panels are controlled by a Steca-Power 4055 regulator. This

regulator is the perfect solution for the chosen installation of the PV modules (two in series,

three parallel), because it uses 82 V maximum voltage and 55 A maximum current.

Furthermore the energy produced will be directly used or stored in four long-life monobloc

Atersa Opz-Solar 280 batteries. The energy produced by the photovoltaic array is inverted

from direct to alternating current with a Sunny Boy Sb1700 DC-AC inverter before its use in

the lab L008 of university building. This inverter reaches an effectiveness of almost 92 per

cent [25].

Image 23: Layout of the isolated PV system

A MS Visio file of this layout is added to this report on appendix 01 (CD).


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The labels used in this image are explained below. Those labels are not standardized.

R-XX Steca Power 4055 regulator

B-XX Four Atersa Opz Solar 280 batteries

I-XX Sunny Boy Sb1700 DC-AC inverter

Cables and Six Atersa A-214P PV modules

The selected inverter has been chosen with the Sunny Design software [25]. This software

allows selecting the type and number of PV modules, the region where they are used, the

inclination and the orientation. In the second step cables and a suitable inverter can be

selected out of a list. A screenshot of the evaluation with the Sunny Design software is shown

in image 24.

Image 24: Evaluation of the equipment for the isolated PV system with Sunny Design

software

With the chosen equipment this system is technical feasible.


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5.4.3 Layout of the Information Boards

The information boards will be used to explain the working method and the structure of the

two installed systems to the visitors on the roof. Therefore the boards are designed clearly and

with a maximum level of understandability. All components drawn on the board will be well

arranged and the measured values will be screened on small displays.

The following two chapters will show and describe the basic layout of the information boards

for the solar thermal and the isolated photovoltaic system.

5.4.3.1 Board for the ST System

The information board for the solar thermal system shows the image of the installed solar

water heating system with one FPC and two VTC. According to the temperature of the solar

liquid the tubes are coloured in red for the hot water and blue for the cold water.

An image of the information board of the ST system is shown below.

Image 25: Information board for the ST system


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The following values of the system are screened on the board:

- Cold water flow [l/h] of each circuits- Sum of the hot water flow [l/h] of both circuits- Cold water flow [l/h] to the tank- Collector intake temperatures [C] of all collectors- Collector outtake temperatures [C] of all collectors- Hot water temperature inside the tank [C]- Solar radiation [W/m]- Ambient temperature [C]

Small lamps or LEDs on the board are indicating if the pumps are working. In the right

corner of the board the instant production and efficiency of the FPC (Panel 1), the VTCs

(Panel 2) and the system is shown. Furthermore, the systems energy production of the last

day, week, month and year is listed.

A MS Visio file of this board is attached to this report on appendix 01 (CD).

To display the values on the board calculations have to take place. The instant production of

the panels and the system can be calculated with equation (16).

1,2, 1,2, 1,2, , 1,2, ,* *( )*1000S S p S hot S cold Q m c T T = & (16)

By relating this energy to the surface and dividing it by the solar radiation the efficiencies can

be calculated. Therefore the following equation is used.

1,2,

1,2,,1,2, *

S

S

C S I

Q

A H

= (17)

To show the values for the produced energy of the last day the instant production has to be

recorded every hour. At the end of the day 24 values are recorded, which can be summed up

to the energy produced on the last day. The calculation of the production of last week, month

and year is similar.


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5.4.3.2 Board for the Isolated PV system

The information board for the isolated photovoltaic system shows the image of the installed

system with an array of six PV panels. Small lamps or LEDs at the switches indicate if the

panels are connected to the regulator. At the second switch the lights indicate if the batteries

are getting recharged.

An image of the information board of the ST system is shown below.

Image 26: Information board fort he isolated PV system

The following values of this system are screened on the board:

- Current produced by PV array [A]- Voltage produced by PV array [V]- Battery Load: Current [A] and Voltage [V]- Solar radiation [W/m]- Ambient temperature [C]


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solar thermal system is situated on the roof; so visitors and student can explore how this

system works.

The grid connected system has no limited number of installed PV modules. Only the

accessibility for visitors on the roof has to be taken into accout. As calculated in chapter 5.3.2

46 Atersa panels can be installed on the roof to guarantee 100 per cent solar access and

accessibility. The layout of the grid connected PV system and the ST system can be seen in

the following image.

Image 28: ST and grid connected PV system on the roof

According to this image 48 Atersa modules can be installed on the roof. The free space in the

middle of the roof between the PV arrays can be used as walking way. The information

boards are again situated next to the systems.

Furthermore another option for the grid connected PV system exists. In this case all PV arrays

can be installed on frames, which will raise the arrays about 2 or 3 meter from the ground of

the roof. In this case more PV modules can be installed while the accessibility is still

guaranteed. An image of this idea is shown below.


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Image 29: ST and raised grid connected PV system on the roof

In this case about 75 Atersa PV modules can be installed on the roof. The information board

for the PV system is situated under the PV arrays.The three presented layouts are ideas of the authors of this report. The layout which is going

to be built during the further progress of the whole project is not specified.

A MS Visio file of every layout is attached to this report as appendix 01 (CD).


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6 Results

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6 Results

6.1 Main Results

The F- Chart calculation for the solar thermal system shows that one Viessmann 200F 5DI flat

plate and two SolarUK LaZer2 vacuum tube collectors are needed to heat the 17000 l water

per month for the cafeteria and the showers. Each type of solar thermal panel has its own

water circuit, which is hydraulically balanced. Both circuits are connected to a heat exchanger

where the heat of the solar fluid is transferred to the service water. With the whole system an

annual solar fraction of 0,854 can be reached.

To power the lighting of the electrical engineering lab 008, six polycrystalline Atersa 214P

panels are used. They are connected in an 24 V array with two panels in seriesand three in

parallel. The energy produced will be directly used or stored in four long-life Atersa batteries.

To control the system, a regulator from Steca is used. The energy produced by the

photovoltaic array is inverted from direct to alternating current before its use in the lab.

6.2 Cost Calculation

6.2.1 Costs and Amortisation of the Solar Thermal System

The costs of the ST system contain only the basic material for the installation and the

regulation of the system.

A table with the parts of the system, number of items and prices is shown below.


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6 Results

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No. Price Sum Ref.Collectors Viessmann Vitosol 200F 5DI - FPC 1 pc. 1.596 1.596 [26]

SolarUK LaZer2 - VTC 2 pc. 898 1.796

Frames 2 pc. 71 142 [27]

Pumps Grundfos Solar UPS 25-40 1 pc. 84,16 84,16 [28]Grundfos Solar UPS 25-60 1 pc. 94,35 94,35 [28]Grundfos Solar UPS 15-80 1 pc. 108,67 108,67 [28]

Heat Exchanger 1 pc. 427 427 [27]Tubes 37 m 10 370

T Junction 2 pc. 20 40 [27]Valves 4 pc. 10 40

Tank 800l Tank 1 pc. 1.867 1.867 [27]

Controler Deltasol M 1 pc. 755 755 [27]TempSensor 4 pc. 25 100

Expansion Tank 2 pc. 22 44 [27]

Table 13: Prices of the equipment for the solar thermal system (excl. VAT)

The price of those items without any reference is estimated. Also the working hours for the

installation of the system are not considered.

Summing up the listed equipment gives the price of the whole system, which is

7464 SysC = .

With these costs the amortisation time of the solar thermal system can be calculated.

Therefore the following equation is used.

*( )ln

* * *

1ln1

Sys

a Tot fuel S

ST

C i d

f Q C N

di

=

+ +

(37)

The values listed below have been researched for Spain in the year 2008.

- general inflation in Spain [30]: 4,5 %i = - fuel inflation in Spain [30]: 14 %d = - basic energy / fuel price [30]: 0,095576 /kWhfuelC =


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The efficiency of the systemS

is estimated with 70 per cent.

According to these values and equation (37) the amortisation time is 9,176 years .

6.2.2 Costs of the Photovoltaic System

The costs of the PV system contain the equipment for the installation of the system.

Therefore, the price for a PV system is estimated with 9 per installed PkW . The used

equipment is listed in table 14.

Isolated systemequipment names

Isolated system equipmenttypes

Isolated systemequipment numbers

Pv modules Atersa A-214P 6

Inverter Sunny Boy SB 1700 1

Batteries Atersa Opz-Solar 280 4

Regulator Steca power 4055 1

Cables - -

Table 14 : Installation of PV cells equipment name and number

The price of the whole system depends on the produced energy. Six Atersa A-214 panels can

produce 1284,1 /P

kW year.

The price of the whole system, which is calculated with equation (38), is shown below.

1284,1*9 = 11556,9 SyPV

C =

The working hours for the installation of the system are not considered.


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6.3 CO2 Savings

According to the one of the goals of this project the chosen facilities of the university shall be

powered in a more energy efficient way. With the installation of the solar thermal system thenormal water heating system, which is powered by gas, is supported. The isolated PV system

saves energy by powering the room L008 of the lab.

Before the two RE systems are installed the water heating system was powered by gas. The

electricity for the lighting in the lab was taken from the grid. For the use of electricity from

the grid and gas the CO2 emission is, referring to Energia Solar Trmica [21], estimated with

following values.

Gas: 20,201 /kg CO kWh

Electricity: 20,264 /kg CO kWh

According to table 6 in chapter 5.1 the yearly produced energy to heat the water is

12

m=1

* 31,21 / 8668,1 / a m f Q GJ year kWh year = = .

To power the lighting in the lab the following yearly amount of energy has to be produced.

*11 1224,96 /m

W kWh year =

The monthly energy needed is multiplied by eleven, because in august the university is

closed; there is no energy needed to power the lightings.Multiplying the CO2 emissions per kilowatt-hour with the energy produced every year results

in the not emitted carbon dioxide. The savings for the two systems are listed below.

Solar thermal: 22041,25 kg CO /year

Photovoltaic: 2323,39 kg CO /year

In sum 22364,64 kg CO can be saved per year, by installing the two solar systems.


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7 Conclusion

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7 Conclusion

After an introduction to renewable energy systems in chapter two the outlines of the project

were presented. According to this the problems to be solved during this report were defined.The third chapter dealt with the state of the art of solar thermal and photovoltaic systems. The

functionality of the ST and PV panels, provided on the market, and their equipment is also

presented in this chapter. Besides that the objective of a showroom is explained and three

examples illustrate the functionality and the aim of showrooms with information points. In the

fourth chapter assumptions for the layout and the design of the two systems are made. This

chapter establishes the basis for the fifth chapter. The first step of this chapter was the

evaluation of the most efficient orientation and inclination of the two solar systems. Withthose values and the energy demands for the solar thermal and the photovoltaic system the

two systems are laid out and designed. At the end of this chapter the visual layout of the

information boards and the arrangement of the two systems on the roof are designed. In the

sixth chapter the main results are summed up. Besides that the cost calculations for the two

systems are made. At the end of this chapter the CO2 savings obtained trough the installation

of the two solar systems is calculated.

The two designed solar renewable energy systems are both technically feasible. The

evaluation of the orientation and inclination shows, that an orientation of 0 south is the most

efficient for solar thermal and photovoltaic elements. The best inclination for a ST collector is

40. With those values and the information from the data sheets of the solar thermal collectors

the monthly perf

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Renewable Energy--2008-EPS Project1-UPC