Renewable Energy Applications Grid-Connected PV System in Building

8/2/2019 Renewable Energy Applications Grid-Connected PV System in Building

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RENEWABLE ENERGY APPLICATIONS,GRID-CONNECTED PHOTOVOLTAIC SYSTEMS IN BUILDINGS

Panom Parinya

The Joint Graduate School of Energy and Environment , King Mongkuts University of Technology Thonburi, Bangkok, Thailand

Abstract: To assessment the valuable of renewable energy, Photovoltaic (PV) systems in buildings haveto consider the clearly parameters for comparison. These acceptable parameters are Energy Pay-BackTime (EPBT), Life-cycle CO2 emission and Cost of energy. In term of energy, the energy requirement forPV module production process will be considered first, then the comparison of EPBT between each typeof PV systems are presented. During the manufacturing of PV module and balance of systems cause emitthe pollution gas such as CO2, SO2 and NOx. Typically, all of energy technologies can cause the CO2emission, therefore this paper will present the comparison how different of CO2 emission of eachinteresting types of PV systems and renewable energies.

After that, the problems and barriers of PV systems especially, PV systems in buildings will beoffered for the understanding of this kind of PV technology. The last one is the considering of progressand potential in future of PV systems in buildings that illustrate the challenge of renewable energytechnology for the next generation.

1. INTRODUCTION

At present, energy deficient and climate fluctuation problems become obviously occur and affect tohuman being. Mostly energy used come from fossil fuel, the carbon based consistent that mainly causethe previous problems. Therefore, non-carbon based energy or sustainable energy has been developed andapplied for resolving these problems. Renewable energy is the one that the best solution that source ofenergy can sustain ecosystem and sufficient for the next generation.

All of renewable energy in the universe, the most imperative and greatest is solar energy. For theearth, solar energy plays a role as the driver of all activities both direct and indirect way. From thestudying of solar radiation show that average 1000 watts per square meter that the earth ground receive

from the sun, compare with energy consumption of human that average 2 kilowatts per person [1]. If assumethat all of solar energy can be used, so only 2 square meter per person that enough for each one. Reality,only 20 percents or below that we can utilize from solar energy.

One of the technology that convert solar energy for human use is called Photovoltaic (PV) , morethan 160 years that photovoltaic effect was discovered [3]. PV effect can change the solar energy intodirect electricity. By the characteristics of semiconductor, photons from light of a suitable wavelength fallwithin the p-n junction, they can transfer their energy to valence electrons in the material, thus promotingthem to a higher energy level or excited state that electrons become free to conduct electric current. Withthe different production technology and substrate of semiconductor, type of PV cell can be divided tomono-crystalline silicon, polycrystalline silicon and thin film or amorphous silicon. From these PV cellsare connected together to PV module. After that PV modules and other components such as converters areconnected together to the PV system.

There are several categories of PV system using now such as grid-connected, off grid and stand alonePV system but the most popular is grid-connected PV system especially, the system in building [2]. Eventhough there are not release emission during operating but they use energy for their manufacturing andlead to emit pollution as well. Furthermore the low efficiency converting energy and high cost of PV cellstill be problem in order to considering until now.


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2. PARAMETERS FOR PHOTOVOLTAIC SYSTEMS ASSESSMENT AND COMPARISON.

By the concept of renewable energy, environment impact and energy source sustainability areregarded together to asses that kind of energy technology. PV system technologies do not cause emissionsduring operation, but they do cause emissions during manufacturing and possibly on decommissioning.Because of energy using both thermal form and electrical form during manufacturing, we need tocompare the energy use in production process of all equipments with the energy gain from the PV system.

The results will indicate the useful and valuable for decision further.For environment impacts that are pointed to CO2 (carbon dioxide) emission mainly. The less CO2

emission means the friendlier and prefer for environment and human being. Due to the different ofsubstrate or component and production process that be varied by the type of PV system can lead to differlevel of energy use and CO2 emission. The several parameters that be suggested for life-cycle assessment(LCA) are

1) Energy Pay-Back Time (EPBT): The energy pay-back time of a PV system (in years) inwhich the energy input during the module life-cycle is compensated by electricity generatedwith the PV module. The EPBT depends on several factors, including cell technology, PVsystem application and irradiation.

2) Life-cycle CO2 emission: CO2 mitigation potential of PV systems are the result of

simplified form of LCA use to give the first indication of environmental aspects. Theoperation of PV power system does not involve the combustion of carbon-containing fuelsbut indirect emission of CO2 occurs in other stages of the life-cycle of PV power systems.

3) Cost of energy: Even though LCA does not include the economic term but we cannotneglect the consequence from economic system because this will become main markerchoosing energy technology for worldwide. So, taking into account to cost of energy andpotential of price are required.

To compare the useful of each type of PV systems, these 3 terms above are the main indicators forassessment. However, other factors such as energy requirement, lacking of materials, greenhouse gasemission, health, safety, economic aspects and environmental aspects and etc. should be considereddepend on the level of impacts.

3. LIFE-CYCLE ANALYSIS ASSESSMENT OF PV SYSTEMS IN BUILDING.

3.1Energy requirement for PV modules productions.

In this paper, the three main types of PV cell are concerned these are mono-crystalline silicon,polycrystalline silicon and thin film type: amorphous silicon. These types of PV technology are themostly commercial shared about 34.6%, 50.2% and 8.9%, respectively [2].

From the study of Kasuhiko Kato [5], each type of PV cell has different production technique andsubstrate that lead to require the different energy production. This paper will be described some of

concerned information.

The mono-crystalline silicon (c-Si) PV module (12.2% efficiency STD)The production of the c-Si PV module has main 5 processes as be shown in figure 3.1-1. At first thequartz (SiO2) or raw silica is baked with high temperature about 1200 degree Celsius result themetallurgical (MG-Si) and then trichlorosilane (SiHCl3) is produced from MG-Si. Second process,SiHCl3 reacts with H2 in a large-scale of electric furnace at 1200 degree Celsius result the poly-Si andsilicon tetrachloride (SiCl4). Third process, with the Czochralski (Cz) process, the poly-Si is molten andpoured into a silica crucible. At around 1400 degree Celsius a c-Si ingot is pulled up and cooledspontaneously. Both top and bottom of the ingot are cut off as so called off-grade Si that about 15-20percents of weight of the ingot. Then off-grade Si is supplied to the Cz process again and result the c-Siingot which is then sliced into wafers of roughly 350 m thick using a multi-wire saw. About 50-60

percents of weight of the ingot becomes Si wafers. Fourth process, The Si wafers are doped with dopantsin a diffusion furnace to make p-n junctions after surface etching and then assembled in PV cells by aforming electrode. The last process, the PV cells are strung by solder-coated copper ribbons, laminated byEVA, covered with sheet glass and finally packed into aluminium frames.


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Mono-crystalline silicon ( c-Si) Polycrystalline silicon (p-Si) Amorphous silicon (a-Si)

Figure 3.1-1 Show the c-Si PV, p-Si PV and a-Si PV module production process, respectively.

The polycrystalline silicon (p-Si) PV module (11.6-15.7% efficiency STD)In case of p-Si PV module, new production technologies are expected to be in practical use in the near

future that is solar-grade silicon (SOG-Si) production from raw silica and electromagnetic casting. Acrucible process was adapted for the SOG-Si production, which is continuously cast in ingot withelectromagnetic technology. The ingots are then cut into wafers using multi-wire saw. Several PV cellsare laminated in EVA between a glass sheets and finally aluminium frames are added as present in Figure3.1-1.

The thin film: amorphous silicon (a-Si) PV module (8-12% efficiency STD)Amorphous silicon layers are deposited by plasma-enhanced chemical vapor deposition of the

transparent conducting electrode; the a-Si and the back electrode are carried out on a continuous operating

line. By this technology only cells production process and the after are concerned as show in Figure 3.1-1.

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Enegy requirement (MJ/m2) and CO2 emission (1/100 kgC/m2)

MG-Si Poly-Si Cz-Si SOG-Si

C&cut Cell Prod Modu Ass Other

Figure 3.1-2 Show the energy requirement for 1 m2 of three kinds of PV module.

From Figure 3.1-2, Worst value from three cases of c-Si PV cell production process will be explained.Case A-1, the SiCl4 be neglected, thereforethat all the energy and the materials from MG-Si production topoly-Si production were covered to estimate the energy content of the off-grade Si. In case A-2, the SiCl4

CO2 emission

Energy requirement


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was dealt with as a by-product. In case B the off-grade Si is considered as a waste product fromsemiconductor production, thereforeonly the processes after the primary Cz-Si production were evaluated.

Considering p-Si and a-Si, worst values of three annual cell production scales are considered whichare 10, 30 and 100 megawatts per year.

By the results, the energy requirement for c-Si PV modules production is noticeably higher than p-Siand a-Si PV modules production. This cause from a large amount of heat requires producing of c-Siespecially, Cz-Si production process. Although those for SOG-Si production were approximately half of

the total and more than any other processes, they were much less in comparison with c-Si production.Considering a-Si, the energy requirement is less than the c-Si PV modules and nearly half of those for p-Si PV modules at the same production scale. This cause from only energy require for PV cell and moduleproduction process different from c-Si and p-Si PV module production that use much of energy to preparePV cell.

3.2Energy pay-back time (EPBT) of PV systems and energy content of BOS.

In term of energy, the shorter of EPBT refers to the more useful energy that we can gain from the restof all life time of PV systems after pay off.

The two interesting studies will be described about the energy pay-back time and energy content of

PV systems. These studies indicate that the different of technology and installation can significantly makethe different EPBT for each PV system.

The first study is from the results of the study before of Kasuhiko Kato [5], the EPBT comparisonbetween each type of PV modules production can be described in the figure 3.2-1.

Considering three types of PV cells those are c-Si, p-Si and a-Si, the longest of EPBT is c-Si PVmodule due to the most energy use in production that has already presented. For p-Si and a-Si PVmodules quite similar in EPBT due to the SOG-Si of p-Si that require less of energy.

Considering the less EPBT of the bigger annual cells production scale, by the bigger scale lead to risethe annually energy gain up cause the EPBT become lower.

EPBT (years) and CO2 emission (10g-C/kWh)

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Energy pay-back time (years) and CO2 emission per unit electrical output (10g-C/kWh)

Figure 3.2-1 Represent the energy pay-back time EPBT (years) of a 3-kilowatts peak residential PV powersystem [5].

The second study is from the study of P.Frankl [5], the objective of the study is twofold; the firstgoal is to quantify the relevance of balance-of-system (BOS) in terms of energy consumption andemissions during manufacturing and installation of PV systems. The second objective is to quantify the

CO2 emission

EPBT


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benefits of the integration og PV systems in buildings over there entire life-cycle, in terms of energyconsumption and related emissions. The emissions will be described after this chapter.

As spoken already about the categories of PV system, the PV power plant and sub-category of PVsystems in building will be revealed and compared the value of EPBT.

PV power plant: This installation requires a careful preparation of land and special structures tosupport the PV panels. An electric efficiency about 85 percents has been assume for these systems.

Flat roof PV: PV modules are fixed on the flat surface of the rooftop by means of suitable light

structure. Exposure is optimized.Tilted roof PV: There are two kind of tilted roof, retro-fit that is directly applied to the existing

surface of the roof and integrated that PV system and building are designed together.Facade PV: Again there are 2 kinds of faade that are retro-fit and integrated faade.

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Figure 3.2-2 Primary energy content of the BOS of present PV systems.

For PV systems, balances of systems (BOS) are considered in term of energy content that aredifferent for each category of PV systems as show in figure 3.2-2. The energy requirement and energycontent of BOS both are necessary for considering which system could be significantly interesting in termof energy. The optimization of BOS in the future can lead to reduce the energy consumption and alsodecrease the EPBT of PV systems for example using a large fraction of recycled, secondary material. Forexample, Table 3.2-1, show that the secondary aluminium has energy content particularly less than

primary aluminium.

Table 3.2-1 Total energy content and specific CO2 emissions of BOS material (total values adapted from Refs 31)

Parameters Materials SteelPrimary

aluminium

Secondary

aluminium

Light

concreteConcrete Copper Glass PVC Clay

Total primary energy content

of materials (MJth/kg)32 198 12.6 4.4 1.63 70 14.4 66.8 10.7

Converted Electricity (MJth/kg) 20.25 156.51 0 0.92 0.37 43.45 1.1 39.22 0.46

CO2 emission (kgCO2/kg) 1.91 10.59 0.51 0.28 0.16 3.09 0.77 4.2 0.66


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EPBT (years)

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Figure 3.2-2 Illustrate the energy pay-back time of present mono-crystalline silicon PV systems (mean annual

insolation 1700 kWh m

-2

year on a 30 tilted south-oriented surface, cell efficiency 14.5%)

The EPBT of the PV systems that show in Figure 3.2-2 is quite high, even if the systems are installedin places with a relatively high sun radiation. The main reason is the low efficiency of crystalline siliconfeedstock and wafer production process which are not optimized for PV cell production.

The most effective PV systems are the simple installation on flat roofs that can adjustable thedirection received sun light for optimized energy yield. Faade show even worse results because of thebad exposure to the sun at these latitudes.

Conclusion from two studies above, if interest only in energy term the optimized case are the PVsystems in building base on amorphous silicon technology especially, the flat roofs PV systems. Theenergy pay back time now three to nine years and will decrease to one to two years. There is a matter of

debate for PV systems that have storage components with lead-acid battery such as standalone PV system,solar home system, and etc. The energy pay back time is now 7 to 10 years cause from life time of battery(lead-acid) is five years or less [1]. However, these results are not enough to compare and evaluate thebenefit with the other kind of PV system such as stand alone PV systems or hybrid PV systems or theother type of energy technology. Thereforethe environmental term and economic term should be lead toconsider for comparison and evaluation the benefit next.

3.3Life-cycle CO2 emission and some significant gasses (GHG) emission.

From the study of Kasuhiko and P.Framkl [5], the results of CO2 emission are quite similar to the

energy term that show the optimized case is the PV systems base on amorphous silicon technology. Formono-crystalline silicon the high CO2 emission come from the Cz-Si and wafer production process. Theworst case of PV systems is not faade PV but is from PV power plant (of polycrystalline silicon) becausefrom the high primary energy content of BOS of PV power plant that leads to produce more CO2emission.

The study of M.E.Watt [5], three options of household at the same level of annual energy demand arecompared the CO2, SO2 and NOx emission that are represented in the figure 3.3-1.

The first option is PV stand alone or off-grid power supply system with 2 kWp polycrystallinesilicon PV array, 36 kWh of lead acid battery storage (85% efficiency and 50% maximum depth ofdischarge), 3 kW inverter (90% efficiency) and 5 kVA diesel generator.

The second option is grid-connected PV system with 2 kWp polycrystalline silicon PV array, 3 kWinverter (95% average efficiency) and 10 kVA pole top transformer. Network losses average 12% andcentral grid generation is modeled on the Australian average, which is largely coal based with minor useof hydro and natural gas.

Heat recoveryIntegratedRetrofit


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The third option is grid connection that the same grid extension is used as for option 2, with no PVrelated components.

Emission per year

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Figure 3.3-1 Represent life-cycle CO2, SO2, NOx emission for the different energy supply/demand options (onlyconcerned information is presented adapted from Refs 32).

In case of CO2 emission, the high emission come from both grid connection and off-grid PV supplyoption because the use of fossil fuel-based electricity generation.

In case of NOx emission, the highest obviously come from the off-grid PV supply option due to theuse of the back-up diesel generator.

In case of SO2 emission, the highest come from the grid connection due to the high coal component ofthe Australian central grid generation mix. The lowest emission come from off-grid PV supply option but

in case of low electricity use that only PV supply in grid-connected PV system, the lowest emission comefrom grid-connected PV system due to the batteries in off-grid PV supply cause the higher SO2 emission.

Even more, the figure 3.3-2 show specific CO2 emission of different kind of electrical power plants,the different type of PV cell emit the different level of CO2 because the different of technologyproduction [6].

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Figure 3.3-2 Comparison specific CO2 emission of differentkind of electrical power plants (adapted from Refs 22)

Although PV power system emissionobviously less than fossil fuel-based powerplant but comparison with wind and hydropower plant, PV power system quite higheremit CO2 due to the energy using during

manufacturing that already presented in thetopic before.

In the other word, if consider only CO2emission term, PV power systems are not thebest choice when compare with the otherrenewable energy technology but vastly betterthan fossil fuel-based power system.

-------------------------------------------------From figure 3.3-2

a - At 5.5 m/s

b - For conditions in central Europe

c - Produced in Europe, irradiance:1700

kWh/m2-a


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4. PROBLEMS AND BARRIERS OF RESEARCH AND DEVELOPMENT OF PV TECHNOLOGY.

Although the PV systems are no emission when operating and comfortable use for general but thiskind of technology still has main problems that cause unaccepted for worldwide.

These problems are the low efficiency of PV modules as show in figure 4.1-1 [2] and the very highcost of PV systems compare with conventional energy systems at present as show in figure 4.1-2 [1].

4.1 Efficiency of PV technology

Solar cell material Cell efficiency

(laboratory)

Cell efficiency

(production)

Module effiency

(series production)

Mono-crystalline silicon 24.7% 18.0% 14.0%

Polycrystalline silicon 19.8% 16.0% 13.0%

Ribbon silicon 19.7% 14.0% 13.0%

Crystalline thin-film silicon 19.2% 9.5% 7.9%

Amorphous silicona

13.0% 10.5% 7.5%

Micromophous silicona

12.0% 10.7% 9.1%

Hybrid HIT solar cell 20.1% 17.3% 15.2%

CIS, CIGS 18.8% 14.0% 10.0%

Cadmium telluride 16.4% 10.0% 9.0%

III-V semiconductor 35.8%b

27.4% 27.0%

Dye-sensitized cell 12.0% 7.0% 5%b

a In stabilized state

b measured with concentrated irradience

c small production runs

Figure 4.1-1 Show maximum efficiency in photovoltaic.

In case of mono-crystalline silicon that has the highest commercially module efficiency. The hybrid

HIT solar cell still unaccepted in commercial and III-V semiconductor though achieve the highestefficiency but they are not competitive in price.

The main cause of low efficiency of PV module is the restriction of material that cannot convert all ofsolar energy into electricity due to the losses of solar energy in PV cell and mismatching between bandgap of material and the spectrum of the light incident [3]. Although the best material has found now suchas gallium arsenide (GaAs), but can reach efficiency only 27% for PV module with very high cost [2].

4.2 Cost of PV systems.

In order to consider cost of PV system, the figure 4.2-1 show significant barrier that can cause the PVtechnology still tiny accept for worldwide.

Due to main cost of PV system come from cost of PV module [2], thereforethe research and the

development have direction to rise efficiency up and reduce the cost of PV system for example theamorphous silicon technology that quite low cost production or the hybrid HIT solar cell that rise theefficiency up on based of crystalline and amorphous silicon technology.

For integrated PV systems in building, especially in countries where additional subsidies areavailable, this can lead for saving in construction materials for the roof and faade.

From the study of M.E.Watt [5] above, a 2-km single phase extension is priced at around $21,200,with electricity priced around $0.12/ kWh. It should be noted that a higher grid extension cost, resultingfrom tree clearing, difficult terrain or a greater distance, would make the demand management optionseven more cost effective. When a PV system is added to grid, the capital cost increase to $41,860. Theoff-grid option has the highest capital cost and annual average costs but show significant reductions withreduced electricity demand.


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Current and potential future electricity cost (/kWh)

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Figure 4.2-1 Illustrate the current and potential future energy cost of renewable energy technology (2003) [1].

Grid-supplied electricity in urban areas: off-peak 2-3 /kWh and peak 15-25 /kWh.

From the IEA-PVPS reported [4], in 2003 system prices in the off-grid sector up to 1 kW varied fromabout 8 USD to 25 USD per watt. The large range of reported prices is a function of country and projectspecific factors. A system price of about 10 USD to 12 USD per watt appears to be common. Off-gridsystems greater than 1 kW tend to show similar variation and prices.

The installed price of grid-connected systems in 2003 also varied, both within and between countries.The lowest reported prices were close to 4 USD per watt and are unlikely to be a true reflection of costs;prices of 5 USD to 7 USD per watt are more typical prices.

System prices for off-grid applications in each country tend to be higher by about a factor of two thanthose for grid-connected applications as the latter do not require storage batteries and associatedequipment. Some unique building integrated projects provide an exception to this situation.

Considering the grid-connected PV systems, one more important factor of efficiency is indicated bythe parameter called PR - Performance Ratio that is used to indicate the overall effect of losses on thearrays rated output as show in Table4.1-1. From the analysis of grid-connected PV systems in the IEA-PVPS database, it was learnt that the average annual yield (Yf) only slightly fluctuates from one year toanother.

From annual performance ratios (PR) calculated from

387 annual datasets of 170 grid-connected PV systems.The annual performance ratio (PR) significantly differsfrom plant to plant and ranges between 0.25 and 0.9 withan average PR value of 0.66 for 170 PV systems. It wasfound that well maintained PV systems operating wellshow an average PR value of typically 0.72[7].

From 27 domestic standalone and standalonehybrid systems. Annual performance ratios range from0.2 to 0.6 for off-grid domestic applications dependingwhether they have a back-up system and from 0.05 to0.25 for off-grid professional systems, which are oftenoversized for reliability reasons. The analysis of stand-

alone systems in terms of performance ratio shows thatthe PR does not reflect the proper technical operation ofa system as is the case for grid-connected systems [7].

Table 4.1-1Estimated losses of energy flow from agrid-connected PV system. [2]

Loss Factors of PV system % losses

1.Module efficiency deviation 4.50

2.Module soiling 2.50

3.Module Temperature 3.50

4.Shading 2.00

5.Mismatching and DC losses 3.50

6.MPP mismatch error 1.50

7.Inverter losses 7.50

8.AC losses, meter 3.00

% losses total ( PR = 72 %) 28.00


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Each type of grid-connected PV systems in buildings such as PV flat rooftop, tilted roof PV orfaade PV system, these can make the differ PR depend on the exposure to sun light and can cause thedifferent level of energy pay-back time EPBT as already presented.

Furthermore the grid-connected PV systems in buildings have to consider the quality of poweryield and the term of safety when connect to the grid. For example:

Islanding effect is a major problem for grid-connected systems. This can be defined as the operatingcondition where a distributed generation maintains the electric supply on a local section of distribution

system, which is disconnected from utility source following an opening of a circuit breaker on adistribution line [8]. Islanding may cause problems such as human safety and equipment maintenance if itcontinues for a long time. It is important to clarify the condition under which continued islanding occurs,and verify the necessity of measures for prevent islanding and effectiveness of these countermeasures,especially when a large number of PV systems are interconnected to one distribution line [9].

Poor power factor condition: Many case studies found that at the low level of solar radiation, thepower factor seems to be far from unity [10].

If there is power from many PV systems at low power factor generated to distribution line, thehigher loss both from distribution line and generator will happen. Typically the allowable of power factoris 0.85 or higher. Thereforethe owner of PV systems have to improve power factor before connect to gridthat means the addition of operating cost. Another way to avoid this cost may be not to connect PVsystem when the low power factor occurs. However, the annual energy yield will decrease cause from this

technique.Harmonics distortion: Two case studies show that the less solar radiation, the THDC total harmonic

distortion current will exponentially rise. As the number of grid interconnected increase when eachharmonic from each PV system superimposes on one another or may decrease when harmonics cancel outone another. From the results, the third and fifth harmonic currents from inverter have almost the samephase displacement and the total harmonic current could be superimposed [9], while higher harmonicsfrom inverters have different phase displacement even if the same control scheme is employed and totalharmonic current could be cancelled. The increasing of the third and fifth harmonic with the number ofconnected cause from the excitation current of the isolation transformers [9].

Although, the power quality and safety problems are quite less than module efficiency barriers butthese can cause the higher cost of system due to the more investment in protector or method to improve

quality and safety.

5. PROGRESS AND TREND OF PV SYSTEMS IN BUILDING.

From the aim of the Kyoto Protocol is to reduce CO2 emissions. Even for countries choosing not toratify the agreement there is still a commitment to reducing their emissions as well as encouraging thedevelopment of renewable energy technology. In order to attain these climate protection aims, two routesmust be taken in parallel which should be given equal importance:

- The use of renewable energies must be expanded.- All energy-saving potentials must be exhausted.

In general, nearly every country has an enormous potential for using renewable energies as present infigure 5-1. Although PV technology today provides far less than 1% of the electricity supply, but it haslarge potential. Assume a 25% per year growth rate for world PV shipment (as projected by the NationalCentre for Photovoltaics in the US), cumulative growth of world PV shipment as shown in Figure 5-2 canbe expected.

Today, the applications where PV systems are economically competitive especially, grid-connectedPV as show in figure 5-3, in comparison with conventional power systems are generally smallapplications or at locations remote from the mains grid. However, in some countries such as Spain,German, Italy, Japan and some states in the US where high feed in tariffs or grants are offered, grid-connected PV systems can be economically feasible.

The extent to which grid-connected PV systems in general will come to form a significant proportion

of power supply depends on the future reduction of costs.


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1800.0

2000.0

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

CumulativeinstalledPV

power(MW)

CAN AUT MEX CHE FRA ITA ESP AUS NLD USA DEU JPN

Figure 5-1 show the Total installed capacity in the selected countries and Annual sales and key targets (MW) [4].

0

10

20

30

40

50

60

70

80

90

100

20 00 2 00 2 20 04 20 06 20 08 20 10 2 012 2 014 2 01 6 2 01 8 2 020

Year

GigaWatts(peak)

Figure 5-2 Show expected cumulative growth of world PVshipment [2].

Like the vast majority of PV generation capacity installed in the IEA PVPS countries, most PV

installed in other parts of the world at present is being driven from the top-down (i.e. subsidized), throughnational targets and/or bilateral or multilateral development programs. Key applications for solar PVoutside the IEA PVPS countries are small solar home systems, SHS, for households (typically 20 W -100 W), village power stations (typically 500 W - 2 500 W), and power for health centers, schools, waterpumping and telecommunications systems. An important distinction is that for the remote or rural areas ofdeveloping countries which account for much of the market in non IEA PVPS countries, PV is often acost effective solution to energy service provision.

Figure 5-3 Show the worldwide turnover of PVtechnology according to application areas, 2001.

PV/diesel10%

Grid-connected42%

Solar power station>100 kW 2%

Consumergoods 14%

Off-gridindustrialcountries 6%

Off-griddevelopingcountries 12%

Communication14%


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6. CONCLUSION

All of factors or parameters concerned for assessment PV systems in buildings have roughly dividedinto 3 levels of results. The simplified comparison between PV system technologies and betweenrenewable energies will be illustrated in Table 6-1.

Table 6-1 Represent the conclusion divided into 3 levels comparison the results of the studies and reports.

No. Parameters High Medium Low

1 Energy requirement mono-crystalline silicon polycrystalline silicon amorphous silicon

2 EPBT and CO2 emission mono-crystalline silicon polycrystalline silicon amorphous silicon

3 EPBT PV grid-connected Faade PV plant, flat roof, tilted roof PV system with heat recovery

4 CO2 emission PV

systems

Grid system Off-grid PV grid-connected PV

5 SO2 emission PV

systems

Grid system grid-connected PV Off-grid PV

6 NOx emission PV

systems

Off-grid PV Grid system grid-connected PV

7 CO2 emission Power

plant

Lignite,coal,oil natural gas PV power,Wind power

8 Module Efficiency Hybrid HIT c-Si,p-Si, ribbon thin-film silicon, a-Si, CIS,

CIGS, Cadmium telluride

9 Market share of PV cell p-Si , c-Si ribbon, a-Si CIS, Cadmium telluride

10 Electricity cost RE PV Bio-ethanol, solar thermal,

marine

wind, hydro, bio-teat,

geothermal

11 Cost of PV system Off-grid PV Grid-connected PV

12 Performance Ratio Grid-connected PV Off-grid PV

13 Installed Capacity Japan,German,US Natherland,Australia, Spain,

Italy, France, Switzerland

Mexigo, Austria, Canada,

Norway, Korea

14 Worldwide turnover of PV Grid-connected PV communication, customer

goods, off-grid

PV power station

15 Percent increasing

installed

Wind, PV Low-temp solar heat,

Geothermal, Solar thermal

Biomass, Hydro, Marine

Although the PV systems in buildings cannot competitive with conventional energy at present causefrom the higher cost of systems and the low efficiency, the trend show that the high growth of PV

technology cause the reducing of cost and encouraging the development of technology that can lead tocompetitively compare with others energy technology in the near future.However, by the large amount of PV systems in the future can cause some problems influence the

environment, thereforethe environmental impacts have to be noticeably considered further.


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7. REFERENCE

[1] World Energy Assessment, Energy and the challenge of sustainability , United Nations DevelopmentProgramme , 2000.

[2] The German Solar Energy Society,2005, Planing and Installing Photovoltaic System, James & James(Sciences publishers).

[3] Godfrey Boyle, Renewable Energy, The Open University, 1994.

[4] IEA-PVPS, TRENDS IN PHOTOVOLTAIC APPLICATIONS Survey report of selected IEA countriesbetween 1992 and 2003, Report IEA-PVPS T1-13,2004. Available from http://www.oja-services.nl/iea-pvps/products/download.htm, [accessed 1 July 2005].

[5] Martin A. Green, Eduardo Lorenzo, Harold N. Post, Hans W. Schock, Ken Zweible and Paul A. Lynn, 1998,Progress in PHOTOVOLTAICS Research and Applications, Volume 6 Number 2, July-August 1998.

[6] S. Krauter, R. Ruther, 2003, Considerations for the calculation of greenhouse gas reduction byphotovoltaic solar energy, Laborato rio Fotovoltaico, UFRJ-COPPE/EE, Caixa Postal 68504 Rio de Janeiro,

21945-970 RJ, Brazil, Lab Solar, UFSC-EMC, Available from www.sciencedirect.com , [ accessed 1 July2005].

[7] IEA-PVPS Task 5, 2002, Grid interconnection of Building integrated and other dispersed phovoltaic powersystems, Available from http://www.oja-services.nl/iea-pvps/products/download.htm , [accessed 28 August2002]., [accessed 28 August 2002].

[8] Arindam Ghosh,Gerard Ledwich ,2002, Power Quality Enhancement Using Custom Power Devices,KLUWER Academic Publishers ,2002.

[9] IEA-PVPS T5-02 ,1999. Demonstration test results for grid interconnected photovoltaic power systems,Available from http://www.oja-services.nl/iea-pvps/products/download.htm, [accessed 28 August 2002].

[10] Chenvidhya Dhirayut,2002, PV Grid-Connected Systems for Residential distribution System : DYNAMICIMPEDANCE CHARACTERIZATION OF SOLAR CELLS AND PV MODULES , School of Energy andMaterial, KMUTT, 2002.

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Renewable Energy Applications Grid-Connected PV System in Building