Solar Off Grid BFD

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

694

Performance Assessment of 100 kW Solar Power Plant Installed

at Mar Baselios College of Engineering and Technology Prakash Thomas Francis, Aida Anna Oommen, Abhijith A.A, Ruby Rajan and Varun S. Muraleedharan

Dept. of Electrical and Electronics Engineering, Mar Baselios College of Engineering and Technology, Nalanchira,

Thiruvananthapuram-695015

Abstract - The objective of this project work is to analyze

the performance of a 230Wp capacity solar panel installed in

Mar Baselios College of Engineering and Technology. The

total capacity of the plant is 100kW. The first phase of the

project includes the comparison of the current electricity bill

with the bill before installation the photovoltaic system and

conducting detailed analysis to understand (1) Energy

consumption (kWh) normal vs. time, (2) Energy consumption

peak vs. time .The second phase includes the comparison of

the fuel consumption by the generator before and after

installation of the solar panel. The third phase includes the

study of the direct and indirect advantages of installing a solar

panel in this institution for e.g. bill savings, tax savings and

power being supplied back to the grid.

Keywords-- Charge Controller, Grid Connected Inverter,

Grid Tied Inverter, Net Metering, Solar Plant, Off-grid

I. INTRODUCTION

Solar energy is a readily available non-conventional type

of energy. The energy from sun is in the form of radiation.

The intensity of solar radiation reaching earth’s surface is

around 1369 watts per square meter. A solar electric system

is typically consists of solar panels, inverter, battery, charge

controller, wirings and support structures. The three most

common types of solar electric systems are grid-connected,

grid-connected with battery backup, and off-grid (stand-

alone). Sunlight is always varying and this varying form of

sun’s energy is used to power the solar panels using the

photovoltaic (PV) effect. PV effect causes electrical

current to flow through a solar cell when exposed to

sunlight. Several solar panels combined together make a

solar array. There are four types of panels depending upon

their material composition and design. They are:

1. Monocrystalline silicon

2. Polycrystalline-silicon

3. Thin film

4. Multi-junction

II. MAIN COMPONENTS

Solar Panel

Solar Charge Controller

Grid Connected Inverter

Grid Interactive Inverter

Battery

III. BLOCK DIAGRAM REPRESENTATION OF 100KW

SOLAR POWER PLANT

Figure 1: Block Diagram of 100KW Solar Power Plant

A 99.36kWp solar electric system is installed in

our college.

It is a grid interactive system with battery backup.

The solar power plant uses imported Leonics

make 100kW grid interactive inverter supported

by additional 3 numbers of 30kW grid connected

inverters.

Two numbers of 30kW inverters and a total

capacity of 59.8kWp solar module is installed on

the B block. A 30kW grid connected inverter and

29.9kWp solar module is installed on the A block.

Most important aspect of the installation is

informative energy monitoring and display



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system, which can be monitored by 24×7 on

website.

A 9.66kWp solar module on the mechanical block

and control panel load is connected across the

100kW grid interactive inverter.

The 100kW grid interactive inverter will work in

charger mode or inverter mode depending on the

battery voltage at that time. In case of deep

discharge or unavailability of sunshine, the battery

will be charged by the utility grid.

During day time if the solar module energy is less

compared to energy required by load then excess

energy required by the load will be taken by the

utility grid.

When excess energy is generated after meeting

our load demands it is then fed back to the grid.

IV. DESIGN ANALYSIS

Total no: of modules = 432

For 30kW solar module:

Open Circuit Voltage rating of 30kW inverter = 550V

Panel voltage (Voc) = 37.5V

No: of panels connected in series =

= 13

Panel working voltage = 30.5V

Series Panel Working Voltage = 13×30.6 = 397.8V

Total power = (V×I) = 30kW

Total power = (V×I) = 30kW -------- (1)

From equation (1)

Working current

= 75.414A

From the panel details we get Isc = 8.18A

No: of panels connected in parallel

= 10

For 10 kW solar module:

Voltage rating = 240V

No: of panels connected in series =

(Inverter Voltage)/(Panel voltage)

= 7.8 ≈ 7

Panel Working Voltage = 30.6V

Series Panel Working Voltage = 7×30.6 = 214.2V

Total Power = (V×I) = 10kW

Working Current

= 46.68

No of panels connected in parallel

= 5.70 ≈ 6

Therefore, for 30kW inverter, we connect the panels as

13×10(i.e. 13 panels are connected in series and 10 in

parallel respectively) and for battery charging purpose, we

connect the panels as 7 × 6 (i.e. 7 panels are connected in

series and 6 in parallel respectively).

Battery Design

Load connected - 90kW

Backup in hours - 1hr

No. of units consumed = 90×1=90kWh=90units

Inverter Working Voltage = 240 V

Total Ah = 90000/240 = 375Ah

Battery rating (50% depth of discharge) = 375×2=

750 ≈ 600 Ah battery used here.

C-10 battery rating is used

V. VARIOUS ANALYSES PERFORMED

The analyses consist of two parts:

1. Bill Analysis

2. Economic Analysis

To analyze the performance of the solar power plant

installed in the college, the electricity bills of our college

before and after installation of the solar plant were

analyzed and graphs were plotted The electricity bills are

classified into three zones. The first zone is the normal time

which is from 6 a.m. to 6 p.m. the second zone is the peak

time which is from 6 p.m. to 10 p.m. and the third zone is

the off peak time which is from 10 p.m. to 6 a.m. As sun

shines only during day time the graphs for normal time is

only needed to be considered for assessment.



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1. Bill Analysis

1.1 Demand in kWh for Normal Time

Figure 2: Energy Consumption in kWh for Normal Time

Before installation of solar plant

It was found that during the years 2011-2012 from

January-April the demands were almost same. There was a

peak during March 2011 and 2012 due to construction

works in college and also due to the high temperatures

during summer. During April 2011 and 2012 the demand

decreased as the college was closed for study leave. Energy

consumption increased during the year 2012 compared to

2011 due to the admission of more number of students to

the college for the new academic year. During June-July

2012 there was an increase in demand due to hostel

construction. During September 2012 there was a peak due

to welding works in 4th

floor B-block. From January –

March 2013 as no construction works were there, the

energy consumption was also low.

After installation of solar plant

It was found that the energy consumption was stabilized.

The demand from KSEB was reduced considerably.

1.2 Energy Charges (Normal Time)

Figure 3: Energy Charges During Normal Time

Considering the years 2011-2012-2013 the tariff rate

increased yearly. From Jan 2011 to June 2012 the tariff

rates for the demand charges were Rs.175 for normal time,

Rs.87.5 for peak time and Rs.93.33 during off peak time.

From July 2012 to April 2013 the tariff rates for demand

charges were Rs.200 for normal time, Rs 100 for peak

times and Rs.106.667 for off peak time. Then from May

2013 onwards the tariff rates for demand charges were

considered to be equal to Rs.400 for a whole day.

When the energy charges bills were considered it was

found that during the year 2011 as the tariff rate was low

the energy charges were also less compared to 2012 when

the tariff rates increased as well as construction works

going on. But even though the tariff rates increased

considerably during the year 2013 it is clearly seen that the

energy charges were reduced considerably after the

installation of the solar plant.

1.3 The Savings Due To Installation of Solar Plant-(24 Hrs

Use)

TABLE I

The Savings Due To Installation of Solar Plant (24 Hrs-Use)

Period PV

Energy

(kWh)

Energy

drawn

from

KSEB

(kWh)

Total

energy

consumed

(kWh)

Energy

charges

paid to

KSEB

(Rs.)

Amount

payable to

KSEB if PV

is absent

(Rs.)

Net

Savings

to

College

(Rs.)

July

9346.7

13632

22978.7

83497.5

139577.7

56080.2

Aug

12481.5

14193

26674.5

86368.5

161257.5

74889.0

Sep

12511.2

13149

25660.2

79762.5

154829.7

75067.2

Nov

11620.7

13101

24721.7

79587.0

149311.2

69724.2

Dec

13591.4

12042

25633.4

73453.5

155001.9

81548.4

Jan

13408.9

15858

29266.9

96565.5

177018.9

80453.4



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For the evaluation purpose, a period from July 2013 to

December 2013 was considered. The energy consumed

from KSEB with and without the solar plant was

considered. The energy consumed from KSEB with solar

plant installed was obtained from the electricity bill. The

energy from solar was obtained from the server. Therefore

the energy consumed from KSEB if the solar plant was not

installed was calculated by adding the above two energy

consumption. The energy charges paid to KSEB with and

without the installation were also calculated and the

savings were calculated.

2. Economic Analysis

If money invested is in a bank

Total initial investment = Rs 2, 67, 00,000.00

Subsidy = 30% of initial investment = Rs1,87,00,000.00

If rate of interest chosen to be 9.17%

Then yearly interest = Rs17, 14,790.00

Since interest exceeds Rs 15, 00,000.00, then tax is

deducted at source 30% of yearly interest i.e. = Rs

5, 14,437.00

So yearly we get Rs (17,14,790 - 5,14,437) = Rs

12,00,353.00

So monthly interest after deducting tax = Rs 1, 00,029.41

Assuming factors to be remaining constant we will get

the initial investment within 15-16 years, if money is

invested in the 100 kW solar power generation project.

2.1 Indirect Saving

Calculation on tariff

Taking bills of November 2012 & 2013 to show the

invisible or indirect savings from electricity bills.

Tariff rates of November 2012 are kept constant, the

number of units consumed in august are taken and

following calculations are done.

Tariff rates for the month of august 2012 are

Demand charge (normal) – Rs 200

Demand charge (peak) - Rs 100

Demand charge (off peak) – Rs 106.67

Energy charge (normal) - Rs 5.5

Energy charge (peak) - Rs 7.7

Energy charge (off peak) - Rs 4.65

Total electricity bill involves the sum of=total demand

charge + total energy charge + PF incentive/penalty +

electricity duty and electricity surcharge.

Then keeping the tariff rates of November 2012 constant

and multiplying the units consumed in November 2013 we

get the bill as

=113×200+45×100+0+7515×5.5+2469×7.7+4215×4.65+8

349.75+340.80

Bill in November 2013 using previous year tariff rates=Rs

93,919.50.

Bill in November 2012= Rs 2, 08,394.00

Thus bill saved = Rs 1, 14,570.50

Inference: Thus if we take the bills from June 2013-

november2013 we indirectly get a average saving of Rs

1,14,570.50 month so this accumulates to a total saving of

=1,14,570.50 × 12= Rs 13,74,000.00



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2.2 Diesel Savings

TABLE II

Fuel Consumed By The Generator Before Installation of Solar Panel

DATE QUANTI

TY(Ltr.)

UNIT PRICE(Rs) AMOUNT

(Rs)

29- 03 -2012

200

44.55

8910.00

26-06 2012

200

44.55

8910.00

11-10-2012

200

49.60

9920.00

06-11 2012

200

49.78

9956.00

17-11-2012

200

49.78

9956.00

19 -12-2012

200

49.78

9956.00

19-01- 2013

200

50.30

10,060.00

11-02- 2013

200

50.30

10.060.00

19-02- 2013

200

50.86

10,172.00

05-03- 2013

200

50.86

10,172.00

09-04- 2013

200

51.37

10,274.00

12-04- 2013

200

51.37

10,274.00

23-04- 2013

200

51.41

10,282.00

TOTAL

2600

1,28,902.00

TABLE III

Fuel Consumed By the Generator after Installation of Solar Panel

DATE QUANTITY(Ltr.) UNIT

PRICE(Rs)

AMOUNT

(Rs)

30-04-2013 200 51.41 10,282.00

14-05-2013 200 52.50 10,500.00

13-06-2013 200 53.10 10,620.00

06-11-2013 200 57.02 11,404.00

17-12-2013 200 57.63 11,526.00

20-02-2013 200 59.32 11,864.00

TOTAL 1200 66,196.00

Average diesel consumption before installation of solar

plant=2600/12= 216.6 liters

Average Diesel consumption after installation of solar

plant=1200/12= 100 liters

Therefore savings in diesel consumption = 216.6 -100=

116.6 liters

In 2012 we consumed about 2600 litres of diesel for

providing fuel to the generator

And from the table we can see the overall money we

paid for diesel alone was = Rs 1,28,902.00

In 2013 we only consumed about 1200 litres of diesel

and the total cost came to = Rs 66,196.00

Based on this we saved about Rs 63,000.00 per annum

2.3 Tax Savings

We almost get a tax saving of=30% of (13,74,

000+63000)=Rs 4,31,100.00

So on conclusion we can see that on adding tax savings,

indirect savings and generator fuel consumption savings we

get almost a total savings of

Tax savings = Rs 4, 31,100.00

Indirect savings = Rs 13, 74,000.00

Saving on diesel consumption = Rs 63, 000.00

So overall we have a saving of Rs 18, 68,100.00

So if we invest the money in a solar project we would get

the initial investment within a period of 9-10 years.



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VI. CONCLUSION

The installation of 100kW solar power generation plant

at Mar Baselios College of Engineering and Technology

not only provides a self-sustaining way of producing power

from renewable energy source (i.e. sun) but also provides

economic benefits. From the bill assessment it was found

that the energy demand as well as the energy charges

decreased after the installation of solar panel. From the

economic assessment it was found that a considerable

amount of savings were made and the payback period was

found to be about 9-10 years.

If net metering is also taken into consideration this system

will become more economically viable. Net metering

enables the user to sell the excess energy back to the utility

grid. Thus the installation of such a renewable power

generation plant not only helps in achieving economic

benefits but also reduces impact on the environment by

reducing pollution, and implications due to climate change.

VII. ACKNOWLEDGEMENTS

We thank Prof. M.K. Giridharan (Head of Department,

Dept. of EEE) for his visionary leadership, without

which the project would not have been possible. Our

sincere gratitude to Ms. Archana A. N (Asst. Prof., Dept. of

EEE) for helping the team with research analysis.

REFERENCES

[1] PradhanArjyadhara, Ali S.M, Jena Chitralekha ,

“Analysis of Solar PV cell Performance with Changing

Irradiance and Temperature”, International Journal Of

Engineering And Computer Science ISSN:2319-7242,

Volume 2 Issue 1 Jan 2013 Page No. 214-220.

[2] Hanif M., M. Ramzan, M. Rahman, M. Khan, M. Amin,

and M. Aamir, “Studying Power Output of PV Solar

Panels at Different Temperatures and Tilt Angles”,

ISESCO JOURNAL of Science and Technology, Vo l u m

e 8 - N u m b e r 1 4 - N o v e m b e r 2 0 1 2 ( 9 - 1 2 ).

[3] E M Natsheh and A Albarbar, “Solar power plant

performance evaluation: simulation and experimental

validation”, 25th International Congress on Condition

Monitoring and Diagnostic Engineering, Journal of Physics

: Conference Series 364 (2012) P(1-13)

[4] Yousif I. Al-Mashhadany, Mouhanad F. Al-Thalej,

“Design and Analysis of High Performance Home Solar

Energy System”, Anbar Journal for Engineering Sciences,

2011.

Documents

Solar Off Grid BFD