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 II. III. MAIN COMPONENTS Solar Panel Solar Charge Controller Grid Connected Inverter Grid Interactive Inverter Battery BLOCK DIAGRAM REPRESENTATION OF 100KW SOLAR POWER PLANT 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 (standalone). 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 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 694
International Journal of Emerging Technology and Advanced Engineering 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. Total no: of modules = 432 For 30kW solar module: DESIGN ANALYSIS Open Circuit Voltage rating of 30kW inverter = 550V Panel voltage (V oc ) = 37.5V No: of panels connected in series = Panel working voltage = 30.5V = 13 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 I sc = 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 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. Panel Working Voltage = 30.6V Series Panel Working Voltage = 7 30.6 = 214.2V 695
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 4 th 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) 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) Period TABLE I The Savings Due To Installation of Solar Plant (24 Hrs-Use) 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 Figure 3: Energy Charges During Normal Time 696
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 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 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 5.5 697
2.2 Diesel Savings TABLE II Fuel Consumed By The Generator Before Installation of Solar Panel DATE QUANTI TY(Ltr.) UNIT PRICE(Rs) 29-03 -2012 200 44.55 26-06 2012 200 44.55 11-10-2012 200 49.60 06-11 2012 200 49.78 17-11-2012 200 49.78 19-12-2012 200 49.78 19-01- 2013 200 50.30 11-02- 2013 200 50.30 19-02- 2013 200 50.86 05-03- 2013 200 50.86 09-04- 2013 200 51.37 12-04- 2013 200 51.37 23-04- 2013 200 51.41 TOTAL 2600 AMOUNT (Rs) 8910.00 8910.00 9920.00 9956.00 9956.00 9956.00 10,060.00 10.060.00 10,172.00 10,172.00 10,274.00 10,274.00 10,282.00 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. 698
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. 699