Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 5, No. 1, 14-20 2021 DOI: 10.33805/2576-8484.189 © 2021 by the authors © 2021 by the authors History: Received: 6 January 201; Accepted: 6 March 2021; Published: 12 March 2021 * Correspondence: jakawindarta@lecturer.undip.ac.id Technical and Economical Feasibility Analysis on Household-Scale Rooftop Solar Power Plant Design with On-Grid System in Semarang City Jaka Windarta1,3*, Singgih Saptadi2, Denis3, Dimas Adi Satrio3, Johanes Soritua Silaen3 1Magister of Energy, School of Postgraduate Studies, Diponegoro University, Semarang, Indonesia; jakawindarta@lecturer.undip.ac.id (J.W.). 2Department of Industrial Engineering, Faculty of Engineering, Diponegoro University, Semarang, Indonesia 3Department of Electrical Engineering, Faculty of Engineering, Diponegoro University, Semarang, Indonesia Abstract: Utilizing rooftops as a solar power plant system on the grid can be an effective and efficient solution to reduce electricity bills. This research aims to design and analyze the potential of 1215 Wp solar power plant rooftop with on grid system household scale in terms of techno economy. Using each of the two alternatives to the main components of solar panels and inverters, there were 4 variations of the component configuration design in this study. Variation 1 uses Canadian solar panels with solax inverters. Variation 2 uses Canadian solar panels with so far inverters. Variation 3 uses risen solar panels with solax inverters. Variation 4 uses risen solar panels with sofar inverter. Through PVSyst 6.43 software, with an average radiation average of 5.48 kWh/m2/day, the potential energy production of each variation of 1215 Wp rooftop solar power plant household scale are 1873 kWh, 1893 kWh, 1865 kWh and 1885 kWh. The investment cost of 1215 Wp rooftop solar power plant ranges from IDR25,220,000-IDR27,020,000 with Net Present Value ranges from IDR15,309,805- IDR17,421,839, Benefit Cost Ratio ranges from 1,489-1,588, Payback period ranges from 10.38 – 11.02 years and Internal Rate of Return value ranges from 8.8-9.56%. Keywords: Benefit cost ratio, Internal rate of return, Net present value, Payback period, PVSyst 6.43, Solar Power Plant. 1. Introduction The demand for electricity has always grown from time to time compared to other energies. The electricity demand in Indonesia is projected to meet 2.214 TWh in 2050, or it can be said that the demand will increase for about 9 times from the electricit y demand in 2018 in the amount of 254,6 TWh. The growth rate of electricity demand may reach an annual average score of 7% over the 20 18- 2050. The electricity demand during the projection period is relatively common with the largest portion of the household sec tor, industrial sector, commercial sector, transportation sector, and other sectors. The share of household electricity sector wil l increase from 49% in 2018 to 58% in 2050. This condition is primarily affected by the household growth number which may increase from 67 million in 2018 to approximately 80 million in 2050 [1, 2]. The decrease in fossil energy production especially petroleum and global commitments in reducing greenhouse and gas emission has driven the Indonesian government to intensify important and sustainable roles in new and re newable energy as part of maintaining energy autonomy and endurance [3]. In accordance with PP regulation number 79 of 2014 concerning the National Energy Policy, the targetted new and renewable energy combination in 2025 is at least 23% and in 2050 is at least 31%. Indonesia has big pot ency on new and renewable energy which will be achievable and meet the primary target. Indonesia has a total renewable energy potential equivalent to 442 GW which can be used for electricity generation, whereas the utilization is only 8.8 GW or it is only 0.019 % of the total renewable energy in 2018 [2]. The biggest potential for renewable energy may come from solar energy at 207.8 GWp. To accelerate New and Renewable energy development, the government has established several regulations such as Peraturan Presiden No. 4 in 2016 (Article 14) concerning the Electricity Infrastructure Acceleration prioritizing the use of new and re newable energy Peraturan Menteri ESDM No. 50 in 2017 concerning the Utilization of Renewable Energy Sources as the Supply of Electricity and Peraturan Menteri ESDM No. 49 in 2018 concerning the Use of Rooftop Solar Power Generation System by state -owned corporation Perusahaan Listrik Negara (PLN) customers [4-6]. With the high potential of solar energy in Indonesia and the indorsement from government regulations, this system is expected to be a solution to comply with the high electricity demand in the future by utilizing the solar cell as the source of electrical energy. By considering the growing number of household customers, utilizing the rooftop’s consumers as solar power generator base can be an effective and efficient solution. Therefore, the pu rpose of this research is to analyze the energy produced by rooftop solar power plant system with a household-scale on-grid system with simulation in PVSyst 6.43 software and to analyze the economic feasibility of rooftop solar power plant on grid system household -scale. 2. Material and Methods 2.1. Solar Radiation Solar radiation is defined as the amount of energy received per unit area and time on earth. The value can be determined depending on such factors, for instance, the location latitude, the season and weather, and the timing. There are two types of radiation which are direct radiation generated from the sun, and indirect radiation generated from atmospheric particles scattering. In donesia is geographically located on the equator in exact and this resulting in such advantages and great potential of solar energy utilization. Indonesia has a relatively high radiation level which is equal to 4,80 kWh/m2/day [7-9] 2.2. Solar Power Plants Solar Power Plant is a sunlight-based power plant that uses solar cells to convert the photon sunray radiation into electricity. Solar cells are made from sheer layers of pure silicon and such semiconductor materials. Solar Power Plants is friendly to th e environment and it does not produce any noise nor harmful waste to the surroundings. There are several factors that influence the solar cell output power efficiency such as solar radiation, solar cell temperature, solar panel orientation, and shadow leverages [10-12]. 2.3. Technical Analysis The technical analysis is conducted based on the rooftop solar power plant capacity, major components specification utilizati on and determination, solar panel orientation, and the generated power from the plant. The power generated by rooftop sola r power plant is affected by some factors including sunray radiation in the research area, the solar panel slope and its direction, sunligh t, temperature, and the technical performance [13]. This technical performance is predicted to decrease in time because of the solar module degradation [14]. The quality of rooftop solar power plant can also be seen by its performance ratio. In general, performance rati o is shown in percentage value that shows the total power produced by the system and also the losses compared while the system is working in STC condition. Solar power plant losses are due to solar panel efficiency, temperature, and inverter efficiency [15, 16]. 2.4. Economic Feasibility Analysis In general, economic analysis can be defined as an economical analysis of technical investment. The purpose of this analysis is to assess the technical investment proposal feasibility by doing an alternative study that is considered the most profitable. Ba sically, technical investments have a long economic cycle, mostly it has an annual cycle length. On the other hand, the currency value s vary time after time. Therefore, the equivalence currency value process is needed [17]. Research on the economic solar cell energy based uses some methods, which are Net Present Value (NPV) and Discounted Payback Period (DPP). Economic research should be conducted due to fairly high expenses in order to find out the optimal and economic result. 2.5. Net Present Value (NPV) NPV is a method of calculating the net present value. The present assumption is to explain the initial time of the calculation to coincide with when the evaluation was carried out or in the zero year period (0) in the calculation of investment cash flow [18]. Cash mailto:jakawindarta@lecturer.undip.ac.id 15 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 5, No. 1: 14-20, 2021 DOI: 10.33805/2576-8484.189 © 2021 by the authors flow consists of cash in and cash out, Cash flow that only calculated the benefits is called the Present Worth of Benefit (PWB), whereas if cash flow only calculated cost is called the Present Worth of Cosf (PWC). Meanwhile, NPV is obtained from PWB -PWC. To calculate the PWB, PWC, and NPV values, the following equation is used: 0 ( ) n t t t PWB Cb FBP = = (1) 0 ( ) n t t t PWC Cc FBP = = (2) NPV PWB PWC= − (3) Which Cb is Cash flow benefit, Cc is Cash flow cost, FBP is Present Interest Factor, t is Time Period, n is Age of investment . If the NPV value is more than 0, it means that the investment is feasible, whereas if the NPV value is less than 0, it means that the investment is unfeasible [18]. 2.6. Benefit Cost Ratio (BCR) The benefit cost ratio (BCR) method is one of the methods often used in the initial evaluation stages of investment planning or as an additional analysis in order to validate the evaluation results that have been done with other methods. To calculate the value of bcr used equations as follows: PWB BCR PWC = (4) Where PWB is Present worth Benefit and PWC is Present worth Cost. To find out if an investment plan is economically viable or not, a specific measure/criterion is required in the BCR method if BCR is more than 1, it means that the investment is feasible. If BCR is less than 1, it means that the investment is unfeasible. 2.7. Payback Period (PP) Payback period (PP) is the time required to return the investment cost. The way to calculate the PP is to calculate the time needed (years) so that the estimated cumulative cash flow will be the same as the initial investment cost. To calculate the return period used, the calculation is as follows: 0 0 k t t PP CF = =  (5) Where PP is Payback Period, k is Period, CFt is Cash flow period -t. If the PP time period is shorter than the project life, the project investment will be feasible and if the PP time period is longer than the project life, the project investment is not feasible. 2.8. Internal Rate of Return (IRR) This Internal Rate of Return (IRR) method looks for interest rates when npv is equal to zero. So, in this IRR method the resulting information relates to the level of cash flow capability in returning the investment described in the form of a period of time. The simple logic explains how much cash flow is capable of returning its capital and how much liabilities it must meet. If th e value of the IRR is greater than the interest rate used in the calculation then it can be said to be feasible. 3. Results and Discussion 3.1. Simulation To stimulate the solar power plant prototype design on PVSyst 6.43, such data are required, for instance, the factors that af fect PVSyst 6.43 software simulation result. The factors are including the solar power plant geographic location, solar energy pot ential data, ambient temperature, solar panel orientation, specifications of the components used, and the daily load estimation. Af ter the simulation process is conducted, the amount of potential electrical energy will be shown. There are numerous values that indi cate the amount of produced electrical power, the amount of electricity delivered to the load, and the amount of electric p ower supplied to the grid. In addition, the solar power plant loss diagram and performance will be shown in graphical data. In this research, a household- scale rooftop solar power plant is designed in Sambiroto Asri Cluster residence number A.9 in Semarang City, Indonesia (Figure 1,2). Figure 1. Research location in sambiroto asri cluster residence number A9, Semarang City. Figure 2. Visualization of the research area located in Sambiroto Asri Cluster Residence, Semarang city. The research area is located astronomically in 7°1'56.06" South Latitude and 110 °27'28.58" East Longitude. According to NASA Prediction of Worldwide Energy Resources data, sun insolation in 2019 in this area is 5,59 kWh/m 2/day. Moreover, Semarang city ambient temperature data is collected also. The data mentioned above can be used to generate the result of potential electric ity production of a rooftop solar power plant in the research area [19] (Table 1). Table 1. Monthly insolation and temperature in site location. Month Insolation (kWh/m2.day) Temperature (°C) January 4,60 27,6 February 5,29 27,9 March 4,55 27,6 April 5,08 28,7 May 5,41 29,0 June 5,14 28,3 July 5,37 27,7 August 5,94 28,0 September 6,49 28,8 16 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 5, No. 1: 14-20, 2021 DOI: 10.33805/2576-8484.189 © 2021 by the authors October 6,54 29,8 November 6,02 30,1 December 5,30 28,7 According to the real condition in the research area, the planning of the Rooftop Solar Power Plant utilizes a fixed tilted plane with such adjustment to the rooftop condition for about 30° slope and -100° azimuth (Figure 3). Figure 3. Solar module orientation. The major components are solar panels and inverters. Each component consists of two alternative options. Solar Panel alternative option is polycrystalline or monocrystalline solar panel with 405 Wp capacity, while the inverter alternative option chosen f or this research is an inverter with more than 97% efficiency. The alternative component options u sed for Solar Power Plant will be assigned into PVSyst 6.43 software and it will be stimulated in the Rooftop Solar Power Plant planning as explained below (Table 2-5). Table 2. Solar Panel Specification Variation 1 (Canadian Solar CS3W405P). Specification Value Power Maximum (Pmax) 405 Wp Open Circuit Voltage (Voc) 47,4 V Short Circuit Current (Isc) 10,98 A Maximum Point Voltage (Vmp) 38,9 V Maximum Point Current (Imp) 10,42 A Module Efficiency 18,3 % Dimension (mm x mm x mm) 2108 x 1048 x 40 Price IDR 3.900.000 Table 3. Solar panel specification variaton 2 (Risen Solar RSM144-6-405M). Specification Value Power Maximum (Pmax) 405 Wp Open Circuit Voltage (Voc) 48,75 V Short Circuit Current (Isc) 10,60 A Maximum Point Voltage (Vmp) 40,55 V Maximum Point Current (Imp) 10:00 AM Module Efficiency 20,2 % Dimension (mm x mm x mm) 2015 x 996 x 40 Price IDR 4.400.000 Table 4. Inverter specification variation 1 (Solax X1-1.1-S). Specification Value Input DC Maximum Solar Array Power 1250 W Maximum DC Voltage 400 V Maximum Input Current 12:00 AM MPPT Voltage Range 55-380 V Output AC Maximum Output Power 1100 W Grid Voltage Range 180-280 V Maximum Output Current 5,5 A General Data Maximum Efficiency 97,1 % Dimension 267 x 328 x 116 mm Price IDR 6.000.000 Table 5. Inverter specification variation 2 (Sofar 1,1 kW). Specification Value Input DC Maxiumum Solar Array Power 1500 Wp Maximum DC Voltage 500 V Maximum Input Current 12:00 AM MPPT Voltage Range 50-500 V Output AC Maximum Output Power 1100 W Grid Voltage Range 150-276 V Maximum Output Current 5,3 A General Data Maximum Efficiency 97,5 % Dimension 260.5 x 303 x 118 mm Price IDR 6.300.000 According to component alternatives above, Rooftop Solar Power Plant that will be stimulated have four different configurations as shown in Table 6 below. 17 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 5, No. 1: 14-20, 2021 DOI: 10.33805/2576-8484.189 © 2021 by the authors Table 6. Solar power plant variation. Variation Solar Panel Inverter Array Configuration 1 Canadian Solar Polycrystalline 405 Wp Solax X1-1.1-S 3 series of installed modules Voc (47,4 V) Max Vin (400 V) Voc (142,2 V) Isc (10,98 A) Max Iin (12 A) Isc (10,98 A) 2 Canadian Solar Polycrystalline 405 Wp Sofar 1100TL-G3 3 series of installed modules. Voc (47,4 V) Max Vin (500 V) Voc (142,2 V) Isc (10,98 A) Max Iin (12 A) Isc (10,98 A) 3 Risen Solar Monocrystalline 405 Wp Solax X1-1.1-S 3 series of installed modules. Voc (48,75 V) Max Vin (400 V) Voc (146,25 V) Isc (10,6 A) Max Iin (12 A) Isc (10,6) 4 Risen Solar Monocrystalline 405 Wp Sofar 1100TL-G3 3 series of installed modules. Voc (48,75 V) Max Vin (500 V) Voc (146,25 V) Isc (10,6 A) Max Iin (12 A) Isc (10,6) Estimated daily load data in the research area is generated manually and periodically to obtain an exact daily load profile data. The research area has an installed electrical capacity of 1300VA. The following figure will display the daily load profile in the research area (Figure 4,5). Figure 4. Daily hourly profile distribution in the research area Working Days. Figure 5. Daily hourly profile distribution in the research area Week Ends. The simulation utilizing PVSyst 6.43 software can be conducted after determining and inputting all data. 3.2. Results The result of PVSyst 6.43 simulation on household-scale rooftop solar power plant planning variations 1, 2, 3, and 4 can be seen in the figures below (Figures 6-9). Figure 6. Variation 1 Results. Figure 7. Variation 2 Results. Figure 8. Variation 3 Results. 18 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 5, No. 1: 14-20, 2021 DOI: 10.33805/2576-8484.189 © 2021 by the authors Figure 9. Variation 2 Results. 3.3. Technical Analysis Based on the simulation results of PVSyst 6.43 software of each household-scale rooftop solar power plant in the research area, Table 7 is aimed to show each variations results as follows. Table 7. The result of PVSyst 6.43 simulation in Rooftop Solar Power Plant Variation 1, 2, 3, and 4. Variation Solar Panel Insulation (kWh/m2) STC Array Electric Energy (kWh) Array Output Electric Energy (kWh) Inverter Output Electric Energy (kWh) Performance Ratio (%) Variation 1 1862,1 2195 1954 1873 82,8 Variation 2 1862,1 2195 1954 1893 83,7 Variation 3 1862,1 2196 1946 1865 82,4 Variation 4 1862,1 2196 1946 1885 83,3 It can be concluded from Table 8 that the production sunray array electric energy production in variation 1 and 2 have smalle r value in the amount of 2195 KWh per year rather than the variation 3 and 4 which equal to 2196 KWh per year. Thus, it has 1 KWh deviation caused by the solar panel efficiency and surface area used in this research. The variation 1 and 2 utilize Canadian Solar Panel type CS3W405P with an efficiency value of 18.3% and it has surface area of 6,63 m 2 which produces electrical energy output array of 2195 KWh during STC condition. On the other hand, the variation 3 and 4 utilize Risen Solar Panel with an efficiency value of 20,2% and it has surface area of 6,02 m2 which produces electrical energy output array of 2196 KWh. Therefore, it can be concluded that the greater solar panel e fficiency and the larger solar panel surface area will be resulting in better results. The efficiency is also depending on the type of solar panel. Monocrystalline solar panel types generally have better efficiency because the primary material for making p anel which is silicone has greater concentration rather than the polycrystalline type [20]. However, at the same rated power, monocrystalline types have smaller panel surface area than the polycrystalline types. The annual array output for electrical energy in variation 1 and 2 suffered losses from STC conditions of 241 kWh from the STC condition so it becomes 1954 kWh. Moreover, the annual array output for electrical energy in variation 3 and 4 suffered losses from STC conditions of 250 kWh from the STC condition so it results of 1946 kWh. It can be said that these solar panel types have simi lar losses characteristics for about 9 kWh adrift. If variation 1 and 2 is compared by also looking at the same type of panels, the output electric energy in variation 2 is larger than variation 1. This due to the usage of Sofar Inverter which has efficiency rate of 97.5% in variation 2 is bigger than the usage of Solax inverter X1-1.1-S type which has efficiency rate of 97.1%. This also can be seen in variation 3 and 4. The output electric energy in variation 4 is larger than variation 2. This due to the usage of Sofar Inverter which has efficiency rate of 97.5% in variation 4 is bigger than the usage of Solax inverter X1 -1.1-S type which has efficiency rate of 97.1%. Hence, it could be said that the inverter with a bigger efficiency produces a bigger electrical output as well. It can be concluded that the variation with the biggest performance ratio is variation 2 which has 83.7% ratio, and the smallest performance ratio is variation 3 which has 82,4% ratio. 3.4. Economic Analysis The feasibility of the rooftop solar power plant that will be designed in the research area will be determined by Net Present Value (NPV) and Benefit Cost Ratio (BCR). While, the best variation will be determined Payback Period (PP) dan Internal Rate of Ret urn (IRR) method. The simulation result is affected by the total investment costs, operational costs, saving costs and electricity sales, discount rates, and inflation values. The total investment cost of each variation is obtained from surveys to several offline stores in Semarang city and also nume rous e-commerce stores in Indonesia, while the discount rate and inflation value are obtained from the official website of Bank Indonesia [21]. The investment costs for each component in the design of a household-scale rooftop solar power plant system variations 1, 2, 3, and 4, can be seen in the Tables 8-11 below. Table 8. Initial investment cost of Rooftop Solar Power Plant Variation 1. Component Amount Unit Price Total Price Canadian Solar Panel 3 Module IDR 3.900.000 IDR 11.700.000 Solax Inverter 1 Piece IDR 6.000.000 IDR 6.000.000 Solar Panel Mounting 1 set IDR 1.107.000 IDR 1.107.000 Solar Panel Grounding 1 set IDR 360.000 IDR 360.000 Cable 1 set IDR 420.000 IDR 420.000 Protection 1 set IDR 643.000 IDR 643.000 Service and others 1 set IDR 4.990.000 IDR 4.990.000 Total IDR 25.220.000 Table 9. Initial investment cost of Rooftop Solar Power Plant Variation 2. Component Amount Unit Price Total Price Canadian Solar Panel 3 Module IDR 3.900.000 IDR 11.700.000 Solax Inverter 1 Piece IDR 6.300.000 IDR 6.300.000 Solar Panel Mounting 1 set IDR 1.107.000 IDR 1.107.000 Solar Panel Grounding 1 set IDR 360.000 IDR 360.000 Cable 1 set IDR 420.000 IDR 420.000 Protection 1 set IDR 643.000 IDR 643.000 Service and others 1 set IDR 4.990.000 IDR 4.990.000 Total IDR 25.520.000 19 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 5, No. 1: 14-20, 2021 DOI: 10.33805/2576-8484.189 © 2021 by the authors Table 10. Initial investment cost of Rooftop Solar Power Plant Variation 3. Component Amount Unit Price Total Price Risen Solar Panel 3 Module IDR 4.400.000 IDR 13.200.000 Solax Inverter 1 Piece IDR 6.000.000 IDR 6.000.000 Solar Panel Mounting 1 set IDR 1.107.000 IDR 1.107.000 Solar Panel Grounding 1 set IDR 360.000 IDR 360.000 Cable 1 set IDR 420.000 IDR 420.000 Protection 1 set IDR 643.000 IDR 643.000 Service and others 1 set IDR 4.990.000 IDR 4.990.000 Total IDR 26.720.000 Table 11. Initial investment cost of Rooftop Solar Power Plant Variation 4. Component Amount Unit Price Total Price Risen Solar Panel 3 Module IDR 4.400.000 IDR 13.200.000 Solax Inverter 1 Piece IDR 6.300.000 IDR 6.300.000 Solar Panel Mounting 1 set IDR 1.107.000 IDR 1.107.000 Solar Panel Grounding 1 set IDR 360.000 IDR 360.000 Cable 1 set IDR 420.000 IDR 420.000 Protection 1 set IDR 643.000 IDR 643.000 Service and others 1 set IDR 4.990.000 IDR 4.990.000 Total IDR 27.020.000 After the initial investment cost is calculated, then the annual operational and maintenance cost will be estimated. The estimated cost of the Solar Power Plant system will be approximately 1-2% from the total initial investment cost so that the annual operational cost estimation can be seen in tables 12, 13, 14, and 15 below. Table 12. Operational Cost of Solar Power Plant system Variation 1. Component Amount Unit Price Total Price O and M Solar Panel 1 Year IDR117.000 IDR117.000 O and M Inverter 1 Year IDR60.000 IDR60.000 O and M Solar Panel Mounting 1 Year IDR11.070 IDR11.070 O and M Solar Panel Grounding 1 Year IDR3.600 IDR3.600 O and M Cable 1 Year IDR4.200 IDR4.200 O and M Protection 1 Year IDR6.430 IDR6.430 Total IDR202.300 Table 13. Operational Cost of Solar Power Plant system Variation 2. Component Amount Unit Price Total Price O and M Solar Panel 1 Year IDR117.000 IDR117.000 O and M Inverter 1 Year IDR63.000 IDR63.000 O and M Solar Panel Mounting 1 Year IDR11.070 IDR11.070 O and M Solar Panel Grounding 1 Year IDR3.600 IDR3.600 O and M Cable 1 Year IDR4.200 IDR4.200 O and M Protection 1 Year IDR6.430 IDR6.430 Total IDR205.300 Table 14. Operational Cost of Solar Power Plant system Variation 3. Component Amount Unit Price Total Price O and M Solar Panel 1 Year IDR132.000 IDR132.000 O and M Inverter 1 Year IDR60.000 IDR60.000 O and M Solar Panel Mounting 1 Year IDR11.070 IDR11.070 O and M Solar Panel Grounding 1 Year IDR3.600 IDR3.600 O and M Cable 1 Year IDR4.200 IDR4.200 O and M Protection 1 Year IDR6.430 IDR6.430 Total IDR217.300 Table 15. Operational Cost of Solar Power Plant system Variation 4. Component Amount Unit Price Total Price O and M Solar Panel 1 Year IDR132.000 IDR132.000 O and M Inverter 1 Year IDR63.000 IDR63.000 O and M Solar Panel Mounting 1 Year IDR11.070 IDR11.070 O and M Solar Panel Grounding 1 Year IDR3.600 IDR3.600 O and M Cable 1 Year IDR4.200 IDR4.200 O and M Protection 1 Year IDR6.430 IDR6.430 Total IDR220.300 According to Minister of Energy and Mineral Resources Regulation No. 49 in 2018 article 6, it is stated that the electrical e nergy from Rooftop Solar Power Plant usage by PLN customers will be calculated based on the export kWh recorded on the export -import kWh meter multiplied by 65% of the applicable electricity tariff. For the building as the research area is included in the S1 type, the applicable tariff would be IDR 1.467/kWh. Therefore, 65 % of IDR1.467/kWh is IDR 953,55/kWh. This resulting in the estimated annual electricity savings and sales variation that can be seen in tables 16, 17, 18, and 19 as follows. 20 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 5, No. 1: 14-20, 2021 DOI: 10.33805/2576-8484.189 © 2021 by the authors Table 16. Solar Power Plant system Revenue Variation 1. Component Amount Unit Price Total Price Electrical Energy Saving 909,97 Year IDR 1.467 IDR1.334.926 Electrical Energy Selling 962,7 Year IDR 953,55 IDR917.983 Table 17. Solar Power Plant system Revenue Variation 2. Component Amount Unit Price Total Price Electrical Energy Saving 909,97 Year IDR 1.467 IDR1.347.043 Electrical Energy Selling 962,7 Year IDR 953,55 IDR929.711 Table 18. Solar Power Plant system Revenue Variation 3. Component Amount Unit Price Total Price Electrical Energy Saving 909,97 Year IDR 1.467 IDR1.332.403 Electrical Energy Selling 962,7 Year IDR 953,55 IDR912.357 Table 19. Solar Power Plant system Revenue Variation 4. Component Amount Unit Price Total Price Electrical Energy Saving 909,97 Year IDR 1.467 IDR1.344.579 Electrical Energy Selling 962,7 Year IDR 953,55 IDR923.895 The implied electrical energy saving is electricity produced from solar panel and it is used separately to supply the home loads needs in accordance with the PVSyst 6.43 software simulation result, whereas the intended electrical energy selling is electr icity produced from solar panels and distributed to the grids. By using simulation results, the NPV, BCR, PP, and IRR values for ea ch variation are as follows. Table 20. NPV, BCR, PP and IRR value Variation 1, 2, 3 and 4. Method Variation 1 Variation 2 Variation 3 Variation 4 NPV IDR17.289.694 IDR17.421.839 IDR15.309.805 IDR15.439.213 BCR 1,588 1,585 1,49 1,489 Payback Period 10,38 10,39 11,01 11,02 IRR 9,56 9,54 8,81 8,8 According to Table 20, it is shown that NPV value in each variations has more than 0 value dan BCR in each variation has more than 1 value. Therefore, it can be said that the housing-scale rooftop solar power plant investment for each variations are feasible. While the best variation is variation 1 because it has smallest PP value dan biggest IRR value compared to other variations. 4. Conclusions The solar power plant system designed in this research is connected to the grid. The rooftop solar power plant planning has f our different variations which utilizes 3 solar panels with a capacity of 405 Wp and a 1100 W inverter. The electricity produced from this household-scale rooftop solar power plant in the research area is ranging from 1865-1893 kWh with a performance ratio ranging from 82,4-83.7%. Based on the performance ratio result, the most efficient variation is variation 2 with an 83.7% performance ratio value. 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