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Indonesia is driving the implementation of renewable energy to meet its climate action goals.Solar energy resources are abundant, and the use of solar energy is prioritized, including rooftop solar power plants (RSPP).This study conducts a techno-economic analysis of the RSPP installed in a mosque in the Ngombol sub-district, Purworejo district, Central Java, Indonesia.This paper also introduces and explains Indonesia’s regulation of RSPP and electricity prices, which define the economics of RSPP.This study analyzes RSPP in five scenarios using operational and financial models.The RSPP is designed to reduce the mosque’s annual energy use and generate the highest net present value (NPV).Based on the results​​, RSPP for all configurations based on panel type and quantity yields a negative NPV under current electricity prices, component costs and implemented regulations regarding RSPP.Proposed policy adjustments modeled through different scenarios provide benefits to some extent, but are limited by other policies.Therefore, a combination of different policy adjustments may be required to achieve optimal conditions for implementing RSPP on mosque roofs.This research can help policymakers understand possible directions for policy design to accelerate PV implementation.
In terms of renewable energy potential, Indonesia has a total capacity of 417.6 GW from different sources such as tidal, geothermal, biomass, wind, hydro and solar.207.8 GW or roughly half of that capacity comes from solar energy, thanks to its geography as it crosses the equator2.This capacity potential is even more significant relative to the total generation in June 2020, which was only 71 GW3.By early September 2021, Indonesia’s solar implementation was only 0.08% of its potential, with an installed capacity of 150 MWp4.This utilization rate is relatively low because Indonesia’s energy sector is still dominated by fossil fuels.In 2020, fossil fuels supported 88.8% of primary energy supply and 85.3% of electricity generation3,5.This situation has resulted in high greenhouse gas (GHG) emissions from the energy sector, accounting for approximately 30-40% of Indonesia’s total GHG emissions.Renewable energy is known as a low-carbon alternative to fossil fuels.Tavarbe et al.The carbon footprint of solar energy is estimated to be in the range of 14-73 g CO2-eq/kWh, which is only 2% to 10% of the carbon emitted by oil-fired electricity generating 1 kWh7.Therefore, as part of its climate action, Indonesia aims to increase the share of renewable energy in its primary energy supply mix to 23% by 20251.
To achieve this, the Government of Indonesia (GOI) plans to increase the installed capacity of solar power plants (SPPs) to 3.6 GWp by 2025, including large-scale SPPs, rooftop SPPs (RSPPs) and floating SPPs8.The Institute for Essential Services Reform (IESR), an energy and environment think tank, has raised the possibility that Indonesia could achieve its energy transition goals by utilizing distributed solar power in the form of rooftop and off-grid SPPs.IESR further estimates that there is a minimum potential of 2 GWp RSPP in the residential markets in Jakarta and Surabaya9.When considering other cities and building types, this research implies even greater potential.There is also growing interest in research on RSPP design in Indonesia, where RSPP for residential 10, 11, offices 12, 13, education 14, 15, 16 and industrial buildings 13 are analysed.This article will focus on SPP on mosque roofs because of its significance in the Indonesian context, and this type of building has not received the same research attention as other buildings.
Indonesia has one of the largest Muslim populations in the world.For this reason, the Ministry of Religious Affairs reported over 600,000 mosques and prayer halls of various sizes to support their activities17.Muslims gather at the mosque at five designated times each day (before dawn, noon, afternoon, sunset and evening), with higher visits at noon on Fridays.The sheer number of mosques indicates a large cumulative roof area, and the frequent use of mosques may result in significant electricity consumption, demonstrating the potential of RSPP implementation.In 2017, the Vice President of Indonesia and the Indonesian Council of Clergy Majelis Ulama Indonesia (MUI) launched the Eco-Mosque Initiative, which aims to increase environmental awareness in the community through the use of renewable energy, energy efficiency, waste management and water conservation in mosques18 .The roof area of ​​the mosque is relatively large, which is suitable for installing RSPP.RSPP can provide mosques with clean electricity at relatively low operating and maintenance expenditures (OPEX), thereby reducing electricity bills and GHG emissions from a financial and environmental perspective.Higher electricity prices and declining capital expenditures (CAPEX) on technology make the business case for RSPP more attractive19.According to Ghazali et al., the use of clean energy in such buildings is also ethically and morally relevant, as protection of nature and the environment is one of the teachings of Islam, as indirectly implied by the religion’s holy book 20.
In a broader context, the adoption of solar photovoltaics is well suited for rural electrification through microgrids.Due to its decentralized nature, microgrids are an economical option for electrification in remote areas rather than extending centralized grids21,22.Microgrids with decentralized power generation, such as SPPs, yield several advantages, such as reduced energy losses, more reliable supply, and reduced carbon emissions, due to the higher adoption of renewable energy sources23,24.The mosque is ideally used as a place of worship and as a community building centre for its surroundings25.Especially in rural areas, this purpose can be further enhanced by combining mosques with decentralized power generation and connecting them through microgrids.
As will be discussed briefly in this article, there has been a great deal of research into the implementation of rooftop solar photovoltaics in mosques.Rashid et al.Demonstrates the RSPP’s ability to reduce Malaysia’s annual electricity bill by 47%28.The CAPEX payback period for the system is 13 years.Almutairi also conducted a similar study in Kuwait to determine the financial viability of the RSPP at 1,400 mosques in 2018 and documented the exact payback period29.Photovoltaic systems are designed to power connected loads and reduce peak loads during the day.However, it is important to note that both studies did not consider the present value of future cash flows, which means that the benefits of the system may be overestimated and the actual payback period is realized later.
In 2019, Elshurafa et al.A more comprehensive pilot study of the mosque RSPP in Saudi Arabia19 was conducted.RSPP grid connection is suitable for different scenarios, including no support policy and net metering mechanism, which can compensate for the remaining power output to the grid.The results show that the analyzed systems are financially attractive in both cases.The study found that the systems analyzed were economically attractive in both cases.The implementation of net metering reduces the cost of meeting electricity demand by 22% compared to the RSPP without the Supporting Policy Scenario.
The GOI has regulated the RSPP through Ministerial Regulation No. 49/2018 of the Minister of Energy and Mineral Resources (MEMR) to support the implementation of the technology30.Among other things, the regulation includes Indonesia’s RSPP’s net metering scheme, which enables consumers with RSPP to export their excess produced energy to the grid owned by state power utility Perusahaan Listrik Negara (PLN).Exported electricity will be offset from imported electricity from the PLN and calculated monthly.Consumers can offset 65% of the electricity exported each month.The PLN believes that this arrangement is to take into account transmission and distribution costs31.In the case of high exports, the export balance can accumulate for three months, after which the balance is reset to zero.The regulation also specifies the maximum capacity of the RSPP, which is 100% of the contracted electricity capacity.However, the report suggests that despite the government’s intention to accelerate the implementation of the RSPP, the regulation has failed to realize the economic benefits of installing the RSPP.According to simulations by the Institute for Energy Economics and Financial Analysis (IEEFA), consumers will have difficulty estimating the size of their SPP to maximize savings, which is also sensitive to consumers’ daytime load conditions31.Their results suggest that the policy favors consumers with high daytime load profiles and minimal output to the grid, contrary to its goal of encouraging RSPP through the ability to output to the grid.This load curve is uncommon because most consumers, especially those in the residential sector, have higher load curves at night.
Setyawati examined perceptions of Indonesia’s current RSPP regulations through interviews and an online survey32.The findings suggest that both consumer and institutional barriers limit the implementation of the RSPP under current policies.71% of the 987 PLN customers surveyed were interested in installing RSPP, but were more willing to wait for other options, meaning the current policy was less attractive.Consumers worry about high capital costs, long-term return on investment and lack of information.Through interviews with the government, the private sector and energy experts, Setyawati found that low electricity export rates are a major barrier to attracting potential users.
The initial investment for CAPEX and electricity savings is a function of electricity price, which defines the general return on investment for SPP, including RSPP.In Indonesia, MEMR determines the price of electricity provided by PLN through ministerial regulations, which are updated from time to time33, 34, 35, 36.There are 37 electricity prices grouped by consumer sector (residential, social, industrial, commercial, and government) and by size of electricity capacity, denoted by VA37.Of the 37 electricity price groups, 25 are subsidized, including electricity prices for all consumers in society.The Biaya Pokok Produksi (BPP), determined by the MEMR Ministerial Decree, has reduced the electricity price in the social sector by about 35%38 compared to the basic production cost of electricity generation.Therefore, electricity tariff subsidies for social sector consumers may hinder the ability of RSPP to recoup its initial investment in Indonesian mosques due to lower electricity bill savings.Electricity tariff regulations also mandate a minimum of 40 hours of use per month, which prevents consumers from avoiding electricity bills entirely, although RSPP production is more than enough to offset imports.Referring to IEEFA’s analysis, consumers in the social sector will find it more challenging to size the RSPP to maximize savings on electricity bills.
There are several ways to determine the size of the SPP.Some SPP design and analysis studies have used commercial software such as Homer12, 19, 39, PVsyst10, 11, 16, 29, SOLARGIS pvPlanner10, 14, RETSreen10 and the System Advisory Model (SAM)13.Šimić et al.A method for determining the economically optimal SPP size based on Croatian policy is proposed40.The price of electricity produced by SPP depends on the ratio of imports and exports.This policy enforces lower prices for electricity generated by SPP and lowers revenue with a higher export ratio.Therefore, an excessively large SPP could adversely affect the financial viability of the SPP.
This study aims to conduct a similar analysis to that mentioned in the previous related study, which includes exploring the design and feasibility of location-based mosque RSPP and Indonesia’s effective regulation of RSPP as a case study.As mentioned above, the current policies surrounding the implementation of RSPP in Indonesia are somewhat unsupportive.Therefore, four different policy scenarios are proposed in the simulation to better realize the financial benefits of RSPP implementation.To this end, for the first time, we have conducted a detailed techno-economic analysis of RSPP in Indonesian mosques, and the findings are expected to serve two purposes.The first is to define the implementation of RSPP in a mosque in Indonesia.The second is to provide policymakers with insights into the effectiveness of current support policies for specific end-user-implemented systems.
The structure of this paper is four chapters.The first chapter introduces the introduction and literature review of related research.Chapter 2 elaborates the methodology and assumptions adopted in this paper.Chapter 3 presents the results of the design.Chapter 4 presents the discussion and conclusion of this paper.
This chapter describes the assumptions based on the case study, followed by the methodology employed, comprising three main activities: data collection, RSPP design, and analysis of design results.The analysis in each activity is done using code written in MATLAB.
Ontowiryo Mosque is located in Wonosari Village, Ngombol Street, on the south side of Purworejo District, Central Java Province, with a longitude of 109.96° and a latitude of -7.85°.The configurations of roof, azimuth, inclination and area are shown in Figure 1 and Table 1.The mosque is connected to a grid with a maximum power capacity of 5,500 VA.The installation of RSPP at the mosque further enhances its use as a community center, such as providing street lighting for its surroundings, as such services are lacking in the vicinity of the case study.This purpose is interesting for further research, as the RSPP analyzed in this paper is limited to providing energy use for mosques, as described in the next section.
(a) Map of India showing the location of the Ontowiryo Mosque, modified from FreeVectorFlags.com using CorelDRAW 201841,42, (b) Google Maps image showing the mosque facing southwest.The mosque roof has two sides, west (W) and east (E).Image modified using CorelDRAW 201842, (c) South façade adapted from Detailed Engineering Design for Mosque 43.
The data acquisition process prepares the data required for the RSPP design process, including site condition data and hourly power load profile data.Site condition data comes from Solcast, which provides a comprehensive set of hourly site condition data44.The data includes air temperature, cloud opacity, diffuse horizontal irradiance (DHI), direct normal irradiance (DNI), global horizontal irradiance (GHI), solar azimuth, solar elevation, wind speed, relative humidity and precipitable water.Site condition data is available for selected locations for 12 years (2008-2019) or 4,383 days with 105,192 hours of data.
Figure 2a shows the average daily GHI over 12 years of data, which was relatively constant at an average of 5.4 kW/m2 per day.Slight fluctuations are due to seasonal differences between years, a year may have longer dry/wet seasons and vice versa.Indonesia’s dry season spans the middle of the year and the rest of the year is the rainy season.Figure 2b shows the change in irradiance throughout the year.The GHI was relatively stable, while higher DHI values ​​were observed at the end of the year and at the beginning of the year.This situation is due to more frequent rain and cloudy skies during the rainy season.Since the irradiance values ​​are relatively constant from year to year, the site condition data used in the design and simulation can be represented by data from one of the available years with the average daily GHI closest to the average.Therefore, the average daily GHI in 2008 was 5.41 W/m2 for design and simulation.Since 2008 was a leap year, only 365 days of data were used to simulate a year’s operation.
(a) Average daily GHI for each year between 2008-2019.(b) Average daily irradiance (DHI, DNI and GHI) for each month in 2008.
Ideally, hourly load profile data is generated from historical data by sampling electricity usage over the course of a day.Since the mosque is currently under construction, this method is not applicable to the case study considered.Therefore, the load situation of the mosque is estimated by calculating the lighting and electronic equipment that may be used for specific activities and specific times listed in Tables 2 and 3.The list of lighting used in each room comes from the detailed engineering design of the mosque.Appliances used in the operation of the mosque include sound systems, table tops, routers, refrigerators, vacuum cleaners and water pumps.
The final load curve of the mosque is shown in Fig.3.The electricity consumption of the mosque is 16.89 kWh/day and 6,166.49 kWh/year.All in all, this research effort with 8,760 hours of data simulates the full year operation of the RSPP.
The solar irradiance received by the roof area arrives in three forms: direct irradiance (\({G}_{M}^{dir}\)), diffuse irradiance (\({G}_{ M}^{dif}\ )), and the irradiance reflected by the ground (\({G}_{M}^{ground}\))45.Solar irradiance data (DNI, DHI, and GHI) obtained in previous campaigns are used to calculate each of these forms.Equation (1) defines the direct irradiance, where \(\gamma\) is the angle of incidence (AOI), which is the angle between the PV module surface normal and the direction of incidence of sunlight.Given the changing sun position, the AOI is panel azimuth\({A}_{M}\), panel elevation\({a}_{M}\), sun azimuth\({A }_{ S}\) and the sun elevation angle\({a}_{S}\).Equation (2) defines \(\mathrm{cos}\gamma\).
Equation (3) defines the diffuse irradiance as a function of the sky view factor (SVF).SVF is the fraction of sky that the module can receive as diffuse irradiance, expressed as a formula.(4).Equation (5) defines the irradiance reflected by the ground, where \(\alpha\) is the ground albedo that determines the ground reflection coefficient.The total irradiance received by the module (\({G}_{M})\) is determined by adding the three components of irradiance to determine the irradiance received by the roof, resulting in a solar estimate for the mosque Yield roof.
This paper studies the grid-connected RSPP modeled in Figure 4.The system is modeled at hourly time steps for a one-year period, contains 8760 data steps, and is repeated over the 25-year (2021-2045) assumed lifetime of the RSPP46.The RSPP generated within one hour is calculated as module area, module number (\({n}_{M}\)), module received irradiance (\({G}_{M})\ ), inverter efficiency (\({\eta }_{inv}\)), module degradation rate (\({\eta }_{deg}\)), module efficiency (\({\eta }_{M }\) ), as shown in the equation.(7).Module efficiency is a function of module irradiance level and temperature (\({T}_{M})\) as shown in the equation.(8) Until 1245.
\(\eta \left(25^\circ{\rm C} , {G}_{M}\right)\), \({V}_{oc}\left(25^\circ{\rm C } , {G}_{M}\right)\) and \({I}_{sc}\left(25^\circ{\rm C} , {G}_{M}\right)\) are Module efficiency, open circuit voltage and short circuit current as a function of irradiance.The data obtained from the module data sheet are temperature coefficient (\(\kappa\)), open circuit voltage (Voc), short circuit current (Isc), module area and module degradation rate.The values ​​for Boltzmann constant (kb), elementary charge (q) and figure of merit (n) are from 47.FF is the fill factor, which is the ratio between the power produced at the maximum power point and the product of Voc and Isc.GSTC and TSTC are standard conditions for irradiance and temperature when testing PV modules, 1000 Wm-2 and 25 °C, respectively.The temperature of the module (\({T}_{M})\) is determined by a hydrodynamic model that takes into account the heat sources of solar radiation, convection, and radiative heat exchange from the front and rear sides of the module.Equations (13–25) give the computation of \({T}_{M}\),
where \({\alpha }_{M}\) is the absorption rate of the module, \({T}_{a}\) is the ambient temperature, \({h}_{c}\) is the transmission rate of the convection module Thermal coefficients, \({h}_{r,sky}\) and \({h}_{r,gr}\) are radiative heat transfer to the sky and ground or roof, just in case RSPP, \( {T}_{sky}\) and \({T}_{gr}\) are sky and ground temperatures.The process of finding the module temperature is an iterative process because \({h}_{r,sky}\) and \({h}_{r,gr}\) are \({T}_{ M}\) .\(Gr\) is the Grashof number, \(Pr\) is the Prandtl number, air is equal to 0.71, \(\sigma\) is the Stefan-Boltzmann constant, \({D}_{h}\) is the hydraulic diameter of a A rectangle with a width of \(W\) and a length of \(L\), \(k\) is the thermal conductivity of air, and \(v\) is the viscosity of air.\({T}_{INOCT}\) is the nominal operating battery temperature of the installation, which is equal to the equation for direct installation.(twenty three).\({\epsilon }_{back}\) and \({\epsilon }_{top}\) are the emissivity of the front and rear surfaces of the module, equal to 0.89 and 0.84, respectively.
The model’s algorithm compares the load from the RSPP with the energy produced hourly.When the load exceeds the RSPP generation capacity, the generated energy will be consumed while the energy is imported from the grid to supply the shortage.Vice versa, when the RSPP power generation is higher than the load, the excess energy produced will be exported to the grid.Equations (26 and 27) give the model import and export mechanism.According to the regulations, import and export electricity charges are accumulated every month to determine the monthly electricity charges.The PLN compensates 65% of the output energy to offset the input energy.The offset limit is that the reduced imported energy cannot be lower than the monthly minimum load, which is equal to the maximum electricity usage for 40 hours, that is, the monthly minimum load is 220 kWh or the annual minimum load is 2640 kWh (\({E }_{minimum load}\)) .If this limit is reached, the excess exports will be credited to the grid and offset imports for the next three months before being reset to zero.Due to the limitations of the model, the offsetting balance reset mechanism is not modeled, and the model accumulates imports and exports by year.Therefore, the model may fail to account for the loss of export deposits due to the reset mechanism.The net load, which is the load that is reduced due to the use of RSPP, can be obtained by offsetting the import with the compensated export, as shown in Equation 11.(28).This value will be used to calculate the annual revenue of the RSPP, as explained further in the financial model in Figure 5.
RSPP’s revenue is derived from the annual savings in electricity bills, calculated using the initial load after RSPP minus the final load multiplied by the electricity bill (\({C}_{el}\)).Each year, the financial model compares the net load to the regulatory minimum load for the assumed 25-year life of the RSPP.Due to the degradation rate of the modules, the net load is an annual function, while the minimum load is a constant.If the net load is higher than the minimum load, the bill is equal to the net load.Vice versa, when the net load is lower than the minimum load, the bill is equal to the net load and the excess is deposited into the grid.In fact, this excess can offset future imports when RSPP production is low.However, the model uses only one year of irradiance data and replicates these data over the assumed lifetime of the RSPP.Therefore, RSPP generation is relatively constant, and larger capacity RSPPs may result in the export of unused deposits.The RSPP’s annual revenue (\(R(Y)\)) as a share of the total annual cash inflow is obtained by subtracting OPEX from the annual electricity savings.Dagus et al.The estimated CAPEX and OPEX of Indonesian SPP are US$1365.76 per annum and US$24.38/kW48.The system’s net present value (NPV) is then calculated using the RSPP’s annual revenue and capital expenditures.According to a 2017 market study, a typical proportion of RSPP CAPEX in Indonesia consists of 47% of PV module cost, 13% of inverter cost and 40% of other complementary components and installation cost49.The cost of PV modules and inverters is estimated from Darguth et al. The paper is taken from the Renewable Energy Technology Distributors website.Lack of technical specification details required for simulation50.Like other renewable energy technologies, RSPP is capital intensive​​.Therefore, the lowest price/kW PV modules are used to reduce CAPEX, and this study uses Suntech STP375S 375 W.Each component was modeled in the simulation at various RSPP capacities, with a maximum power capacity of 5.5 kWh or cap.The study also employed nine different sized inverter types from Growatt by matching the power output requirements of each simulation.Capital expenditures include PV modules (\({C}_{PV}\)), inverters (\({C}_{ inv}\)) and other components and installations (\({C}_{other} \)) as shown in the equation.(31).Table 4 lists the price per kilowatt of PV modules, inverters, and other costs used in the calculations.Technical specifications of PV modules and inverters can be found online in Supplementary Tables S1 and S2.
The MEMR Ministerial Regulation regulates electricity prices in Indonesia.For social sector consumers with 5,500 VA of electricity capacity, the electricity price for the past eight years was 6.27 cents/kWh.The tariff is subsidized because it averages only 65% ​​of the BPP.PLN’s statistical report shows BPP values ​​for 2011-202,048,49, while PLN’s Electricity Supply Business Plan (RUPTL) shows forecasts for BPP values ​​from 2021 to 203050.BPP values ​​beyond 2030 estimate a regression function generated from known values ​​of BPP for 2015-2030 using a second-order polynomial.The decline in BPP in 2015 is due to improvements in the efficiency of the power system51. The surge in BPP in 2025 is due to a significant increase in the adoption of renewable energy to achieve the Paris Agreement for that particular year.BPP is expected to rise at a slower pace due to phasing out of coal PP starting in 2030 and falling costs of renewable energy technologies.Therefore, the projected electricity price from 2022 is set at 65% of the BPP shown in Figure 6.The currency exchange rates used in this article are 1 USD = 14,351 IDR, 1 GBP = 1.33 USD.
The financial model economic analysis uses the net present value method to estimate the economic value of the project outcome: positive or negative.The NPV integrates the initial investment and expected benefits and costs incurred during the operation of the RSPP into a series of cash flows adapted to the time value and risk of money.Equation (32) gives the NPV calculation53 for the 25-year operating life of the RSPP.The discount rate (\(r\)) is determined by the weighted average cost of capital (WACC).IRENA assumes an actual WACC of 7.5% for OECD countries and China, and 10% for the rest of the world, for all types of technologies54.The IEA assumes a WACC of 8% in developed countries and 7% in developing countries55.Steffen estimates the WACC for PV system development projects in and outside OECD countries to be 5.4% and 7.4%, respectively56.This paper uses the 7% WACC level as the discount rate.
As mentioned in the introduction, the current ecosystem may not be the best option for implementing RSPP in mosques.Therefore, several design scenarios were employed in the operational and financial models to explore financial viability options.
Business-as-usual (BAU) scenarios model RSPP with two goals: to have the highest NPV and to satisfy loads not covered by the minimum load limit.
The second scenario, the Carbon Pricing (CP) scenario, models RSPP and generates additional revenue from monetized carbon reductions.Climate Transparency estimates that about 761 grams of carbon dioxide is emitted into the air for 1 kWh of electricity generated in Indonesia57.The Environmental Protection Agency (EPA) uses three sets of estimates of the social cost of carbon emissions (SCC) at different discount levels, as shown in Table 5, SCC58 is the discounted monetary value of future climate change damage due to additional metric tons of carbon dioxide (CO2) emissions 59,60.Funds collected from carbon pricing can also finance the energy transition and subsidize the implementation of renewable energy.This article uses the SCC’s 5% discount factor, which is the closest to the discount factor used in the financial model.
The third case is to eliminate the minimum load limit (MLL).The minimum load limit prevents RSPP from fully supplying the load.This situation requires the removal of the minimum import requirement.Such support policies were temporarily implemented through the MEMR Ministerial Order in August 2020 in response to the impact of COVID-1961.
The fourth scenario is the rework of the Network Metering Scheme (NMS).In this case, the NMS was redesigned to compensate for 100% of the output energy.The GOI has planned for this adjustment by amending Ministerial Regulation No. 49/2018 on RSPP in 202162.
The fifth scenario requires the implementation of a non-subsidized tariff (NST).Higher electricity prices may prompt customers to change the way they meet their energy needs, while generating more revenue for RSPP.In this case, the BPP value will be used as the electricity price.
This section presents the results of the irradiance potential of a mosque roof and a case study of applying the RSPP operational and financial model to a mosque in several modeling scenarios.Modeling capacities for RSPP are between 0.75 and 5.25 kWp, using 2-14 modules, respectively.The CAPEX for these systems is between $1000.7 and $1233.8/kWp.
Analysis of site conditions indicated that the solar irradiance potential of the case study site was 1,971 kWh/year.m2 or equal to 5.4 daily equivalent solar hours (ESH).This potential is realized through optimal solar panel tilt and azimuth configurations of 10° and 6°.The potential for each side of the roof is shown in Table 6.The west side roof has a higher irradiance potential due to its azimuth and tilt angles being close to optimal values.Therefore, the RSPP designs in the following sections will use the west side roof parameters.The results also show that this particular roof configuration generates 1374.7 kWh/kWp of electricity, which may represent an estimate of RSPP for mosque roofs since mosques (including case studies) are often built in a particular orientation for religious purposes.
The results show negative values ​​for all PV module numbers and types in the BAU scenario.The RSPP with a capacity of 0.75 kWp achieves the highest NPV of -$382, as shown in Figure 7.The highest annual income is $138.8 and the RSPP is 3.375 kWp.An RSPP with this capacity would produce a net load of 2600.68 kWh, then capped at a minimum load limit of 2,640 kWh, as shown in Figure 8.At higher module counts, RSPP’s annual revenue is reduced due to the bill savings limit to the minimum load limit when OPEX continues to increase.This condition further reduces NPV at a higher rate.A negative NPV means that annual bill savings from RSPP usage cannot be returned to CAPEX.
Setting a carbon price in this case can be used as additional revenue when calculating the annual revenue of the RSPP.The increase in NPV value is visible in Figure 9, but all PV module numbers and types still have negative NPV values.In this case, an RSPP with a capacity of 0.75 kWp would generate a maximum NPV of –$257, resulting in cumulative savings of 17.9 tonnes CO2e over its operational life.Net load is unaffected, and there is a reduction in revenue for the larger capacity RSPP.The widening gap between BAU and CP explains the increase in income and NPV due to carbon pricing policies.This situation means that higher RSPP capacity will benefit more from the carbon pricing scheme.However, when the minimum load limit is reached, the higher capacity RSPP does not generate additional carbon emission reductions.Therefore, the gap between BAU and CP becomes parallel.
BAU scenario modelling found that the current regulations on minimum load limits adversely affect the financial attractiveness of RSPP at higher capacity.So in this case the restriction is removed.This policy adjustment allows RSPP owners to meet their entire electricity needs directly from RSPP and export compensation.In this case, RSPP’s revenue keeps increasing as RSPP capacity increases, as shown in Figure 10.However, the NPV of all PV module configurations is still negative, and the RSPP with the highest NPV is the same as the BAU case.As shown in Figure 11, the RSPP with the highest capacity of 5.25 kWp provides 84.4% of the load for the mosque with a net present value of -$2,485.In the BAU scenario, this configuration would yield a much lower NPV of -$3573.
In this analysis, the net metering scheme was redesigned to compensate for 100% of the energy exported from the PV system to the grid.Higher outlet compensation allows RSPP with the same number of PV modules to reduce more load, as shown in Figure 12.This effect is more pronounced at lower net load levels, eg RSPP with 11 PV modules under the NMS scheme can reduce loading as much as RSPP with 14 modules under the BAU scenario.However, with the minimum load limit still in place, this situation would cause RSPP to exceed the limit with a lower RSPP capacity than the BAU scenario.Therefore, additional load reduction does not apply to RSPP when the load limit is exceeded, as shown in Figure 13.This condition also results in higher annual income and NPV.The RSPP with the highest NPV was in the same situation as the BAU, with a slight increase in NPV of -$313.
In this analysis, electricity prices are unsubsidized and taken from BPP.This situation only affects the revenue of the different RSPP capacity, while the net load is the same as the BAU.In this case, revenue and NPV will increase, as shown in Figure 14.Using RSPP can save even more on your bill due to higher electricity prices.Positive NPV was also achieved for RSPP capacities below or equal to 3.375 kWp.The RSPP with a capacity of 1.875 kWp produced the highest NPV of $144.44.
In some RSPP capacity, this situation may also reduce annual electricity bills below the subsidized electricity tariff scheme.During the operating life of the RSPP, the subsidized electricity price is between 6.27 and 7.87 US cents/kWh.Without any RSPP usage, the mosque’s annual electricity bill for the period was between $386.55 and $485.11.Meanwhile, unsubsidized electricity prices ranged from $9.64 to $12.10/kWh.Therefore, the annual electricity charges for different RSPP capacities under the NST scenario are shown in Figure 15.Despite the increase in electricity prices, the annual electricity bills for the 3 kWp and 3.375 kWp RSPP mosques are $355.86 and $319.52, respectively, lower than those in the subsidized tariff scheme.Higher capacity RSPPs also result in lower annual bills, but these systems have a negative NPV.
It should be noted that the NPV of RSPP in this case cannot be directly compared with the NPV of RSPP in the BAU scenario shown in Figure 7.A zero NPV may indicate that the RSPP is able to recoup its investment.This also means that investing in such an RSPP will incur the same cost as fully satisfying the load by importing electricity from the grid.Therefore, due to the tariff difference, the mosque will spend more money than the BAU in the NST scenario to satisfy the load.Combined, the present value of additional costs for 25 years of use due to increased electricity bills is $2,834.23.Therefore, the overall cost of meeting the load under the NST scenario is higher compared to the current subsidized tariff conditions.It is shown that RSPP can help to reduce this cost slightly, as can be seen from the slight increase in NPV for systems with lower capacity equal to 3.375 kWp.The highest NPV for the NST scenario in this analysis is -$2,689.8, as shown in Figure 16, and the RSPP is 1.875 kWp.
In this paper, we evaluate the RSPP design of a mosque and its economic impact.Despite the carbon reduction benefits, at current electricity prices and the capital cost of modules, and the regulations surrounding the adoption of RSPP, it is not financially feasible to install rooftop PV systems on mosques with negative NPV representations.- The highest NPV of $382 is achieved with a 0.75 kWp RSPP.Electricity subsidy results in less annual revenue for RSPP to recover its capital expenditures.Partial egress compensation forces the user to increase the RSPP capacity in order to obtain the same energy from the RSPP in the full egress scenario.However, due to revenue caps and an increase in OPEX as a function of RSPP capacity, minimum load restrictions prevent users from installing high-capacity RSPPs.The results of this study mirrored that of Darghouth et al.Low electricity prices and minimum load restrictions hinder the financial attractiveness of RSPP in Indonesia.This study also expands the scope of previous research to include an analysis of social sector clients and different scenarios.Indonesia’s less supportive regulatory structure for RSPP may lead to different conclusions from existing studies of SPP integration in mosques in other countries, which have documented positive results.
The results of this paper should serve policymakers to reflect current regulations on the adoption of PV in the power sector.This paper provides an insight that plans to increase the share of renewables in electricity generation to 23% by 2025 may be hampered by existing regulations.Several policy adjustments are proposed and simulated to explore their impact on the financial attractiveness of the RSPP:
Carbon pricing, export offset rework, and non-subsidized tariffs increase revenue and NPV based on RSPP capacity until the minimum load limit is reached.Prioritize the adjustment of minimum load limits to maximize the implementation of other supporting regulations.
The results show that, at the project level, the setting of non-subsidized electricity tariffs can increase the financial viability of RSPP as indicated by positive NPV and low annual electricity tariffs.However, a significant increase in the price of electricity has brought down the present value.Since the main obstacle to RSPP is capital expenditure, it is proposed to shift the subsidy from electricity tariffs to funding the deployment of RSPP.For the case study analyzed, the amount of discounted subsidies granted by the government for 25 years of use was approximately $2,834.23.The same amount of funding could fund the 2.8 kWp RSPP.According to the analysis, an RSPP with this capability could reduce the annual bill of the research mosque to a level equal to or lower than that in the subsidized tariff scheme.In addition to this, RSPP also offers opportunities to reduce carbon emissions.Overall, this approach can improve the effectiveness of government capital spending in supporting electrification programs, while achieving the goal of renewable energy integration.