A rooftop solar power system designed for residential housing in Makassar City has demonstrated strong technical and economic feasibility, with an estimated investment payback period of around seven years. The research was conducted by Gatot Suprayogi, Jaka Windarta, and Asep Yoyo Wardaya from Universitas Diponegoro Semarang and published in 2026 in the International Journal of Education and Life Sciences (IJELS). The study analyzed the design of a 3300 Wp rooftop solar power plant installed on a house with a 15-degree roof angle in the Nusa Tamalanrea Indah Housing Complex, Makassar.
The study highlights the growing urgency of renewable energy development in Indonesia as electricity demand continues to increase alongside population growth and urban expansion. PT PLN’s customer base reached 96.2 million by 2025, with household consumers representing the largest segment. At the same time, the Indonesian government has targeted a rooftop solar power plant quota of 3.9 GW for 2024–2025 to accelerate the national clean energy transition.
Researchers explained that Indonesia’s geographical position along the equator gives the country significant solar energy potential. However, fossil-fuel-based electricity generation still dominates the national energy mix, contributing to carbon dioxide emissions and climate change. The study argues that rooftop solar systems can reduce household dependence on electricity generated from coal, diesel, and gas power plants.
The research was conducted using PVsyst software to simulate the performance of rooftop photovoltaic (PV) systems under Makassar’s climate conditions. Several technical variables were analyzed, including roof angle, solar radiation direction, rooftop area, weather conditions, PV module type, inverter configuration, and automatic control systems such as Automatic Transfer Switches (ATS).
The rooftop solar design focused on a residential house with a roof area of 90 square meters. After accounting for water storage areas and maintenance access, researchers estimated that approximately 62.3 square meters of roof space could be effectively used for solar panels, accommodating up to 24 PV modules.
The system analyzed in the study used six mono-crystalline PV modules with a total installed capacity of 3,300 Wp. Researchers selected mono-crystalline modules because they generally offer higher efficiency compared to polycrystalline panels, despite having higher market prices.
The study found that the average household electricity demand reached 15.284 kWh over 24 hours, while daytime electricity consumption averaged 8.184 kWh. Since rooftop solar systems generate energy primarily during daylight hours, the system was designed to maximize electricity production between 10:00 AM and 3:00 PM, when solar radiation is strongest.
According to the simulation results, the rooftop solar installation could generate approximately 5,541 kWh of electricity annually. About 88.7 percent of the generated electricity was directly used for household consumption, while 11.3 percent was stored in batteries. Researchers also noted that around 953 kWh of electricity remained unused because the system was configured as a self-consumption rooftop solar system that was not connected for electricity export to the PLN grid.
The study included a detailed economic analysis of the rooftop solar investment. Initial installation costs were estimated at approximately Rp30.665 million, covering PV modules, batteries, inverter systems, control equipment, installation, and maintenance expenses. Annual maintenance costs were estimated at Rp250,000, mainly for cleaning and routine maintenance.
Researchers calculated that the rooftop solar investment would produce annual savings of approximately Rp4.31 million from reduced PLN electricity consumption. Based on the simulation, the project achieved:
- Payback Period (PP): 7 years and 2 months
- Net Present Value (NPV): Rp27.95 million
- Internal Rate of Return (IRR): 8 percent
- Estimated Net Profit: Rp19.94 million
The payback period chart on page 13 shows that cumulative profit becomes positive after the eighth year of operation and continues to increase significantly over the system’s estimated 20-year lifespan.
The study also emphasized the importance of safety systems in rooftop solar installations. Researchers designed the system with Automatic Transfer Switches (ATS), Solar Charge Controllers (SCC), timers, circuit breakers, and protection systems compliant with Indonesian electrical standards such as PUIL and IEC. These systems ensure that the rooftop solar installation automatically switches between solar energy and PLN electricity when solar generation becomes insufficient.
According to Gatot Suprayogi and the Universitas Diponegoro research team, rooftop solar systems offer a practical solution for supporting Indonesia’s energy transition while reducing greenhouse gas emissions. The researchers argued that broader public adoption of rooftop solar technology could significantly lower dependence on fossil-fuel-based electricity generation.
The study also recommended stronger government support for rooftop solar adoption, including subsidy programs, revised electricity export regulations, and policies to facilitate access to solar technology in urban and remote regions. Researchers additionally emphasized the importance of developing recycling systems for used PV modules and batteries to minimize future environmental impacts.
Author Profiles
- Gatot Suprayogi – Universitas Diponegoro Semarang; bidang keahlian energi terbarukan dan desain sistem PLTS atap.
- Jaka Windarta – Universitas Diponegoro Semarang.
- Asep Yoyo Wardaya – Universitas Diponegoro Semarang.
Research Source
Suprayogi, G., Windarta, J., & Wardaya, A. Y. (2026). Design Analysis of a 3300 Wp Rooftop Solar Power Plant with a 15° Roof Angle at the Nusa Tamalanrea Indah Housing Complex in Makassar City. International Journal of Education and Life Sciences (IJELS), Vol. 4 No. 4, April 2026, pp. 419–438.
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