How rooftop solar works, how many kWp you need, how much it can cut your PLN bill, and the steps to install it at a home, villa, or business in Bali.
The electricity bill for a villa running AC and a pool pump all day, or a shop or office with lights on from the morning, is often one of the biggest fixed costs. In Bali, sunshine is available almost all year — and a roof that until now only kept the rain out can also generate electricity. That's the basic idea of rooftop solar (known in Indonesia as PLTS atap).
Solar panels turn sunlight into direct current (DC). The inverter converts it into 230 V alternating current (AC), the same as PLN electricity, and feeds it to the equipment in the building. With a hybrid system, surplus daytime energy is stored in a LiFePO4 battery for use in the evening and at night.
While the panels are producing, equipment uses solar energy first; any shortfall is automatically covered by PLN or the battery. Users don't need to flip any switch.
Solar system size is expressed in kWp (kilowatt-peak). In Bali, 1 kWp generally produces about 4–4.5 kWh per day after system losses, depending on location, roof orientation, and shading. The simple formula:
| Profile (illustrative) | Bill/month | Daytime share | Estimated capacity |
|---|---|---|---|
| Home 2,200 VA | Rp800k | 35% | ±1.5–2 kWp |
| 3-bedroom villa 7,700 VA | Rp2.5m | 50% | ±5–6 kWp |
| Shop / office 11 kVA | Rp3m | 70% | ±10–11 kWp |
The figures above are illustrations only. You can calculate a more accurate result with the Balieka Solar Calculator, which uses solar irradiance data for your location on the map.
Since Minister of Energy and Mineral Resources (MEMR) Regulation No. 2 of 2024 on Rooftop Solar came into force, surplus electricity flowing into the PLN grid no longer counts as a reduction in your bill. Installed capacity also follows quotas set per electricity system, and applications are submitted through official PLN channels.
The consequence is simple: design solar for self-consumption. A system that is too large relative to daytime use simply wastes energy. If most of your consumption happens at night, consider a hybrid system with a battery.
Installed prices vary by brand, roof type, and installation complexity. As a rough guide to 2026 market ranges, on-grid systems cost in the order of a dozen-plus million rupiah per kWp, while hybrid systems cost more because of the hybrid inverter and battery. Savings are calculated from the solar kWh actually used × your PLN tariff.
For businesses with high daytime use (shops, offices, restaurants), payback is usually faster than for homes whose main use is at night. Our calculator shows estimated cost, monthly savings, 25-year cash flow, and the payback point — with assumptions you can change.
Panel prices keep falling, N-type panel efficiency is now commonly above 21%, and LiFePO4 batteries are increasingly affordable. In future, solar will be increasingly connected to building management systems, electric vehicle charging, and data-based monitoring — a topic we also cover in our article on IoT & smart buildings.
Yes, but less. That's why calculations use monthly averages from satellite data, including the rainy-season months.
A standard on-grid system shuts down for the safety of grid workers. To keep essential loads running, use a hybrid inverter with a battery.
Quality panels generally carry a 25–30 year performance warranty with output declining about 0.4–0.5% per year; the inverter usually needs replacing once in that period.
Modern panels weigh about 12–15 kg/m² including the frame. A technical survey is still needed to confirm the structure and roof covering type.
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