Enter your monthly electricity bill to see how long rooftop solar takes to pay for itself in Thailand. The calculator sizes a system to match your usage, estimates year-by-year savings using current MEA tariff rates, and shows your 25-year return — with or without battery storage.
The calculator converts your monthly electricity bill into estimated kilowatt-hour usage using a piecewise model based on MEA's 2026 progressive tariff structure. Higher bills don't scale linearly — a ฿3,000 bill uses proportionally more electricity per baht than a ฿800 bill because of Thailand's tiered pricing.
Based on your usage, the tool selects one of three standard residential system sizes: 3 kW, 5 kW, or 10 kW. Each size is matched with current 2026 installed costs from Thai solar providers. If you enable battery storage, the system is paired with a proportionally sized battery (5–14 kWh) that increases self-consumption from roughly 70% to 90%.
Savings are calculated year by year over a 25-year panel lifespan. Each year accounts for 0.5% panel degradation and a 3% electricity rate increase — reflecting Thailand's historical tariff trend. The break-even point is where your cumulative savings equal the total system cost.
Break-even period is the year your cumulative electricity savings equal what you paid for the system. After that point, every baht saved is pure return on your investment. Most Thai households see break-even between 5 and 8 years without a battery.
25-year net savings is your total cumulative savings minus the system cost over the full panel warranty period. This number grows significantly over time because electricity rates compound at ~3% annually while your solar production cost is fixed at installation.
Battery storage extends your break-even period by 1–3 years because of the added upfront cost, but it increases the share of solar energy you use directly (self-consumption) from about 70% to 90%. This means less energy exported at the lower ฿2.20/kWh buyback rate and more used at the full ฿4.22/kWh retail rate — which improves long-term returns.
| Parameter | Value | Source |
|---|---|---|
| Solar production | 1,350 kWh/kWp/year | Thailand average irradiance |
| Self-use electricity rate | ฿4.22/kWh | MEA tier 151–400 kWh |
| Export (buyback) rate | ฿2.20/kWh | MEA net metering program |
| Self-consumption (no battery) | 70% | Industry average, daytime use |
| Self-consumption (with battery) | 90% | Industry average, stored + daytime |
| Annual electricity rate increase | 3% | Thailand 10-year historical average |
| Annual panel degradation | 0.5% | NREL median for mono/poly panels |
It provides a conservative estimate based on published tariff data and industry-standard assumptions. Actual results vary with roof orientation, shading, local installer pricing, and your specific usage pattern. For a precise quote, get a site assessment from a licensed Thai solar installer.
No. Thailand's Board of Investment (BOI) and Revenue Department offer tax incentives for solar installations, which would shorten your actual payback period. Check the BOI website for current eligibility and rates.
The calculator uses MEA's current buyback rate of ฿2.20/kWh for exported surplus energy. This rate applies under Thailand's residential solar buyback program managed by MEA (Bangkok metro) and PEA (provincial areas). You need to register with your utility to receive export credits.
Battery storage makes financial sense if you use most of your electricity in the evening or want backup power during outages. Without a battery, you export surplus daytime solar at ฿2.20/kWh instead of using it at ฿4.22/kWh. The battery captures that difference — but the upfront cost means a longer payback. Run the calculator both ways to compare.
For a deeper look at solar economics, system sizing, and real-world performance data in Thailand, read our complete solar energy guides.