Solar System Sizing Calculator for Thailand Homes
The easiest way to size your solar system is to match it to your monthly electricity bill. Use our guide below or contact us for a professional assessment.
Quick Reference: System Size by Monthly Bill
| Monthly Bill (THB) | Approx. Usage (kWh) | Recommended System | Panel Count (550W) | Roof Area Needed | Est. Monthly Savings |
|---|---|---|---|---|---|
| 1,500 – 2,500 | 150–250 | 3 kW | 6 | ~18 m² | 1,200–2,000 THB |
| 2,500 – 4,000 | 250–400 | 5 kW | 10 | ~30 m² | 2,000–3,500 THB |
| 4,000 – 6,000 | 400–600 | 7 kW | 14 | ~42 m² | 3,500–5,500 THB |
| 6,000 – 9,000 | 600–900 | 10 kW | 20 | ~60 m² | 5,500–8,500 THB |
| 9,000 – 15,000 | 900–1,500 | 15 kW | 30 | ~90 m² | 8,500–14,000 THB |
| 15,000+ | 1,500+ | 20+ kW | 40+ | 120+ m² | Custom quote |
Based on 4.5–5.5 peak sun hours, 550W monocrystalline panels, and MEA/PEA electricity tariffs. Actual savings vary by shading, roof orientation, and local tariff.
How to Calculate Your Exact System Size
Follow these steps for a rough estimate, then get a professional survey for precision:
- Find your monthly kWh usage: Check your electricity bill. Divide the total kWh by 30 for daily usage.
- Estimate daily production needed: Multiply your daily kWh by 1.2 (accounts for system losses and rainy days).
- Divide by peak sun hours: Use 4.5–5.5 hours for most of Thailand. See our sunlight hours guide for regional data.
- Result = system size in kW: For example: 30 kWh/day ÷ 5 hours = 6 kW system.
Roof Space & Orientation
Ideal Roof Direction
South-facing is best in Thailand. East and west-facing roofs lose 10–15% but are still viable. North-facing is least ideal.
Roof Angle
15–20° tilt is optimal. Flat roofs work too — we use adjustable tilt mounts.
Shading Check
Trees, buildings, or water tanks casting shadows between 10am–3pm significantly reduce output. We assess this during our site survey.
Structural Load
A 5 kW system adds ~150 kg. Most concrete roofs handle this easily. We verify roof integrity before installation.
Net Metering Considerations
Thailand's net metering program (SCO 1/2561) allows you to sell excess solar energy back to the grid at ~2.20 THB/kWh. This means you can install a slightly larger system to maximize long-term savings, even if you don't use all the energy immediately.
We help you register for net metering and handle all MEA/PEA paperwork as part of our professional solar installation service.
Related Guides
Get a Tailored System Recommendation
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Get a Free QuoteBased in Koh Chang, serving all of Thailand since 2016.