How Many Solar Panels Do I Need? Calculate From Your Bill

Panel count depends on the system size you need, which comes from your electricity bill and daytime usage. This guide shows a simple calculation with a reference table.

Size the System From Your Bill

Check your monthly usage (kWh) on the bill. Roughly: a 1kW system produces ~120-130 units/month in Thailand. If you use 600 units/month with full daytime use → you need ~5kW. If you use a lot at night, an On-Grid system may be less worthwhile — consider Hybrid + battery.

How Many kW = How Many Panels?

Panel count = system power ÷ per-panel power. With 450W panels: 3kW ≈ 7 panels, 5kW ≈ 11-12 panels, 10kW ≈ 22-24 panels. With high-power 600W+ panels (e.g. Aiko 670W): 5kW ≈ 8 panels, 10kW ≈ 15 panels — saving roof space.

Is Your Roof Big Enough?

Each panel takes ~2 square meters. A 5kW system needs ~25-30 sqm, 10kW needs ~50-60 sqm. For limited roofs, choose high-efficiency panels (Aiko ABC) for more power in less space. QES engineers measure and design the layout free.

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Frequently Asked Questions

How many panels for 5kW solar?

About 11-12 panels (450W) or 8 panels (high-power 600-670W).

How many panels to power a whole house?

Depends on your bill — a typical home uses 500-700 units/month, needing a 4-6kW system = 9-15 panels.

How many panels fit a small roof?

Depends on sun-exposed area — each panel takes ~2 sqm. For limited space, choose high-power panels for more kW in fewer panels.