How Many Solar Panels Do I Need? (Pakistan)
· 6 min read
Size a home solar system from your electricity bill, understand peak sun hours and efficiency, and estimate payback.
Start with your units
Look at the units on your last 12 bills. Summer months will be much higher than winter. Sizing for the yearly average is common for on-grid systems; sizing for summer covers more but costs more.
Peak sun hours and efficiency
Peak sun hours describe how much solar energy reaches your roof per day. Much of Pakistan averages roughly 5–6 hours across the year.
Real systems lose some energy to heat, dust, wiring and the inverter. An overall efficiency of around 75–85% is a reasonable planning figure.
The calculation
System size (kW) = daily units ÷ (sun hours × efficiency). For 500 units a month: 16.7 ÷ (5.5 × 0.8) ≈ 3.8 kW, or seven 585 W panels.
Before you buy
- Get a site survey for shading and roof strength.
- Check current net-metering/net-billing rules with your DISCO — they have changed.
- Decide whether you need batteries for load-shedding backup.
- Compare warranties on panels (performance) and inverters.