The right system size comes from your electricity consumption, not from a fixed package. This guide shows you how to estimate it yourself in a few minutes. For an instant estimate, try our solar system calculator.
Start with your bill
Your electricity bill shows the units (kWh) you used each month, and usually a 12-month history. Add up the last 12 months and divide by 12 to get your average monthly units. Summer months matter most for Pakistani homes because air-conditioning drives consumption. If your goal is to cover peak months, size towards those.
How much does 1 kW of solar produce?
In Punjab, a well-designed, clean, unshaded system typically produces around 120–130 units per kW per month on average across the year, roughly 1,400–1,550 units per kW annually. Output is higher in spring and summer and lower during foggy, smoggy winter weeks.
So a quick rule of thumb is:
System size (kW) ≈ average monthly units ÷ 125
| Monthly units | Suggested size | Panels (≈580 W) |
|---|---|---|
| 300 | 3 kW | 5–6 |
| 600 | 5 kW | 9 |
| 1,000 | 8–10 kW | 14–17 |
| 1,500 | 12 kW | 21 |
| 2,500 | 20 kW | 35 |
How many panels for 3, 5 and 10 kW?
Divide the system size in watts by the panel wattage. Modern Tier-1 panels in Pakistan are typically 540–610 W. A 3 kW system needs about 5–6 panels, a 5 kW system needs 8–10 panels, and a 10 kW system needs about 17–18 panels. Higher-wattage panels mean fewer modules and less roof space for the same capacity. Our panel buying guide explains the options.
How many panels for a 1-ton or 1.5-ton AC?
A modern inverter AC draws roughly 0.8–1.2 kW (1 ton) or 1.2–1.8 kW (1.5 ton) while running, depending on its efficiency and the outside temperature. Allowing for real-world losses in Pakistan’s heat:
- 1-ton AC: around 4–6 panels
- 1.5-ton AC: around 6–8 panels
- 2-ton AC: around 8–10 panels
These figures are for running the AC during daylight. Night-time cooling needs batteries (a hybrid system) or the grid.
How much roof space do I need?
A 580 W panel measures roughly 2.3 m × 1.1 m. On a flat roof with tilted rows you need space between rows to avoid self-shading, so plan for roughly 80–100 sq ft of shade-free roof per kW. Elevated structures can make better use of rooftops with water tanks or obstructions, which is common in Pakistani homes.
Rules of thumb get you close, but shading, roof layout and your load profile decide the final design. Our survey & design service models your exact site in 3D and PVsyst.
