Solar Roof Calculator
See how much solar you can fit on your roof and what it will generate.
About the Solar Roof Calculator
The Solar Roof Calculator gives you a clear, instant answer to a question that usually means digging through tables or guessing — enter your numbers and read the result straight away.
A correctly sized solar system is the difference between a great investment and a disappointment. This Solar Roof Calculator sizes your off-grid or hybrid solar system from your daily energy needs and the peak sun hours in your city, telling you the kW system and battery capacity required.
The calculation works backwards from what you actually consume: your daily kilowatt-hours divided by the usable sun hours gives the solar array size, and your night-time load determines the battery bank. Oversizing wastes money; undersizing leaves you on the grid — this tool finds the balance.
Peak sun hours vary across Pakistan — Quetta and the south see more than the northern cities. The calculator's sun-hours input lets you set the figure for your location, or use the default for a typical Pakistani city.
Beyond the array size, factor in losses: inverters, wiring and battery efficiency typically mean you should add a 20–25% margin to the theoretical size. The results here give you the honest engineering figure to discuss with installers, so you can compare quotes on an equal basis.
Come back to the Solar Roof Calculator whenever your numbers change; because everything runs live in your browser, you can re-run it as many times as you need at no cost.
How to size a solar system
- 1
Enter your average daily energy consumption in kilowatt-hours (from your electricity bill).
- 2
Enter the peak sun hours for your city — typically 4.5–6 in Pakistan.
- 3
Enter the battery backup capacity you need for night-time or cloudy days, if the tool asks.
- 4
Read the recommended solar array size in kW and battery capacity, updated live.
- 5
Add a 20–25% margin when discussing with installers to cover system losses.
Frequently Asked Questions
How much solar fits on a typical roof?
Each panel needs ~2.6 m² plus spacing. A 50 m² usable roof fits ~15 panels — a 8.25 kW system producing ~11,300 kWh/year in Lahore.
How many solar panels do I need for 1 kW?
Most panels in Pakistan are 550–585 W, so 1 kW of capacity needs roughly two panels. A typical Pakistani home consuming 500–800 units per month needs a 8–12 kW system.
How much does a solar system cost in Pakistan?
Prices vary with panel brand and inverter quality, but a ballpark is Rs 150,000–250,000 per kW installed in 2025. Use the size from this calculator to estimate your total before negotiating.
Do I need a battery with solar?
Only if you want backup during outages or at night. On-grid systems with net metering need no battery; hybrid systems add batteries for backup. Batteries significantly raise the upfront cost.