Solar system size calculator
Size a solar system from your monthly units: kW, number of panels and payback.
Estimate for information only — not financial, tax, legal or medical advice.
How it's calculated
kW = (monthly kWh ÷ 30) ÷ (peak sun hours × (1 − losses)). Panels = ceil(kW × 1000 ÷ panel W). Savings = units offset × tariff.
- Peak sun hours vary by city and season (Pakistan typically ~4.5–6)
- Net-metering buyback rates are not modelled
- Assumes full self-consumption
Version 1.0 · exact decimal maths · inputs are not stored.
Questions
What are peak sun hours?
The equivalent number of hours per day of full-strength sunlight. Most of Pakistan averages about 4.5–6, lower in winter and in northern areas.
Why add system losses?
Heat, dust, wiring and inverter losses mean panels deliver less than their rating. 15–25% is a common planning allowance.
Does this include net metering?
No. It assumes you use all the solar power yourself. Net-metering buyback rates and rules change, so ask your installer and DISCO.