Solar panel output calculator
How much power do your solar panels actually produce? Enter panel wattage, count and sun hours — get daily, monthly and annual kWh.
Quick answer: Watts × peak sun hours × 0.86 (losses) ÷ 1000 = kWh/day. Ten 410 W panels at 4.2 sun hours make about 14.8 kWh per day — roughly 444 kWh a month.
Your array
Ballpark, not gospel. Shading, panel orientation, tilt and local weather shift real output ±20%. Use this for planning; an installer's shade analysis gives the final number.
Daily output by system size (4.2 sun hours, 14% losses)
| System size | Panels (410 W) | kWh / day | kWh / month |
|---|---|---|---|
| 1 kW | 3 | 3.6 | 108 |
| 3 kW | 8 | 10.8 | 325 |
| 5 kW | 13 | 18.1 | 542 |
| 10 kW | 25 | 36.1 | 1,083 |
Scale these by your sun hours: Pakistan (5.4 h) makes ~29% more than this table; the UK (2.9 h) makes ~31% less. Switch the country preset above to see it live.
Questions people actually ask
Straight answers, no fluff. Then run your own numbers above.
How much power does a 400W solar panel produce per day?
About 1.4–1.6 kWh per day in average conditions: 400 W × 4.2 peak sun hours × 0.86 (14% system losses) ≈ 1.44 kWh. In strong sun (5.5 hours) the same panel makes ~1.9 kWh.
How do you calculate solar panel output?
Multiply panel wattage by peak sun hours, then subtract system losses (~14%): output = watts × sun hours × 0.86 / 1000 kWh. Ten 410 W panels at 4.2 sun hours give about 14.8 kWh/day.
What are peak sun hours?
The equivalent hours of full 1000 W/m² sunshine per day — not daylight hours. The US averages ~4.2, the UK ~2.9, India ~5.3, Pakistan ~5.4. Your location's number drives everything.
Why is real output lower than the panel wattage?
Panels are rated in lab conditions. In the field, heat, dust, wiring, inverter conversion and shading eat ~14% — a 410 W panel rarely delivers 410 W. The calculator applies this loss automatically.
How much does a 5 kW system produce per day?
About 18 kWh/day at 4.2 peak sun hours (5 × 4.2 × 0.86). In Pakistan or India at 5.4 sun hours the same system makes ~23 kWh/day; in the UK at 2.9 hours, ~12.5 kWh/day.
Do solar panels produce power on cloudy days?
Yes, but much less — heavy cloud typically cuts output to 10–25% of clear-sky production. That is why off-grid designs add days of battery autonomy instead of more panels.
What is solar capacity factor?
Actual annual output divided by the theoretical maximum (running at full rating 24/7). Residential solar runs ~13–20% depending on location — the calculator shows yours.
How many kWh per month will 10 panels produce?
Ten 410 W panels (4.1 kW) at 4.2 sun hours make ~14.8 kWh/day, or ~444 kWh/month. Change the country preset above to see your location's number.
Turning output into savings? The solar ROI calculator converts kWh into payback years. Sizing storage for that energy? The battery size calculator tells you the bank you need, and the system calculator matches the inverter.