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View offerAffiliate link — we may earn a commission at no extra cost to you.Estimate daily solar generation from array capacity, peak sun hours, and a performance ratio.
The performance ratio should account for temperature, inverter, wiring, shading, soiling, orientation, and other system losses.
Estimate daily solar generation from array capacity, peak sun hours, and a performance ratio.
This calculator estimates how much electricity a solar system produces on an average day:
Daily energy (kWh) = system size (kW) × peak sun hours × performance ratio
Output varies with the seasons, so expect more in summer and less in winter. That's why annual averages are the best basis for comparing systems.
Annual averages vary by location and panel orientation. Across Australian capital cities they range from roughly 4 hours a day in the south to 5.5 or more in the north and west. Check the Bureau of Meteorology's solar exposure data, or an installer's estimate for your exact roof.
To cover a household using 20 kWh/day with 4.5 peak sun hours and 0.8 performance: 20 ÷ (4.5 × 0.8) ≈ 5.6 kW. How much you actually save depends on how much you use during the day versus export, so a battery or shifting usage to the daytime helps.
Roughly 22–30 kWh per day on average in most Australian cities, or about 8,000–10,000 kWh a year.
0.75–0.85 for most well-installed residential systems.
Yes, but at a fraction of their output, often 10–30%, depending on cloud thickness.