Solar Panel Output Calculator — measure your solar panel output impact. Evidence-based formula with reduction tips.
Annual generation (kWh) = System size (kWp) × Solar yield (kWh/kWp) × System efficiency factor
Annual bill saving = Self-consumed kWh × Electricity unit rate
Export earnings = Exported kWh × Export/feed-in rate
Simple payback (years) = Installation cost ÷ (Annual saving + Export earnings)
Worked example: 4 kWp system, 1,100 kWh/kWp solar yield, 80% efficiency. Annual generation = 4 × 1,100 × 0.80 = 3,520 kWh. 50% self-consumption: 1,760 kWh saved at 0.28/kWh = 493/year. Export 1,760 kWh at 0.10 = 176/year. Total annual benefit = 669. System cost 7,000. Payback = 7,000 ÷ 669 = 10.5 years.