Solar Energy
Solar Panel Output Calculator
Daily and annual energy from a solar array, from panel wattage and local sun hours.
daily kWh = array kWp × peak sun hours × …
Also called solar output calculator · pv generation calculator
Energy & Environment · 7 calculators
Solar Energy Calculators
Solar panel output, system size, number of panels, batteries, inverters, savings and payback — you enter local sun hours.
Solar Energy
Solar System Size Calculator
Solar array size in kWp needed to cover a given share of your electricity use.
kWp = target kWh ÷ (sun hours × 365 × der…
Also called what size solar system · kwp calculator
Solar Energy
Solar Panels Needed Calculator
How many solar panels you need for a daily energy target, and the roof space they take.
panels = daily need ÷ (panel kW × sun hou…
Also called how many solar panels do i need · number of solar panels
Solar Energy
Solar Battery Calculator
Battery storage size for a solar system, based on evening use and days of autonomy.
kWh = evening use × days ÷ DoD ÷ round-tr…
Also called solar storage size · home battery for solar
Solar Energy
Inverter Size Calculator
Inverter rating for a solar array or off-grid load, including surge headroom.
inverter W = array Wp ÷ DC:AC ratio × (1 …
Also called what size inverter do i need · inverter sizing calculator
Solar Energy
Solar Savings Calculator
Annual savings from solar, split between self-consumption and export, over 25 years.
saving = self-used × import rate + export…
Also called solar bill savings · how much will solar save
Solar Energy
Solar Payback Calculator
How long a solar installation takes to pay for itself, with the 25-year net return.
payback = install cost ÷ annual saving (w…
Also called solar roi calculator · solar break even
Key solar energy formulas
| Solar Panel Output | daily kWh = array kWp × peak sun hours × derate factor |
|---|---|
| Solar System Size | kWp = target kWh ÷ (sun hours × 365 × derate) |
| Solar Panels Needed | panels = daily need ÷ (panel kW × sun hours × derate) |
| Solar Battery | kWh = evening use × days ÷ DoD ÷ round-trip efficiency |
| Inverter Size | inverter W = array Wp ÷ DC:AC ratio × (1 + headroom) |
| Solar Savings | saving = self-used × import rate + exported × export rate |
| Solar Payback | payback = install cost ÷ annual saving (with escalation and degradation) |
Solar Energy questions
What are peak sun hours?
The number of hours per day equivalent to full 1,000 W/m² sunshine. It bundles the whole day’s irradiation into one number.