Your inputs
Editable example valuesYour estimate
Live calculationNo location or tariff is detected automatically. All results use the values you enter.
What is this tool used for?
Use this tool to estimate the solar array capacity and number of panels needed to cover a daily energy target. It is a starting point for comparing panel wattages and available installation space.
How to use this calculator
Enter daily electricity demand in kWh, design peak sun hours, total energy losses and the watt rating of one panel. Peak sun hours represent equivalent full-strength sunshine, not the number of daylight hours.
Understanding your results
Required kWp is the estimated array rating. Panel count is rounded up to a whole panel, and the estimated yield uses that rounded array. Check roof space and inverter input limits separately.
Common questions
Can I use this solar panels calculator for different panel sizes?
Yes. Enter the rated watts of one panel to compare panel counts for the same daily energy target. This solar size calculator sizes an array by energy demand; it does not check roof fit, module dimensions or electrical string compatibility.
How this is calculated
Before you use the result
Peak sun hours are equivalent full-sun hours, not daylight hours. Use a location- and season-appropriate value. Losses should reflect temperature, shading, wiring, conversion and any battery cycling. This energy balance does not guarantee uninterrupted off-grid supply.
Why are panels rounded up?
You buy whole modules; the installed array may exceed the calculated minimum. Check inverter PV capacity and string limits.