Solar System Size Calculator
Enter monthly or daily consumption to estimate capacity, panel count and the roof area required.
Used only if monthly is empty.
Assumptions and formulas
4 peak sun hours/day, 80% system efficiency, 550 W panels, 10 m² per kW (flat roof) or 8 m² per kW (sloped roof), 0.5% yearly output decline. Monthly generation = kW x 30 x 4 x 0.8. If you enter daily usage instead of monthly, monthly units = daily x 30. The same sun-hour assumption is used for every location; real values vary by district and season.
Disclaimer: results are illustrative estimates based on the assumptions above, not a quotation or guarantee. Actual generation depends on your site, shading, season and equipment.
How size is worked out
Monthly units are divided by what one kW generates in a month under the stated sun-hour and efficiency assumptions, then limited by your roof area if provided.
Why a site visit still matters
Shading, orientation and local weather change real output. Hilly places in particular can differ from the assumption.
Frequently asked questions
Are these results a quotation?
No. They are illustrative estimates from the stated assumptions.