Roof area to kW calculator
Measure your roof, and see how much solar it physically fits and what that would generate.
Your details
Leave room for the water tank, staircase head, walkways and parapet setbacks. 75% is typical for an Indian RCC roof.
Shading costs you generation, not roof space. The panels still fit.
Your estimate
Solar your roof can fitEstimated
7.9 – 10.0 kW
On about 750 sq ft of usable roof, once walkways and setbacks are left clear.
- Panels
- 15 – 20
- Generation
- 1,018 – 1,470 units / month
- Over a year
- 12,391 – 17,885 units
Assuming 500 W modules, the size currently installed.
More than a typical household uses — this is shop, showroom or small-factory scale.
Summer months run well above this, monsoon months below it.
This is an estimate, not a quote.
This is an estimated range based on average conditions in your area. Your actual numbers depend on site-specific factors we verify before quoting.
Rates last verified 2026-08-06
Get the number we stand behind
Origian Power stands behind the number our engineer gives you after a free site visit — not the number above.
- The true usable area once obstructions are measured, not estimated
- Which way the roof faces, which changes generation more than area does
- Shading through the day, which only a site visit can see
Roof area is a ceiling, not a target
This tool answers one question: what will physically fit. That is a useful ceiling to know before anyone quotes you, because a proposal for more capacity than your roof carries is a proposal that will change on survey.
It is not the same question as what you should install. Sizing follows consumption: a system that generates far more than you use exports the surplus, and export is credited at the net-metering rate rather than the retail rate you avoid. The savings calculator sizes against your bill instead.
Questions about this estimate
How much roof does one kilowatt of solar need?
Roughly 80 to 100 square feet per kilowatt for standard modules, once you allow the gaps between rows that stop the panels shading each other. Higher-wattage modules need slightly less area for the same capacity.
Why does the calculator ask for a usable share?
Because almost no roof is fully available. Water tanks, the staircase head, walkways and parapet setbacks all take space, and panels cannot sit hard against a parapet without shading. Seventy-five per cent is a reasonable starting figure for an Indian RCC roof.
Does shading reduce how many panels fit?
No. Shading costs you generation, not roof space: the panels still fit, they just produce less. That is why the shading input changes the generation figures here and not the capacity.
Should I install the largest system my roof allows?
Not usually. The right size follows your consumption, not your roof. A system much larger than your usage exports more than it offsets, and export is credited below the retail rate. Use the savings calculator to size against your bill.
Ready to find out what solar would do for your bill?
Book a free site survey. We assess your roof, your consumption and your connection, then tell you what is actually worth installing.