Last updated: 21 June 2026
Solar Panel Roof Area Calculator
Estimate usable roof area at a conservative 100 sq ft per kW and compare it with the capacity your electricity use suggests.
Independent calculator — not a government website.
Central subsidy slabs
For eligible residential households under PM Surya Ghar.
Up to 1 kW
₹30,000
Up to 2 kW
₹60,000
3 kW or higher
₹78,000
maximum
No extra central subsidy beyond 3 kW.
Default roof area assumption
The calculator uses 100 sq ft per kW. This is a planning allowance for modules, spacing, access and a typical mounting layout—not a panel-dimension guarantee.
- 1 kW: about 100 sq ft
- 2 kW: about 200 sq ft
- 3 kW: about 300 sq ft
- 5 kW: about 500 sq ft
Usable area is smaller than total terrace area
Keep clear of parapet shade, water tanks, stair rooms, vents and maintenance paths. A site survey should check shade through the day and across seasons rather than measuring only the terrace outline.
Structure and layout need professional review
The calculator does not assess structural capacity, wind load, waterproofing or mounting design. Ask the installer to document the layout, access path, drainage, earthing and structural approach.
Frequently asked questions
Clear answers, with the important caveats left in.
How much roof area is needed for a 3 kW solar system?
The calculator estimates about 300 sq ft of usable, largely shadow-free roof area. Actual module efficiency and layout can change the requirement.
Can panels be installed around a water tank?
Sometimes, but tank and structure shade, access and piping must be considered. A proper shade study and layout are needed.
Does this calculator check roof strength?
No. It estimates area only. Structural suitability and mounting design require a qualified site assessment.
How accurate is this calculator?
It is a planning estimate based on the values you enter, a state-level solar-yield assumption and the published central subsidy slabs. Shade, roof direction, equipment performance, local tariff design and approval rules can materially change the real outcome.
Is this website official?
No. This is an independent calculator and is not affiliated with the Government of India, MNRE, PM Surya Ghar or any DISCOM. Verify eligibility and subsidy amounts on the official portal and with your DISCOM.
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