Rooftop area calculator
Find out how much solar your terrace can carry before anyone climbs up there. Enter the roof size, tell us how much of it is free of shade, water tanks and stair cabins, and get the maximum kW, panel count and monthly units.
How it works
- Enter length and width (or the total area) in feet or metres. Metres are converted at 1 m² = 10.764 sq ft.
- The usable percentage removes space lost to shade, tanks, stair cabins, parapets and walkways.
- Usable area ÷ 70 sq ft per kW gives the maximum capacity.
- Capacity is divided into whole 550 W panels (rounded down), giving the installable system size.
- Monthly units = installable kW × 126. Send the size straight to the savings calculator to see cost and subsidy.
Assumptions
- About 70 sq ft of shadow-free roof per kW, including spacing for access and maintenance.
- 550 W panels; panel count is rounded down to whole panels.
- Average generation of 126 units (kWh) per kW per month (1,512 units per kW per year).
- Electricity valued at ₹8.5 per unit.
- Roof strength, structure height and DISCOM sanctioned load can limit capacity further; these are checked on site.
- Final size, cost and eligibility are confirmed only after a free UVR site survey and DISCOM approval.
Frequently asked questions
How much roof space does 1 kW of solar need?
UVR plans around 70 sq ft of shadow-free roof for every 1 kW. That covers the panels plus walking and maintenance gaps between rows. A 3 kW home system therefore needs roughly 210 sq ft. Elevated structures, panel wattage and roof shape can change this, so the engineer confirms the exact layout during the site survey.
What should I set the usable roof percentage to?
Exclude anything that blocks or shades the panels: water tanks, stair cabins, parapet walls, lift rooms, dish antennas, and shade from nearby trees or buildings. If your terrace is open with few obstructions, 75–85% is a reasonable starting guess. A crowded terrace may have only half its area usable. The site survey measures this properly.
Why is the panel count rounded down?
Panels come in fixed sizes, so a roof that fits 7.6 panels can only hold 7. We divide the usable capacity by the 550 W panel size, round down, and show the actual system size those whole panels make. Your final design may use a different wattage depending on the roof layout and the modules available.
Can I use this for a sloped or sheet roof?
Yes, as a first estimate. Measure only the roof faces that get direct sun for most of the day and enter that as the roof size. Sheet and sloped roofs need a different mounting structure, so the survey team checks load-bearing capacity, fixing points and safe access before confirming how much capacity can be installed.