Rooftop solar calculator
How much solar does your roof need?
Enter your bill and roof – see system size, panels, generation, savings, PM Surya Ghar subsidy and payback in seconds.
How we calculate
Transparent assumptions
Your requirement
From your bill (bill ÷ unit rate), your monthly units, or your usable roof area.
Plant size
Daily units ÷ solar generation per kWp in your state (3.4–4.7 units/kWp/day), rounded to whole panels of 585–700 Wp – or the best-fitting wattage.
Roof area
About 70 sq ft of shadow-free roof per kWp.
Subsidy & payback
PM Surya Ghar (DCR panels): ₹30,000/kW for the first 2 kW and ₹18,000 for the 3rd kW – max ₹78,000 for homes, 10% more in special-category states; ₹18,000/kW for housing societies. Payback = net cost ÷ yearly saving.
All results are indicative. Actual generation depends on orientation, shading and weather; costs and subsidy depend on your DISCOM and current government rules. We confirm everything after a free site survey.
Authorised dealing
Panel & inverter brands we deal in
Solar PV modules
MNRE ALMM-listed, BIS & IEC 61215 / 61730 certified modules – TOPCon bifacial from 585 Wp to 700 Wp.
Ask us for the current brand list and best price.
Solar inverters
BIS & IEC 62109 / 61727 / 62116 certified on-grid, off-grid and hybrid inverters.
Ask us for the current brand list and best price.
Talk to an engineer
Get your solar requirement solved today
Share your result from any of our tools – we reply with a detailed quotation and site-survey date.