What is it?
The Solar Panel Calculator suggests the size of a rooftop solar system for your electricity use. It shows the system size, number of panels, roof space, approximate cost, yearly savings and how many years it takes to pay back.
Who is it for?
Homeowners and shopkeepers thinking about rooftop solar, especially under the PM Surya Ghar scheme.
How to use it
- Enter Electricity used a month in units (kWh): average your last 12 bills, as summer and winter differ.
- Enter the Peak sun hours a day: about 4–5.5 in most of India, 3–4 in northern Europe, 5–6 in deserts.
- Enter the Panel size (watts), the Electricity price per unit and the Installed cost per kW from a local quote.
Assumptions
It assumes 80% overall efficiency (heat, dust, wiring and inverter losses). Clean panels regularly; dust can cut output noticeably.
India: subsidy and net metering
- In India the PM Surya Ghar scheme gives a subsidy on home rooftop systems up to 3 kW; check pmsuryaghar.gov.in. Apply through the portal with a registered vendor.
- Net metering lets you export extra power to the grid; rules and rates depend on your state’s electricity board.
Roof space
About 80–100 sq ft of shadow-free roof per kW. Keep panels facing south in India, tilted roughly at your latitude.
Errors and how to fix them
- “Enter sun hours (more than 0)”: use 4–5.5 for most of India.
Open the tool: Solar Panel Calculator
Still stuck?
Contact support. Tell us which tool or page you were using, what you tapped, what you saw, and your phone or computer and browser (for example: Android phone, Chrome). We reply by email.
Questions, or an error not listed here?
Tell us in the comments: what you were doing, the exact message you saw, and your device and browser. We read every comment and add new fixes to this article.