What would solar do to your bill?
Put in what you pay each month. You’ll get an indicative system size, the units it should generate, and the subsidy you qualify for.
Take it from a recent bill. An average across the year is better than one summer month.
Printed on your bill. It differs between Kerala and Karnataka, and between slabs.
How this calculation works
So you can check it rather than trust it.
Units from your bill. We divide your monthly bill by your average tariff to get monthly units. Your tariff is on your bill, and it differs between Kerala and Karnataka and between slabs.
System size. As a planning figure, one kilowatt generates roughly four units a day in Kerala and Karnataka, so about 120 units a month. Divide your monthly units by 120 and you have an approximate size in kW.
Roof area. Allow 70 to 90 square feet of unshaded roof per kilowatt. Shading matters more than total area, so a small clear roof beats a large obstructed one.
Subsidy. ₹30,000 at 1 kW, ₹60,000 at 2 kW, ₹78,000 at 3 kW and above, for residential systems under PM Surya Ghar. ₹78,000 is the ceiling, so a bigger system does not attract more.
This is an estimate, and it’s deliberately labelled as one. Real output depends on your roof angle, orientation, shading, local weather and the equipment chosen. A free site survey replaces every assumption above with a measurement. TODO: set your installed price per kW in the calculator shortcode so it can show cost and payback
Get the real number instead
The calculator uses averages. A survey uses your roof. It’s free, and it takes about an hour on site or twenty minutes on a video call.