Solar Loan Calculator (with PM Surya Ghar Subsidy)

Why a solar loan is not like other loans

Every other loan on this site takes money out of your pocket every month and gives you nothing back until it is repaid. A rooftop solar loan is different: the asset starts producing the thing you were already buying. The EMI is real, but so is the bill that stops arriving, and the only number worth looking at is the difference between them.

On the default figures — a 3 kW system at ₹60,000 per kW, financed over five years at 10.5% — the EMI is about ₹2,192 a month while the system displaces roughly ₹2,918 of electricity. The system is cash-positive from the first month, before the loan is anywhere near repaid. That is unusual, and it is the whole case for financing solar rather than waiting to save up for it.

The subsidy, and the cap that catches people out

The PM Surya Ghar Muft Bijli Yojana pays a central subsidy on residential rooftop systems:

• 1 kW → ₹30,000
• 2 kW → ₹60,000
• 3 kW and above → ₹78,000, and no more

The structure is ₹30,000 per kW for the first two kilowatts, ₹18,000 for the third, and nothing beyond. The cap is absolute. A 6 kW system receives the same ₹78,000 as a 3 kW one — so the second half of that system is financed entirely by you, at full price. Run the numbers at 3 kW and at 6 kW in the calculator above and watch the loan amount nearly triple while the subsidy does not move.

This is why 3 kW is the sweet spot for most households: it is the largest system that is fully subsidy-efficient. Going bigger is a reasonable decision if your consumption genuinely warrants it, but it should be a deliberate one, not an upsell you accepted without seeing this table.

One timing detail that matters for cash flow: the subsidy is credited after installation and DISCOM inspection, typically some weeks later. You — or your lender — fund the full system cost first. The subsidy reduces what you ultimately owe, not what you must arrange on day one.

What drives the payback period

Payback is the net cost divided by the monthly saving, and the saving depends on two things you should enter honestly rather than optimistically:

• Generation. The default of 4 units per kW per day is a reasonable all-India annual average. Rajasthan and Gujarat run higher; the eastern and north-eastern states, and anywhere with heavy monsoon cloud or shading, run lower. A dusty, partly shaded roof can lose 10–20% against a clean, clear one.
• Your tariff. This is the single biggest lever, and it is the one most often understated. Indian domestic tariffs are usually slab-based — the last units you consume cost far more than the first. Solar displaces your most expensive units first, so the right number to enter is your marginal rate, not your total bill divided by total units.

What this calculator does not model

Deliberately kept out, because including them would imply a precision that is not available:

• Net-metering rules and export tariffs, which vary by state and are usually well below the rate you pay for import. Surplus you export is generally worth less than surplus you consume.
• Panel degradation, typically around 0.5% a year, so year-25 output is roughly 85–90% of year one.
• Inverter replacement, usually needed once in a 25-year life.
• Tariff inflation, which works strongly in your favour — the bill you avoid grows every year while the EMI does not. Leaving it out makes the 25-year figure conservative.

The 25-year net gain in the results is therefore a rough directional figure, not a forecast. The near-term numbers — EMI, monthly saving, net outgo — are the ones to lean on.