Is Solar Worth It in Punjab With 300 Free Units?

Punjab gives homes 300 units of electricity a month free (600 on a two-month bill). It is the single biggest thing that decides whether rooftop solar is worth buying here, and most solar advertising ignores it.

The short answer

Look at the jump between 300 and 305 units. That is not a typo. And notice the payback column: it gets shorter as usage rises within the same 3 kW system, not longer.

Why one unit over the line costs so much

For general-category homes, the free units are all or nothing. Stay at or under 300 units a month and you pay nothing: no energy charges, no fixed charges, no meter rent, no duty. Go one unit over and PSPCL charges energy on every unit you used, from the first, plus fixed charges and duty.

So a home at 320 units is not paying for 20 units. It is paying for 320.

(SC, BC, non-SC BPL and Freedom Fighter households are treated differently: they pay only for the units above 300, plus fixed charges. Their cliff is smaller, but the same logic applies.)

Why payback improves as you approach 600 units, not 301

RSK’s smallest on-grid system is 3 kW. For any general-category home from just over 300 units up to roughly 550 to 600 units a month, that same 3 kW system is what gets recommended and it is priced the same regardless of exactly how far over the line you are.

Take two homes with the same 3 kW system, at the same net price. One uses 305 units a month and pays about ₹1,880; solar saves it about ₹22,500 a year, paying back in roughly 4.5 – 5.3 years. The other uses 450 units and pays about ₹3,030; the same system saves it about ₹36,400 a year, paying back in roughly 2.8 – 3.3 years. Same cost, bigger bill avoided, faster payback.

So the honest version of “solar pays back fastest just over the line” is: it pays back well anywhere from just over 300 units to around 600, and it pays back fastest nearer the top of that range, not the bottom. Past about 600 units the recommended system steps up in size and the price rises with it, so payback does not keep improving forever.

If your use is only just over 300 — say 305 to 350 units — solar still clears the bill and still pays back in a reasonable time (see the table above), but you are effectively buying more capacity than you strictly need, because 3 kW is where our on-grid range starts. If a smaller system would suit you better, off-grid is available from 1 kW, without the subsidy; see on-grid vs off-grid vs hybrid.

Under the line: when solar still makes sense

• Your use is about to rise. A new air conditioner, an EV, an extension or a bigger family can push you over 300 units, and then every unit is charged.
• Power cuts are a real cost. A hybrid system with batteries keeps essentials running, and still receives the same PM Surya Ghar subsidy as on-grid. The return here is backup, not bill savings — under the free-units line there is no bill left to save on.
• You sit close to the line. If some months cross 300, those months bring a full bill. Look at your hottest two-month bill, not your average.

One thing to confirm

All of this assumes PSPCL applies the 300 free units to your net units after solar, which is how net metering bills are normally worked out. We check it against real post-solar bills for your connection before quoting.

Check your own bill

The calculator does this for your figures: it tells you if you are under the line, and if you are over it, the smallest system that takes your bill to zero.