Benefits
Solar is worth more than the rate on your bill
KSEB does not charge one price for electricity. It charges more for every unit as you use more, and past 250 units a month it reprices your whole month at a single higher rate. Solar takes your last units off first, and your last units are your dearest ones. This page works that through on the real tariff, with the same model that runs our calculator.
How KSEB charges a home
The domestic tariff has two halves and they behave in opposite ways. Below 250 units a month it is telescopic: each band is charged at its own rate, so your first 50 units cost ₹3.35 each however much you go on to use. Above 250 units the tariff turns non-telescopic and one rate applies to every unit of the month.
Up to 250 units a month
Telescopic. Each band is charged at its own rate.
| Units in the month | Rate for those units |
|---|---|
| 1 to 50 | ₹3.35 |
| 51 to 100 | ₹4.25 |
| 101 to 150 | ₹5.35 |
| 151 to 200 | ₹7.20 |
| 201 to 250 | ₹8.50 |
Above 250 units a month
Non-telescopic. One rate is charged on every unit you used.
| Units in the month | Rate on all of them |
|---|---|
| 251 to 300 | ₹6.75 |
| 301 to 350 | ₹7.60 |
| 351 to 400 | ₹7.95 |
| 401 to 500 | ₹8.25 |
| 501 and above | ₹9.20 |
On top of the energy charge sit a fixed charge that rises with consumption, electricity duty at 10% of the energy charge, and ₹15 a month of meter rent. Figures here are for a single-phase LT-1 domestic connection. A three-phase connection carries a higher fixed charge.
The 250-unit cliff
Crossing 250 units by a single unit reprices everything you used that month. It is the sharpest edge in the tariff, and it is where rooftop solar earns most of its money in Kerala.
- A month of 250 units
- ₹1,751
- Telescopic, all five bands
- A month of 251 units
- ₹2,099
- ₹6.75 on every unit
- What that one unit cost
- ₹348
- ₹696 across a bi-monthly bill
The ₹6.75 charged at 251 units is lower than the ₹8.50 you were paying at the top of the telescopic ladder. The bill still jumps, because that lower rate is applied to all 251 units instead of only to the last fifty. The fixed charge steps up a band at the same point.
KSEB reads domestic meters every two months and applies the slabs to the monthly average, so the test is on the average of the two months rather than on each one. That works slightly in your favour: a heavy month can be carried by a light one inside the same cycle.
Worked example: a 500-unit household
500 units a month is a typical Kerala house with two air conditioners. Its energy charge works out at ₹8.25 a unit. Put enough solar on the roof to halve what KSEB bills, and here is what happens to the bill.
| One month | Today, 500 units | With solar, 250 units billed |
|---|---|---|
| Regime | Non-telescopic, ₹8.25 on everything | Telescopic, five bands |
| Energy charge | ₹4,125 | ₹1,433 |
| Fixed charge | ₹285 | ₹160 |
| Electricity duty (10%) | ₹413 | ₹143 |
| Meter rent | ₹15 | ₹15 |
| Total for the month | ₹4,838 | ₹1,751 |
- Saved every month
- ₹3,087
- Units taken off
- 250
- Worth per unit
- ₹12.35
Half the units, 64% off the bill. Each unit the roof supplied was worth ₹12.35 against a headline rate of ₹8.25, because it came off the top of a non-telescopic bill and pulled the rest of the month back into the telescopic band with it.
What a solar unit is worth to you
The same roof is worth different money to different houses. Every row below halves what KSEB bills, so the only thing that changes is where on the tariff the units are coming from.
| Units a month | Bill today | Bill after | Worth per unit offset | Bill drop |
|---|---|---|---|---|
| 600 to 300 | ₹6,397 | ₹2,463 | ₹13.12 | 62% |
| 500 to 250 | ₹4,838 | ₹1,751 | ₹12.35 | 64% |
| 300 to 150 | ₹2,463 | ₹832 | ₹10.87 | 66% |
| 200 to 100 already telescopic | ₹1,263 | ₹518 | ₹7.45 | 59% |
A household at 200 units is inside the telescopic band already. It has no cliff to fall off, so its units are worth ₹7.45 rather than ₹13.12. A rooftop system still pays for that household. It pays over a longer period, and you should know which of these two cases you are buying before anyone quotes you a payback.
What that does to a real system
Three households in Ernakulam, each sized to cover a year of its own consumption, priced after the PM Surya Ghar subsidy. These come straight from our calculator, so entering the same bill will show you the same numbers.
200 units a month
₹1,263 a month today, about ₹2,526 a bill
- System
- 2 kW
- Subsidy
- ₹60,000
- You pay
- ₹60,000
- Saved each month
- ₹1,209
4.5 years to pay for itself
500 units a month
₹4,838 a month today, about ₹9,676 a bill
- System
- 5 kW
- Subsidy
- ₹78,000
- You pay
- ₹2.02 L
- Saved each month
- ₹4,787
3.7 years to pay for itself
600 units a month
₹6,397 a month today, about ₹12,794 a bill
- System
- 6 kW
- Subsidy
- ₹78,000
- You pay
- ₹2.52 L
- Saved each month
- ₹6,371
3.4 years to pay for itself
The house with the biggest bill pays back fastest, and it draws the same ₹78,000 of subsidy as the one below it. Most people expect the opposite. In a telescopic state the value of a rooftop system is set by which slab it is eating into, so the heaviest consumers get the best returns.
Inflation in energy prices
Every KSERC tariff order since August 2014 has raised domestic rates, and none has cut them. A household using 200 units a month paid ₹900 for energy, fixed charge and duty in 2014. Since the April 2025 revision the same units cost ₹1,248, 39% more.
- 200 units a month, 2014
- ₹900
- Fixed charge ₹20 for every home
- 200 units a month, today
- ₹1,248
- Fixed charge ₹50 to ₹310 by band
- Rise each year, by consumption
- 2.5% to 3.7%
- Our calculator assumes 3%
The fixed charge rose fastest. In 2014 it was a flat ₹20 a month. It now runs from ₹50 to ₹310 depending on how much you use. The rates per unit rose more slowly. The first 50 units went from ₹2.80 to ₹3.35. Fuel surcharge of up to 19 paise a unit has been added on top in some months since 2023.
At 3% a year the 500-unit household above, paying ₹4,838 a month today, would pay about ₹10,129 a month in twenty-five years for the same units. KSEB bills only the units you draw from the grid. The units your roof makes carry no tariff, so each rise touches a smaller part of your consumption. Panels lose a little output each year, and their warranties guarantee at least 80% of rated output in year twenty-five. The paybacks above use today's tariff, which means every increase shortens them. With the rise included, the 600-unit system saves ₹23.74 L over twenty-five years after paying back its own cost.
Why go solar now
The cheapest power in Kerala is already on your roof
Panel prices have fallen, the subsidy is at its most generous, and KSEB tariffs keep climbing. A system bought today usually pays for itself in the first five years of a twenty-five year warranty. The other twenty years are free power.
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Drop out of the expensive slabs
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KSEB charges more per unit the more you use. Below 250 units a month the slabs are telescopic, and above that one higher rate applies to everything. Your last units are your dearest ones, and solar takes those off first. A home paying ₹3,600 every two months usually ends up paying little beyond the standing charges.
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Up to ₹78,000 back from the centre
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PM Surya Ghar pays ₹30,000 per kW for the first two kilowatts and ₹18,000 for the third. Kerala has taken up the scheme faster than almost any other state. The money goes straight into your bank account, and we file the claim for you.
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Your rate stops going up
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KSEB tariffs have climbed steadily, and KSERC revises them on its own schedule. Once your system is running, the units it makes cost you nothing more for the next twenty-five years, whatever the next tariff order says.
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Paid back in three to five years
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After subsidy, most Kerala homes recover the cost inside five years. The bigger your bill, the quicker it happens. Panels are warranted to hold above 80% of rated output in year twenty-five, so you get another two decades of generation after the system has paid for itself.
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Built for salt, damp and lightning
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Salt air corrodes ordinary hardware along the whole coast. Humidity stays high all year. Kerala also records some of the highest lightning strike density in the country. Salt-mist certified modules, marine-grade structure and surge protection are in our standard specification at no extra charge.
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About a tonne of CO₂ a year
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A 3 kW rooftop system in Kerala displaces roughly 3,000 kg of grid generation annually, about what 150 mature trees absorb in a year. Kerala buys in most of its power and a good deal of that is thermal, so what you make at home reduces what the state has to import.
Run your own bill through it
The calculator applies the same slabs to your figure and tells you the system size, the subsidy, the new bill and the payback. About thirty seconds, and nothing to fill in beyond the amount.