Solar for a Low Electricity Bill: Honest Payback Table

Thinking about solar for a low electricity bill, say ₹1,500 to ₹2,500 every two months? Vendors will say yes to everyone. This guide turns KSEB's current slab rates and the PM Surya Ghar subsidy into a simple break-even table, so you can see whether your quote pays back, which size fits, and when waiting is fine.

Key points before you decide

• On a small bill, most of your units sit in KSEB's cheaper slabs, from ₹3.35 to ₹5.35 a unit up to 150 units a month, so each unit solar replaces is worth less.
• The PM Surya Ghar subsidy is ₹30,000 per kW for the first 2 kW and ₹18,000 for the third kW, so small plants get the biggest share of their cost covered.
• Units you export and never use are settled at ₹2.79 a unit for new solar plants, far below what you pay to buy a unit, so an oversized plant does not pay back faster.
• The fixed charge and electricity duty stay on the bill, so solar does not take a small bill to zero.
• Use the break-even table below with your own quote. If the net cost after subsidy is above the 10-year column for your use, waiting is a fair choice.

Many Kerala homes pay a modest bill: a family of three or four, fans, a fridge, a TV, no AC yet. Vendors still call. The honest question is not whether solar works, but whether the money comes back soon enough on a bill this size. This page gives you the arithmetic to answer that for your own house.

How much of a small KSEB bill can solar remove?

KSEB bills most homes every two months, but the tariff slabs are monthly. The table works out the tariff part of a single-phase bill from KSERC's current domestic schedule (valid from 1 April 2025 to 31 March 2027, as of 28 October 2026). Duty and other bill lines come on top. Full slab rules are in our KSEB tariff slabs guide.

So a two-month bill of ₹1,500 to ₹2,500 usually means roughly 150 to 200 units a month. The last column is the most solar could remove in a year if it replaced every unit you buy. It cannot remove the fixed charge, and the schedule says duty and other levies are charged in addition to these rates. Solar homes also choose between fixed-charge options, explained in our guide to fixed charge options for solar homes.

Solar for a low electricity bill: the break-even table

Simple payback is the net cost after subsidy divided by what solar removes from the bill each year. Turn it round and you get the most you can pay and still see the money back in a set number of years. The figures below use today's slab rates and the best case, where solar replaces every unit you buy.

To use it, take the full quote, subtract the subsidy for the plant size, and find your row. If your net cost sits under the eight-year figure, the case for solar is strong on today's rates. If it sits above the ten-year figure, there is no hurry, and the reasons below may tip it either way.

Real paybacks are longer than this table. KSERC's rules first set solar against what the house uses at the same moment. Units sent to the grid are banked after a time-of-day adjustment, and 2% of the banked balance is deducted each month, so a unit exported at noon and used at night is not a full swap. Our guide to solar banking and solar hours shows how that works on the bill.

Is 1 kW, 2 kW or 3 kW the right size for a small bill?

KSERC's rules reckon a net-metered solar plant at a 19% capacity utilisation factor, which is the share of the year it would run at full output. That works out to about 1,664 units a year per kW, or roughly 139 a month, with less in the monsoon. The rules use this figure for battery sizing, so treat it as a rough guide, not a promise. Check your own plant's figures against our guide to daily solar generation.

Match the plant to the units you use in a year. A larger plant than you need sends extra units to KSEB, and new solar plants are paid ₹2.79 a unit for surplus left at the year's end, which is less than even the first slab rate. The subsidy figures are MNRE's fixed amounts.

This is why 2 kW can be the better choice than 3 kW on a small bill. The third kW gets a smaller subsidy, and its units may end up as surplus paid at a low rate. Choose 3 kW only if you expect your use to grow, for example with an AC or an electric vehicle. Our 3 kW, 5 kW and 10 kW size comparison covers bigger homes.

Worked example: a ₹2,300 two-month bill

• Most solar can remove in a year: ₹12,090 of energy charge. The ₹140 monthly fixed charge stays.
• Plant: 2 kW, which on KSERC's 19% figure gives roughly 3,329 units a year against 2,400 used.
• Subsidy: ₹60,000 for 2 kW, paid after KSEB inspects the plant.
• Net cost: the quote minus ₹60,000. If that came to ₹1,00,000, simple payback would be about 8.3 years at best.
• Every ₹10,000 more in net cost adds about 0.8 years to that payback.
• Real payback is longer, because some units are banked at a loss and duty is not removed.

The same family could ask for a smaller plant to cut the surplus, or keep the larger size if an AC is planned next summer. Running the washing machine and pump in daylight also helps, as our guide to using appliances during solar hours explains.

What changes the answer, and when waiting is fine

Three things can change the arithmetic. An AC or a summer spike can push use above 250 units a month, and then KSEB charges one rate on every unit, from ₹6.75 for up to 300 units, so each unit solar replaces is worth more. The current tariff schedule runs to 31 March 2027, and later rates will come from a new KSERC order. Payback here ignores any change, up or down.

Waiting is fine if your use is steady and low, your net cost sits above the ten-year column, or your roof needs repair first. Solar is easier to justify if an AC, induction cooking or an electric vehicle is coming, or your summer bills already cross the higher band. The fuller savings picture, with the long-term view, is on our solar savings guide for Kerala homes.

Checklist before you ask for a quote

• Write down your units for each two-month bill and halve them for the monthly figure.
• Find your row in the bill table and note the yearly energy charge.
• Ask each vendor for a quote by plant size, with the subsidy shown separately.
• Subtract the subsidy and compare the net cost with the break-even table.
• Ask the vendor how much of the generation is likely to be surplus at your use.
• Read how surplus is paid in our guide to surplus settlement before you choose a bigger plant.
• List any big loads you plan to add, such as an AC or an electric vehicle.

If you want a second opinion, send FGE Solar your bill for a free bill and transformer check, or try our Solar Calculator. We will tell you plainly if waiting makes more sense.

Subsidy steps and the documents needed are on our PM Surya Ghar guide for Kerala.

Frequently Asked Questions

Official Sources and Accuracy Note

• 01KSERC Schedule of Tariff and Terms and Conditions for Retail Supply, No. 427/D(T)/2023/KSERC dated 05.12.2024 (OP No. 18/2023), valid to 31.03.2027 (Kerala Gazette)
  Takeaway items 1 and 4: LT-I Domestic table, column w.e.f. 01.04.2025 to 31.03.2027 (telescopic Rs 3.35 to Rs 8.50 per unit up to 250 units; fixed charge per month on top), and the general clause that rates exclude electricity duty.
  govt source · opened 2026-10-28
• 02Guidelines for PM-Surya Ghar: Muft Bijli Yojana, Central Financial Assistance to Residential Consumers (MNRE, mnre.gov.in)
  Takeaway item 2: Section 5(h) effective CFA (Rs 30,000 per kWp for the first 2 kWp, Rs 18,000 for the third, nothing beyond 3 kWp).
  govt source · opened 2026-10-28
• 03KSERC (Renewable Energy and Related Matters) Regulations, 2025 (final PDF)
  Takeaway item 3: Reg 28.6 (surplus banked energy of new prosumers settled at Rs 2.79 per kWh for solar).
  govt source · opened 2026-10-28