If you pay an electricity bill in Maharashtra, you have probably seen an ad promising that rooftop solar will cut it to zero. The real saving is often large, because Mahavitaran charges far more for each unit as a home uses more. But the ads skip the conditions that decide whether you get it.
So we worked it out for two homes: a flat using 150 units a month and a bungalow using 400. A unit is one kilowatt-hour (kWh).
The numbers we used
Tariff. The Maharashtra Electricity Regulatory Commission (MERC) sets the tariff for Mahavitaran, the state distribution company (MSEDCL). Since 1 April 2026 a single-phase home pays a fixed ₹130 a month, plus an energy charge and a ₹1.60 wheeling charge (the fee for using the wires) on every unit. Together: ₹5.56 a unit for the first 100 units, ₹12.40 for units 101 to 300, ₹16.64 for 301 to 500 and ₹19.13 above 500 (MERC tariff order, March 2026). Each rate applies only to units inside its slab, and MERC has kept that rule for homes with rooftop solar (MERC tariff order, March 2025). We leave out the fuel adjustment charge, which Mahavitaran recalculates every month (MERC tariff order, March 2026).
Subsidy and cost. PM Surya Ghar pays ₹30,000 per kilowatt (kW) of panels for the first 2 kW and ₹18,000 for the third, capped at ₹78,000, and the scheme closes on 31 March 2027 (PM Surya Ghar portal, November 2026). For cost we use the benchmark of the Ministry of New and Renewable Energy (MNRE): ₹50,000 per kW for the first 2 kW and ₹45,000 for the third (MNRE scheme guidelines, June 2024).
Output. PVWatts, a solar calculator from a US Department of Energy laboratory, puts 1 kW of south-facing panels in Pune, tilted 18 degrees with 14% system losses, at 1,566 units a year: about 130.5 a month or 4.3 a day, from 105 units in August to 153 in March (PVWatts version 8, November 2026). That fits MNRE’s range of 4 to 5.5 units a day in clear sun (MNRE rooftop solar FAQ, April 2022).
Net metering. Units your panels export are set against units you draw. Surplus carries forward to the next bill, and credit left at the end of the financial year is bought at a generic tariff set by MERC (MERC rooftop regulations, 2019). Homes are exempt from matching by time of day, so a unit made at noon offsets a unit used at night (MERC tariff order, March 2026).
The flat: 1 kW, paid back in under two years
The portal suggests 1 to 2 kW for homes using up to 150 units. We chose 1 kW, because 2 kW would make about 261 units a month, far more than this flat uses.
| Step | Flat, 150 units a month |
|---|---|
| Bill before solar | 100 × ₹5.56 + 50 × ₹12.40 + ₹130 = ₹1,306 |
| Solar output, 1 kW | about 130.5 units |
| Units still billed | 150 − 130.5 = 19.5 |
| Bill after solar | 19.5 × ₹5.56 + ₹130 = ₹238 |
| Monthly saving | ₹1,068, or ₹12,812 a year |
| Cost at benchmark, less subsidy | ₹50,000 − ₹30,000 = ₹20,000 |
| Simple payback | ₹20,000 ÷ ₹12,812 = 1.6 years |
The saving is large because solar removes the 50 units charged at ₹12.40 first. In August the flat still pays for about 45 units, all in the cheapest slab.
The bungalow: 3 kW, and the expensive slabs disappear
| Step | Bungalow, 400 units a month |
|---|---|
| Bill before solar | 100 × ₹5.56 + 200 × ₹12.40 + 100 × ₹16.64 + ₹130 = ₹4,830 |
| Solar output, 3 kW | about 391.6 units |
| Units still billed | 400 − 391.6 = 8.4 |
| Bill after solar | 8.4 × ₹5.56 + ₹130 = ₹177 |
| Monthly saving | ₹4,653, or ₹55,837 a year |
| Cost at benchmark, less subsidy | ₹1,45,000 − ₹78,000 = ₹67,000 |
| Simple payback | ₹67,000 ÷ ₹55,837 = 1.2 years |
The portal suggests more than 3 kW above 300 units. We stopped at 3 kW because the subsidy stops there, and because of the draft rule described below.
If your quote is higher
Vendors set their own prices (MNRE scheme guidelines, June 2024). At 50% above the benchmark, ₹75,000 for the flat and ₹2,17,500 for the bungalow, your cost after subsidy becomes ₹45,000 and ₹1,39,500, and payback stretches to about 3.5 and 2.5 years.
What the ads leave out
Roof space. Each kW needs about 10 to 12 square metres of shade-free roof (MNRE rooftop solar FAQ, April 2022), so the bungalow needs 30 to 36. A flat rarely has a roof of its own. A housing society can claim ₹18,000 per kW for panels serving common areas (PM Surya Ghar portal, November 2026), and shared set-ups such as virtual net metering qualify for the household subsidy if Mahavitaran approves the metering (MNRE scheme guidelines, June 2024).
Net metering limits. Your system cannot exceed your sanctioned load, and Mahavitaran can refuse new connections once rooftop systems on your local transformer reach 70% of its capacity (MERC rooftop regulations, 2019). The rules may also change. A draft MERC regulation from September 2026 would let systems up to 3 kW bank surplus for a year, sold at the average solar-hours market price, but would settle larger systems monthly and let unused surplus lapse (MERC draft rooftop regulations, September 2026). MERC put that market price at ₹2.84 a unit over 2023-24 and 2024-25 (MERC tariff order, March 2025). If adopted, the draft would cover applications made since it was published. One relief: the new grid support charge does not apply to rooftop systems up to 10 kW (MERC tariff order, March 2026).
Maintenance. Vendors under the scheme must give five years of free comprehensive maintenance and a five-year system warranty (MNRE scheme guidelines, June 2024). After that, cleaning and repairs are yours, and dusty or shaded panels will make less than our estimate.
Inverter replacement. The scheme requires panels to keep at least 80% of their rated output for 25 years, and structures and cables to last as long (MNRE scheme guidelines, June 2024). It sets no such life for the inverter, the box that turns the panels’ direct current into the alternating current your home uses. Ask how long its warranty runs, and set money aside to replace it.
For most Mahavitaran homes the arithmetic is strong. The scheme deadline, the 3 kW line in the draft rules and your roof will shape your result more than any promise of a zero bill.