Mumbai Solar Calculator (BEST)
Rooftop solar payback for South Mumbai homes on BEST, where units above 300 a month cost over ₹10 before wheeling and duty.
Updated · By Niraj Kumar · 1 source
https://checkpre.com/energy/solar-calculator-mumbai-best
Your home
About 345 units a month on the BEST tariff. Use a year's average if your bill swings with the seasons.
Fine-tune
Sized to cover a year of your consumption, at 5.4 peak sun hours a day in Maharashtra.
About 100 sq ft per kW. Leave at 0 for no limit.
Typical for an on-grid system from an empanelled vendor. Replace it with your quote.
Indian residential tariffs have historically risen 4-7% a year.
Monocrystalline panels typically lose about 0.5% a year.
A 2.5 kW system makes about 316 units a month, 92% of your use. Your bill drops from ₹3,000 to about ₹243 in year one.
- Installed cost
- ₹1,50,000
- PM Surya Ghar subsidy
- − ₹69,000
- Net cost to you
- ₹81,000
- Saving in year one
- ₹33,187
- Return (IRR)
- 45.3% a year
- over 25 years, before tax
- CO₂ avoided
- 64 tonnes
- over 25 years
- You pay54%
- Central subsidy46%
Year-by-year cash flowShowHide
| Year | Units made | Bills without solar | Bills with solar | Upkeep and EMIs | Running total |
|---|---|---|---|---|---|
| 1 | 3,794 | ₹36,105 | ₹2,918 | ₹0 | -₹47,812 |
| 2 | 3,775 | ₹37,911 | ₹3,160 | ₹0 | -₹13,062 |
| 3 | 3,756 | ₹39,806 | ₹3,418 | ₹0 | ₹23,327 |
| 4 | 3,738 | ₹41,796 | ₹3,693 | ₹0 | ₹61,430 |
| 5 | 3,719 | ₹43,886 | ₹3,987 | ₹0 | ₹1,01,329 |
| 6 | 3,700 | ₹46,080 | ₹4,301 | ₹1,500 | ₹1,41,608 |
| 7 | 3,682 | ₹48,384 | ₹4,635 | ₹1,500 | ₹1,83,858 |
| 8 | 3,663 | ₹50,804 | ₹4,992 | ₹1,500 | ₹2,28,170 |
| 9 | 3,645 | ₹53,344 | ₹5,372 | ₹1,500 | ₹2,74,642 |
| 10 | 3,627 | ₹56,011 | ₹5,776 | ₹1,500 | ₹3,23,377 |
| 11 | 3,609 | ₹58,812 | ₹6,207 | ₹1,500 | ₹3,74,481 |
| 12 | 3,591 | ₹61,752 | ₹6,666 | ₹19,000 | ₹4,10,567 |
| 13 | 3,573 | ₹64,840 | ₹7,155 | ₹1,500 | ₹4,66,751 |
| 14 | 3,555 | ₹68,082 | ₹7,675 | ₹1,500 | ₹5,25,659 |
| 15 | 3,537 | ₹71,486 | ₹8,228 | ₹1,500 | ₹5,87,416 |
| 16 | 3,519 | ₹75,060 | ₹8,816 | ₹1,500 | ₹6,52,160 |
| 17 | 3,502 | ₹78,813 | ₹9,442 | ₹1,500 | ₹7,20,031 |
| 18 | 3,484 | ₹82,754 | ₹10,108 | ₹1,500 | ₹7,91,178 |
| 19 | 3,467 | ₹86,892 | ₹10,814 | ₹1,500 | ₹8,65,755 |
| 20 | 3,449 | ₹91,236 | ₹11,566 | ₹1,500 | ₹9,43,925 |
| 21 | 3,432 | ₹95,798 | ₹12,365 | ₹1,500 | ₹10,25,858 |
| 22 | 3,415 | ₹1,00,588 | ₹13,213 | ₹1,500 | ₹11,11,733 |
| 23 | 3,398 | ₹1,05,617 | ₹14,114 | ₹1,500 | ₹12,01,736 |
| 24 | 3,381 | ₹1,10,898 | ₹15,071 | ₹1,500 | ₹12,96,062 |
| 25 | 3,364 | ₹1,16,443 | ₹16,087 | ₹1,500 | ₹13,94,918 |
How the Mumbai Solar Calculator (BEST) works
Saving₍y₎ = [Bill(U) − Bill(U − G₍y₎/12)] × 12 × (1 + e)^(y−1), G₍y₎ = kW × H × 365 × PR × (1 − d)^(y−1)This page uses the same method as the Solar ROI Calculator India, which explains each term and assumption in full.
Worked example
A Mumbai home on BEST with a ₹4,000 monthly bill and a flat RCC roof, assuming prices rise 5% a year.
- 1Working the bill back through the BEST slabs, charges and duty gives about 415 units a month
- 2At 5.4 peak sun hours, 3.5 kW makes about 443 units a month, 100% of that use
- 33.5 kW at ₹55,000 per kW costs ₹1,92,500; PM Surya Ghar pays ₹78,000, leaving ₹1,14,500
- 4The first year saves ₹47,673, and the saving grows as tariffs rise
The system pays for itself in about 2.3 years and leaves the household about ₹20,36,555 ahead over 25 years.
Frequently asked questions
Why does solar pay back fast for large BEST bills?
BEST's energy charge jumps from about ₹5.35 to ₹10.04 a unit above 300 units a month and to ₹11.25 above 500. A home using 500 units saves its dearest units first, so the first few kilowatts of panels earn far more than the average rate suggests.
Who supplies electricity in South Mumbai?
BEST supplies the island city, from Colaba to Mahim and Sion. Tata Power also has consumers across the city and suburbs, Adani Electricity serves the western suburbs, and MSEDCL serves Thane and Navi Mumbai. The DISCOM's name is printed at the top of your bill.
How does net metering settle on BEST?
Surplus units are banked month to month and settled once a year at the MERC-approved rate. MERC has confirmed that residential net metering continues under the new ToD meters, with banked units usable at any hour.
Sources
Related calculators
- Maharashtra Solar CalculatorCompare rooftop solar payback across Maharashtra's four residential DISCOMs: MSEDCL, Adani Electricity, Tata Power and BEST.
- Mumbai Solar Calculator (Adani Electricity)Rooftop solar payback for Mumbai's western suburbs on Adani Electricity, with the wheeling charge, 16% duty and the society subsidy.
- Mumbai Solar Calculator (Tata Power Mumbai)Rooftop solar payback for Mumbai homes on Tata Power, on MERC's FY 2026-27 schedule with its ₹2.40 wheeling charge.
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