- Energy use of a 30 W LED for 10 hours a night: 109.5 kWh a year.
- Base-case 10-year cost: grid Rs 50,700, solar Rs 58,000.
- Break-even tariff on a 10-year view: about Rs 16.7 per unit (all-in).
- Extra grid-side cost that flips the answer to solar: about Rs 7,300 per pole.
- With 5% yearly tariff growth, grid's 15-year cost is about Rs 69,900 against Rs 63,000 for solar.
Why a 10-year view (and a 15-year one)
The purchase price is the only number that shows up clearly in a council meeting. The electricity bill, the trench, the driver replacement and the battery all arrive later, often in someone else's budget line. A total cost of ownership (TCO) view puts them side by side.
We show 10 years because that is how most budgets are argued, and 15 years because a decorative pole lasts much longer than that and the picture shifts.
Assumptions (change these to match your site)
| Parameter | Value used | Notes |
|---|---|---|
| LED wattage | 30 W | Typical for colony and village roads (IS 1944 Group B) |
| Operating hours | 10 hours a night, 365 nights | 109.5 kWh per year |
| All-in electricity cost | Rs 10 per unit | Energy + wheeling + fixed + FAC + duty, averaged. Check your own street light bill under the current MERC order. |
| Pole spacing / trench per pole | 25 m | Single-side layout |
| Trench cost | Rs 250 per metre | Normal soil, unpaved verge |
| Grid connection share | Rs 3,000 per pole | Assumes an LT line is already close |
| Grid pole + fitting | Rs 20,000 | |
| Solar pole + fitting | Rs 45,000 | LiFePO4 battery |
| Maintenance | Grid Rs 800/yr; solar Rs 500/yr | Cleaning, checks, minor repairs |
| Replacements | Grid LED/driver Rs 2,500 in years 6 and 12; solar battery Rs 8,000 in year 9, controller Rs 2,500 in year 12 |
Year-by-year cumulative cost
| Year | Solar (cumulative) | Grid, flat tariff | Grid, tariff +5%/yr |
|---|---|---|---|
| 0 (install) | Rs 45,000 | Rs 29,250 | Rs 29,250 |
| 2 | Rs 46,000 | Rs 33,040 | Rs 33,095 |
| 4 | Rs 47,000 | Rs 36,830 | Rs 37,170 |
| 6 (grid driver) | Rs 48,000 | Rs 43,120 | Rs 43,998 |
| 8 | Rs 49,000 | Rs 46,910 | Rs 48,606 |
| 9 (solar battery) | Rs 57,500 | Rs 48,805 | Rs 51,024 |
| 10 | Rs 58,000 | Rs 50,700 | Rs 53,523 |
| 12 (replacements) | Rs 61,500 | Rs 56,990 | Rs 61,279 |
| 13 | Rs 62,000 | Rs 58,885 | Rs 64,046 |
| 15 | Rs 63,000 | Rs 62,675 | Rs 69,879 |
Two things stand out. Solar starts about Rs 15,750 behind and closes the gap slowly, then loses ground in year 9 when the battery is replaced. And tariff growth matters: at 5% a year, solar is ahead from year 13 and about Rs 6,900 ahead by year 15.
What changes the answer
| Scenario | Grid 10-year cost | Solar 10-year cost | Cheaper over 10 years |
|---|---|---|---|
| Base case (Rs 10/unit, Rs 250/m) | Rs 50,700 | Rs 58,000 | Grid |
| Tariff Rs 8/unit | Rs 48,510 | Rs 58,000 | Grid |
| Tariff Rs 12/unit | Rs 52,890 | Rs 58,000 | Grid |
| Tariff Rs 15/unit | Rs 56,175 | Rs 58,000 | Grid, narrowly |
| Trench Rs 400/m | Rs 54,450 | Rs 58,000 | Grid, narrowly |
| Trench Rs 600/m, 30 m spacing (rocky or paved) | Rs 62,450 | Rs 58,000 | Solar |
| Rs 12/unit + Rs 400/m + 35 m spacing | Rs 60,640 | Rs 58,000 | Solar |
| Grid extension adds more than Rs 7,300 per pole | Above Rs 58,000 | Rs 58,000 | Solar |
| Solar gets 30% capital support (if a state scheme offers it) | Rs 50,700 | Rs 44,500 | Solar |
The costs no spreadsheet shows
- Outages: if the road goes dark for two hours every evening, the grid pole is not delivering what you paid for. Solar keeps working.
- Theft: copper cable theft is a real cost on some grid routes; panel and battery theft is a risk for solar. Anti-theft fasteners and battery placement help.
- Disruption: trenching a finished road means dust, traffic diversions and repair work. Solar avoids it.
- Shade: a solar pole under a big tree underperforms every day. Grid does not care.
How to run this for your own project
- Take your last street light electricity bill and divide the total amount by the units billed. That is your all-in rate.
- Measure the actual cable route per pole, and get a trench rate for your soil and surface.
- Ask both suppliers for replacement costs (driver, battery, controller) in writing.
- Plug them into the table above, or send them to us and we will do it for you.
For a simpler decision guide, see Solar vs Electric Decorative Street Lights.
References
- MERC Multi-Year Tariff Order for MSEDCL, FY 2025-26 to FY 2029-30 (28 March 2025) — summary circular — DCCIA Pune (citing MERC)
- MERC Order dated 25 March 2026 on MSEDCL review petition — summary circular — DCCIA Pune (citing MERC)
- MNRE scraps second phase of AJAY solar streetlights program (27 April 2020) — Mercom India
- IS 1944 (Parts 1 & 2): Code of Practice for Lighting of Public Thoroughfares — Bureau of Indian Standards
Frequently Asked Questions
At what electricity tariff does solar become cheaper than grid?
In our base model (30 W, 10 hours a night, Rs 250/m trench, 25 m spacing), solar is cheaper over 10 years only above about Rs 16.7 per unit all-in. Over 15 years, or with rising tariffs, the break-even point comes much sooner.
Does the battery replacement make solar less attractive?
It is the biggest single cost for solar, about Rs 8,000 in year 9 in our model. It is the reason solar falls back around year 9 before catching up again.
Is there a government subsidy on solar street lights?
Not a general central one. MNRE's Atal Jyoti Yojana ended in 2020. If your state offers capital support, a 30% subsidy would cut solar's 10-year cost to about Rs 44,500, making it cheaper than grid.
How do I find my real electricity cost per unit?
Divide the total amount on your street light bill by the units billed. This captures energy charge, wheeling, fixed charges, fuel adjustment and duty together.
सोलर कब तुरंत सस्ता पड़ता है?
जब केबल डालने का खर्च ज़्यादा हो (जैसे पक्की या पथरीली सड़क), पोल दूर-दूर हों, या बिजली लाइन बढ़ानी पड़े। हमारे मॉडल में ग्रिड की तरफ प्रति पोल 7,300 रुपये से ज़्यादा अतिरिक्त खर्च हो तो सोलर सस्ता है।
15 वर्षांचा हिशोब का पाहावा?
कारण पोल 20 वर्षांहून अधिक टिकतो. 15 वर्षांत ग्रिड आणि सोलर जवळपास समान येतात आणि विजेचे दर वाढल्यास सोलर पुढे जातो.
