What your system makes
How many units does 1 kW of solar make?
Across India, 1 kW of rooftop solar makes about 4 units a day, 120 a month and 1,440 a year. A 3 kW system makes about 12 units a day or 360 a month; a 5 kW system about 20 a day or 600 a month. The figures below are averages over the year on a clean, shade-free roof facing south.
| System | Units a day | Units a month | Units a year |
|---|---|---|---|
| 1 kW | 3.9 | 120 | 1,440 |
| 2 kW | 7.9 | 240 | 2,880 |
| 3 kW | 11.8 | 360 | 4,320 |
| 4 kW | 15.8 | 480 | 5,760 |
| 5 kW | 19.7 | 600 | 7,200 |
| 10 kW | 39.5 | 1,200 | 14,400 |
Units per kW in every state
Sunshine is what changes the answer. The same kW makes about 1,570 units a year in Rajasthan and about 1,100 in Sikkim. We took each figure from PVGIS, the European Commission’s solar data tool, using 18 years of satellite-based weather for each state capital.
| State or UT | Units per kW a year | Units per kW a day | Best month | Weakest month |
|---|---|---|---|---|
| Ladakh | 1,924 | 5.3 | Mar (184) | Jul (142) |
| Rajasthan | 1,569 | 4.3 | Mar (154) | Aug (93) |
| Haryana | 1,559 | 4.3 | Mar (152) | Jul (96) |
| Delhi | 1,554 | 4.3 | Mar (152) | Jul (96) |
| Punjab | 1,543 | 4.2 | Mar (148) | Jul (103) |
| Chandigarh | 1,541 | 4.2 | Mar (150) | Jul (95) |
| Uttar Pradesh | 1,514 | 4.1 | Mar (153) | Jul (85) |
| Gujarat | 1,511 | 4.1 | Mar (154) | Jul (74) |
| Himachal Pradesh | 1,501 | 4.1 | Mar (144) | Jul (92) |
| Jammu and Kashmir | 1,497 | 4.1 | Oct (140) | Jul (103) |
| Uttarakhand | 1,494 | 4.1 | Mar (146) | Jul (82) |
| Lakshadweep | 1,481 | 4.1 | Mar (149) | Jun (96) |
| Madhya Pradesh | 1,471 | 4.0 | Mar (152) | Jul (69) |
| Bihar | 1,468 | 4.0 | Mar (152) | Jul (85) |
| Puducherry | 1,466 | 4.0 | Mar (147) | Nov (101) |
| Dadra and Nagar Haveli and Daman and Diu | 1,466 | 4.0 | Mar (154) | Jul (68) |
| Karnataka | 1,459 | 4.0 | Mar (151) | Jul (94) |
| Maharashtra | 1,451 | 4.0 | Jan (151) | Jul (74) |
| Telangana | 1,448 | 4.0 | Mar (147) | Jul (84) |
| Jharkhand | 1,445 | 4.0 | Mar (149) | Jul (82) |
| Tamil Nadu | 1,438 | 3.9 | Mar (147) | Nov (101) |
| Goa | 1,435 | 3.9 | Jan (154) | Jul (72) |
| Andaman and Nicobar Islands | 1,433 | 3.9 | Mar (151) | Jun (96) |
| Chhattisgarh | 1,427 | 3.9 | Jan (146) | Jul (72) |
| Odisha | 1,378 | 3.8 | Mar (141) | Jul (82) |
| Andhra Pradesh | 1,373 | 3.8 | Mar (139) | Jul (88) |
| Nagaland | 1,361 | 3.7 | Mar (142) | Jul (84) |
| Manipur | 1,361 | 3.7 | Mar (144) | Jul (79) |
| West Bengal | 1,361 | 3.7 | Mar (142) | Jul (80) |
| Mizoram | 1,338 | 3.7 | Mar (141) | Jul (81) |
| Tripura | 1,312 | 3.6 | Jan (139) | Jun (78) |
| Kerala | 1,288 | 3.5 | Jan (142) | Jun (74) |
| Meghalaya | 1,283 | 3.5 | Jan (135) | Jun (74) |
| Assam | 1,279 | 3.5 | Mar (133) | Jun (77) |
| Arunachal Pradesh | 1,227 | 3.4 | Jan (122) | Jun (76) |
| Sikkim | 1,105 | 3.0 | Mar (113) | Jul (66) |
Why output changes through the year
In most of India, March is the best month: clear skies and long days. Output falls through the monsoon, and July or August is usually the weakest month, at half to two-thirds of March. Kerala and the far south peak in January instead, while Tamil Nadu dips in November with the north-east monsoon. Plan your savings on the yearly total, not the best month.
Why your meter may show less
- Shade. A water tank or a neighbour’s wall that shades even part of a panel string pulls the whole string down.
- Dust. Panels left unwashed through a dry season lose output until the next rain or cleaning.
- Direction. A south-facing roof at the right tilt makes the most. East or west facing panels make less over the day.
- Heat. Panels lose a little output on very hot afternoons. This is already counted in the averages above.
Enter a figure under “Extra loss from shade or dust” in the calculator to see the effect.
Frequently asked questions
How many units does a 3 kW solar system make per day?
About 12 units a day on average across India, or 360 a month. In Rajasthan it is closer to 13 a day; in Kerala or the North East about 10 to 11.
How many units does a 5 kW solar system make per month?
About 600 units a month on average, or 7,200 a year. Expect 650 in the sunniest states and 510 to 550 in the North East.
How many units does 1 kW of solar make in a day?
About 4 units a day across India. It ranges from 3 in Sikkim to 4.3 in Rajasthan.
Does solar work on cloudy days and at night?
Panels still make some power under clouds, a fraction of a sunny day depending on how thick the cloud is. At night they make nothing; a net-metered home draws from the grid then and uses the daytime credit.
How much does output fall as panels age?
Most panels lose about 0.5% a year, so after 25 years a system still makes close to 88% of what it did at the start.
See the formulas on how we calculate. To turn units into rupees and payback, use the solar calculator.