Solar Generation Calculator: Units from Your Solar System
Enter your solar system size, peak sun hours and performance ratio. You get units per day, month and year, yearly savings and a 25-year table with panel ageing.
- Nothing you type is stored
- Free
- No signup
Units per month
365units (kWh)
- Units per day
- 12 units (kWh)
- Units per year
- 4,380 units (kWh)
- Savings per year
- ₹30,660
- Units in 25 years
- 1,03,175 units (kWh)
Estimate only. Real results depend on your equipment, its age and conditions.
Show working
- 3 kW × 5 h × 0.8 = 12 kWh/day
- 12 × 365 = 4,380 kWh
Year by year
| Year | Units | Savings |
|---|---|---|
| 1 | 4,380 | ₹30,660 |
| 2 | 4,358.1 | ₹30,507 |
| 3 | 4,336.31 | ₹30,354 |
| 4 | 4,314.63 | ₹30,202 |
| 5 | 4,293.05 | ₹30,051 |
| 6 | 4,271.59 | ₹29,901 |
| 7 | 4,250.23 | ₹29,752 |
| 8 | 4,228.98 | ₹29,603 |
| 9 | 4,207.84 | ₹29,455 |
| 10 | 4,186.8 | ₹29,308 |
| 11 | 4,165.86 | ₹29,161 |
| 12 | 4,145.03 | ₹29,015 |
| 13 | 4,124.31 | ₹28,870 |
| 14 | 4,103.69 | ₹28,726 |
| 15 | 4,083.17 | ₹28,582 |
| 16 | 4,062.75 | ₹28,439 |
| 17 | 4,042.44 | ₹28,297 |
| 18 | 4,022.23 | ₹28,156 |
| 19 | 4,002.12 | ₹28,015 |
| 20 | 3,982.1 | ₹27,875 |
| 21 | 3,962.19 | ₹27,735 |
| 22 | 3,942.38 | ₹27,597 |
| 23 | 3,922.67 | ₹27,459 |
| 24 | 3,903.06 | ₹27,321 |
| 25 | 3,883.54 | ₹27,185 |
How to use
- Enter the system size in kW.
- Enter peak sun hours (India 4.5–5.5) and performance ratio (75–85%).
- Enter your rate per unit to see savings.
Good to know
Units per day = kW × peak sun hours × performance ratio. A 3 kW system at 5 sun hours and 80% gives 12 units a day, about 365 a month and 4,380 a year.
Performance ratio covers heat, dust, cable and inverter losses: 75–85% for a clean, well-installed rooftop system. Shade from tanks, trees or nearby buildings can cut output far more, so keep panels in full sun from about 9 am to 4 pm.
Panels slowly lose output, commonly about 0.4–0.7% a year after the first year (check your panel’s warranty). The 25-year table applies the degradation % you enter. Savings assume each unit replaces a unit you would have bought at your rate.
Questions
How many units does a 3 kW solar system generate?
About 12 units a day (360–370 a month) at 5 sun hours and 80% performance ratio.
How many units per day from 1 kW?
About 4 at 5 sun hours and 80%; MNRE quotes 4–5.5 units on a clear day.
Why is output lower in monsoon?
Clouds cut sun hours. Yearly averages balance high summer and low monsoon months.
What is performance ratio?
The share of ideal output you actually get after heat, dust, wiring and inverter losses.
How much do panels degrade?
Typically 0.4–0.7% a year; see your panel maker’s performance warranty.