Solar Generation Per kW Per Day by City
| City | Peak Sun Hours | Units/kW/Day | 3kW Monthly Output |
|---|
| Jodhpur | 5.8 | 4.6 | ~418 units |
| Jaipur | 5.5 | 4.4 | ~396 units |
| Ahmedabad | 5.3 | 4.2 | ~382 units |
| Indore | 5.2 | 4.2 | ~374 units |
| New Delhi | 5.0 | 4.0 | ~360 units |
| Hyderabad | 5.0 | 4.0 | ~360 units |
| Nagpur | 4.8 | 3.8 | ~346 units |
| Chennai | 4.8 | 3.8 | ~346 units |
| Bengaluru | 4.8 | 3.8 | ~346 units |
| Mumbai | 4.5 | 3.6 | ~324 units |
| Kolkata | 4.2 | 3.4 | ~302 units |
| Kochi | 4.2 | 3.4 | ~302 units |
A handy rule for India: 1 kW of solar generates about 4 units per day, 120 units per month and 1,400 to 1,500
units per year in most cities. Rajasthan and Gujarat run higher; coastal, eastern and hill regions run lower.
Why Real Output Is Below the Nameplate Rating
A 1 kW array never delivers 1 kW × 24 hours. Sunlight is only strong for a few "peak sun hours" a day, and the
system loses 15 to 25% to heat, dust, wiring and inverter conversion, captured here as a 0.8 performance ratio.
Monsoon months dip 30 to 40% below average while March to May run above it. If your goal is checking a real
system against expectations, compare monthly bills or inverter logs against the range this
calculator shows, and check your panel's rated efficiency with the
solar panel efficiency calculator.
Entering the Right kW: Nameplate, Not Wishes
The kW field wants your array's DC nameplate capacity: the sum of panel wattages divided by 1,000. Pull it
from the quote ("10 × 550W = 5.5 kW") or count the panels on an existing roof. Three input subtleties change
the answer:
- Array kW, not inverter kW. A 5.5 kW array on a 5 kW inverter generates like a 5.5 kW
array for most of the day; enter 5.5.
- City honesty. Generation scales directly with sun hours; using Delhi's 5.0 for a home in
Siliguri (4.0) inflates the estimate by 25%.
- Existing systems: if your panels are 8+ years old, mentally shave ~0.5% per year of age
from the result before comparing against your meter.
Worked Example: 5kW Generation in Ahmedabad
A 5 kW array in Ahmedabad (5.3 peak sun hours) produces about 21.2 units a day, or
636 units a month with a healthy-system band of 596 to 676. Across the year that is roughly
7,738 units. The monthly reality behind the average: March to May will clear 700, while July and August may
dip near 420. If this array powered a home using 500 units a month, the surplus of 130+ units would bank
under net metering during strong months and cover the monsoon gap.
Using the Estimate: Benchmarks and Monitoring
- Set a monthly ritual. Note the inverter's monthly kWh on the 1st; compare against this
calculator's low band. Above the band: enjoy. Inside: normal. Below by 15%+: act.
- First suspect is dirt. A hose-down recovers most shortfalls; if generation does not
bounce back within a week, look for new shading or call for a string-voltage check.
- Convert units to rupees. Multiply monthly units by your tariff in the
savings calculator to see what the generation is actually
worth.
- Keep the commissioning report. The day-one generation figure is your lifetime baseline
for warranty arguments about degradation.
Generation Estimation Mistakes
- Judging a system by one monsoon month. July output 35% below average is design, not
defect; annual totals are the test.
- Expecting nameplate at noon. A 5 kW array peaking at 4.2 kW on a hot afternoon is
healthy; cell temperature derating is physics, not fraud.
- Comparing DC capacity with AC readings. Inverter output includes conversion losses; the
0.8 performance ratio here already bridges that gap.
- Ignoring orientation penalties. This estimate assumes near-south facing; a fully east or
west array runs 10 to 15% below these numbers by design.
How This Generation Calculator Works
Daily units = System kW × Peak sun hours × 0.8
Monthly units = Daily × 30 (range uses 0.75 – 0.85 performance)
Annual units = Daily × 365
Assumptions
- Peak sun hours: city-level averages for 90+ Indian cities stored in this site's engine
- Performance ratio: 0.8 typical for clean, well-installed rooftop systems
- Seasonality: figures are annualised averages; monsoon runs lower and summer higher
To turn generation into money, continue to the solar savings
calculator or see the bill impact in the
electricity bill calculator.
