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How to use
- Enter Panel watts.
- Enter Panels.
- Enter Peak sun hours.
- Enter System efficiency %.
- Calculate, then review power, price and period before comparing.
How it is calculated
Daily kWh = panel W × count ÷1000 × sun hours × efficiency
Example
Ten 450 W panels make a 4.5 kW array; with 5.5 sun hours and 80% system efficiency, estimated daily output is 19.8 kWh.
Important notes
Peak sun hours are not daylight hours. The efficiency input simplifies inverter, temperature, wiring, orientation and soiling losses.
Worked examples and interpreting results
| Case | Calculation | Result |
|---|---|---|
| Array size | 450 × 10 ÷ 1000 | 4.5 |
| Daily output | 4.5 × 5.5 × 0.8 | 19.8 |
Frequently asked questions
Is 80% efficiency fixed?
No. It is a planning assumption and should be adjusted for the system and site.
Is the result an actual utility bill?
No. It is a calculation from your usage, price and inputs; real tariffs, taxes and fixed fees may add other items.
How can I improve accuracy?
Use measured or device-specific power and usage plus the actual electricity price for the same period.