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How to use
- Enter Target daily energy kWh.
- Enter Panel watts.
- Enter Peak sun hours.
- Enter System efficiency %.
- Calculate, then review power, price and period before comparing.
How it is calculated
Panels = daily energy ÷ (panel kW × sun hours × efficiency), rounded up
Example
A 450 W panel with 5.5 sun hours and 80% efficiency produces about 1.98 kWh daily; 30 kWh requires 16 panels after rounding up.
Important notes
This is an energy-only estimate. Roof area, shade, orientation, inverter limits and interconnection rules can change the practical panel count.
Worked examples and interpreting results
| Case | Calculation | Result |
|---|---|---|
| Per-panel output | 0.45 × 5.5 × 0.8 | 1.98 |
| Panels needed | ceil(30 ÷ 1.98) | 16 |
Frequently asked questions
Why round up?
A fraction of a panel cannot be installed, so the integer count must cover the target energy.
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.