Inputs
Provide your daily energy use and site conditions. Advanced loss settings help mirror real‑world output.
Formula used
This tool estimates the DC array size needed to meet a daily energy target under average site conditions:
- Performance factor = (BaseDerate × InverterEff × (1−losses...))
- Required array (kW) = Daily_kWh ÷ (PeakSunHours × PerformanceFactor)
- Panel count = ceil(RequiredArray_W ÷ PanelWatt)
- Recommended inverter (kW) = ActualArray_kW ÷ DC/AC_ratio
For on‑grid systems, this provides planning‑level sizing. Final designs should consider orientation, local codes, voltage limits, and utility interconnection rules.
How to use this calculator
- Find your average daily usage from your electricity bill.
- Enter local peak sun hours (annual average is best).
- Select your planned module wattage.
- Adjust losses to match your site: dust, shade, temperature.
- Press Submit to see results above the form.
- Export CSV or PDF for sharing and quoting.
Example data table
Sample scenarios below show how sunlight and losses change panel count.
| Scenario | Daily kWh | Sun hours | Panel W | Derate (approx.) | Estimated panels |
|---|---|---|---|---|---|
| Small home, clear roof | 10 | 5.5 | 550 | 0.78 | 5 |
| Medium home, moderate dust | 18 | 5.2 | 550 | 0.73 | 9 |
| Large home, hot climate | 30 | 5.6 | 500 | 0.69 | 16 |
| Apartment load, limited sun | 7 | 4.2 | 450 | 0.75 | 5 |
| Shop, light shading | 25 | 5.0 | 600 | 0.70 | 12 |
These are illustrative numbers. Your actual derate depends on hardware quality, wiring, design choices, and site specifics.