Solar Panel System Sizing Calculator
Estimate solar array size and battery capacity based on location (Peak Sun Hours) and energy usage. Accurate engineering sizing tool.
About
Designing a photovoltaic (PV) system requires more than just summing up wattage. The critical variable is 'Peak Sun Hours'-not the length of the day, but the number of hours where solar irradiance equals 1000 watts per square meter. A location might have 12 hours of daylight but only 4.5 peak sun hours due to angle and atmospheric conditions.
This engineering tool calculates the required array size to offset 100% of your usage, accounting for typical system inefficiencies (inverter losses, wiring voltage drop, and panel degradation). It also sizes a battery bank for autonomy, ensuring power availability during night or cloudy days based on your specific daily consumption.
Formulas
The required array size in kW is calculated using daily consumption and local insolation:
Battery Bank Capacity for N days of autonomy (DoD = Depth of Discharge):
Reference Data
| Component | Loss Factor | Description |
|---|---|---|
| Inverter Efficiency | 90% - 96% | Loss converting DC (Panels) to AC (Home). |
| Battery Round-Trip | 80% - 95% | Energy lost charging and discharging. LiFePO4 is more efficient than Lead-Acid. |
| Wiring/Dust | 5% - 10% | Voltage drop and panel soiling. |
| Total Derating | 1.3x | Multiplier applied to array size to compensate for real-world losses. |