How to use
- Fill in: Monthly electricity use (units / kWh), Peak sun hours per day, Panel wattage (W), Backup load (W), Backup hours and Battery type (if backup). Fields with defaults or marked optional can stay as shown.
- Tap Size My Solar System.
- Read the result - you can print or save it as PDF.
Worked example
With Monthly electricity use = 300, Peak sun hours per day = 4.5, Panel wattage = 450, Backup load = 1000, Backup hours - optional = 5, Battery type = Lithium (85% usable):
REQUIRED SYSTEM SIZE2.8 kWp
- Required system size: 2.8 kWp (target)
- Panels (450 W each): 7 nos = 3.15 kWp installed
- Shadow-free roof area: 28 - 33 m²
- Daily need: 10 units (kWh)
- Battery for 5 h backup: 5.9 kWh nominal (lithium at 85% DoD)
- Inverter for 1,000 W backup load: 1.3 kW or above (25% margin)
Sizing: array kWp = daily units ÷ (peak sun hours × 80% system efficiency). 1 kWp needs 10-12 m² shadow-free roof and generates about 4-5.5 units/day (PIB, Govt of India). Peak sun hours vary by city - 4.5 is a central-India planning figure, edit it for your location. Panels are rounded up to whole units, so installed capacity slightly exceeds the target. Battery and inverter are shown only if you enter a backup load.
