Solar System Input Form
Use this calculator to estimate daily solar array size, battery capacity, inverter rating, and savings from regular energy use.
Example Data Table
This sample helps estimate a realistic daily household energy profile before sizing the solar system.
| Appliance | Quantity | Power Each (W) | Hours/Day | Daily Energy (Wh) |
|---|---|---|---|---|
| LED lights | 8 | 12 | 6 | 576 |
| Fans | 4 | 70 | 8 | 2240 |
| Refrigerator | 1 | 180 | 10 | 1800 |
| Television | 1 | 100 | 4 | 400 |
| Laptop | 2 | 65 | 3 | 390 |
| Total Daily Load | 5406 Wh | |||
Formula Used
1. Daily load in watt-hours
Daily Load (Wh) = Daily Load (kWh) × 1000
2. Adjusted DC energy demand
Adjusted DC Load = (Daily Load ÷ Inverter Efficiency) × (1 + Safety Margin)
3. Required solar array size
Array Wattage = Adjusted DC Load ÷ (Peak Sun Hours × Performance Ratio)
4. Panels required
Panel Count = Ceiling(Array Wattage ÷ Panel Wattage)
5. Battery usable energy target
Battery Usable Energy = Adjusted DC Load × Battery Autonomy Days
6. Battery nominal bank energy
Battery Nominal Energy = Battery Usable Energy ÷ Depth of Discharge
7. Battery bank capacity
Battery Bank Ah = Battery Nominal Energy ÷ System Voltage
8. Inverter recommendation
Recommended Inverter = Higher Load × (1 + Safety Margin)
These formulas simplify engineering estimates for everyday design checks. Final installations should still follow site survey data, wiring losses, local codes, and manufacturer limits.
How to Use This Calculator
- Enter your daily energy use in kWh.
- Add realistic peak sun hours for your location.
- Choose the panel wattage you plan to buy.
- Enter performance ratio to include wiring and temperature losses.
- Set battery autonomy days and allowed depth of discharge.
- Define system voltage and inverter efficiency.
- Enter continuous, surge, and safety margin values.
- Set battery unit voltage and amp-hour rating.
- Optionally add your electricity tariff for savings estimates.
- Press calculate to view sizing, graph, and export options.
Frequently Asked Questions
1. What does peak sun hours mean?
Peak sun hours represent equivalent full sunlight received during a day. It converts changing sunlight conditions into one design value for panel energy estimation.
2. Why is performance ratio important?
Performance ratio captures practical losses from temperature, dust, mismatch, controller behavior, and wiring. It keeps the estimate closer to real operating conditions.
3. Why does the calculator use a safety margin?
The safety margin protects the design from demand growth, seasonal changes, small miscalculations, and unexpected inefficiencies. Larger systems generally operate more comfortably.
4. What is battery autonomy?
Battery autonomy is the number of days your system should supply power without enough solar recharge. It directly increases required battery storage capacity.
5. Why is depth of discharge limited?
Depth of discharge controls how much stored energy you regularly use. Lower discharge often improves battery lifespan, especially for lead-acid systems.
6. Should inverter size match continuous load only?
No. Many appliances have startup surges. The inverter must support continuous power and short surge demand without instability or shutdown.
7. Are savings estimates exact?
No. Savings here are simple estimates based on entered load and tariff. Real savings depend on weather, usage changes, maintenance, and local billing rules.
8. Can this calculator replace a full engineering design?
No. It is excellent for planning and comparison, but final designs should include conductor sizing, protection devices, site shading, structure, and code compliance.