Calculator Inputs
This page keeps a single-column flow. The input controls use a responsive grid: three columns on large screens, two on smaller screens, and one on mobile.
Example Data Table
| Scenario | Daily Load | Sun Hours | Battery Voltage | Panel Power | Autonomy | Estimated Array | Estimated Battery Bank |
|---|---|---|---|---|---|---|---|
| Remote cabin | 6,500 Wh/day | 5.2 h | 48 V | 550 W | 2 days | ~1.85 kW | ~654 Ah @ 48 V |
| Farm pump shed | 4,100 Wh/day | 5.8 h | 24 V | 450 W | 1.5 days | ~1.13 kW | ~515 Ah @ 24 V |
| Workshop backup | 9,200 Wh/day | 4.7 h | 48 V | 600 W | 2.5 days | ~2.88 kW | ~1,285 Ah @ 48 V |
These figures are illustrative. Final engineering decisions should also consider local temperature, cable runs, module temperature coefficients, code requirements, and future load growth.
Formula Used
Daily DC Energy = Daily AC Load ÷ Inverter Efficiency
Required PV Energy = Daily DC Energy ÷ (1 − System Losses)
Array Size (W) = (Required PV Energy ÷ Peak Sun Hours) × PV Safety Factor
Panel Count = Ceiling(Array Size ÷ Panel Power)
Battery Storage (Wh) = (Daily AC Load × Autonomy Days) ÷ (Depth of Discharge × Battery Efficiency × Inverter Efficiency)
Battery Bank (Ah) = Battery Storage (Wh) ÷ Battery System Voltage
Recommended Inverter = Peak Load × Inverter Safety Factor
Controller Current = (Actual Array Power ÷ Battery Voltage) × Controller Safety Factor
How to Use This Calculator
Enter your daily energy demand in watt-hours. Use a realistic value from appliance measurements, energy bills, or a load schedule.
Add the highest simultaneous running load in watts. This helps size the inverter for continuous power and startup margin.
Enter local peak sun hours. This should reflect your site, season, and design month rather than ideal annual averages.
Set losses for dust, wiring, temperature, mismatch, and conversion losses. Conservative estimates improve reliability.
Choose autonomy days, battery voltage, discharge limit, and battery unit details. These inputs determine storage size and battery count.
Enter panel power, panel area, controller type, and module voltages. The calculator suggests array size, rough stringing, and controller rating.
Press Calculate PV System. The result appears above the form, directly below the header.
FAQs
1) What does peak sun hours mean?
Peak sun hours represent equivalent full solar intensity hours for one day. It is not daylight length. It converts local solar resource into usable design energy for array sizing.
2) Why does the calculator use system losses?
Real PV systems lose energy through heat, dust, wiring, controller conversion, inverter conversion, and module mismatch. Including losses avoids undersizing and gives more realistic engineering estimates.
3) Why is battery efficiency separate from inverter efficiency?
Battery efficiency accounts for storage charging and discharging losses. Inverter efficiency covers DC-to-AC conversion. Keeping them separate improves storage sizing for off-grid and backup applications.
4) What is autonomy days?
Autonomy is the number of days the battery bank should support the load without meaningful charging. Higher autonomy increases resilience but also raises battery count, space, and cost.
5) Why use safety factors?
Safety factors provide room for aging, weather variation, wiring tolerances, future load growth, and equipment derating. They reduce the risk of a system performing below expectations.
6) Is the suggested panel stringing final?
No. It is a preliminary recommendation. Final string design should consider low-temperature Voc rise, controller operating window, cable limits, and installation code requirements.
7) Can I use this for grid-tied systems?
Yes, for early estimates of array size and monthly production. Battery and autonomy sections are most useful for off-grid, hybrid, and backup systems.
8) Should this replace a detailed engineering review?
No. It is a planning calculator. Final design should verify conductor sizing, protective devices, structural loading, module temperature behavior, local code compliance, and manufacturer limits.