Off-Grid Solar System Sizing Calculator | Evergreen Off-Grid DIY Tool
Evergreen Off-Grid, LLC
Off-Grid Solar Sizing Calculator
Battery storage is required for off-grid systems. Enter your state, add loads (we’ll estimate watts if unknown), choose days of autonomy, and set a safety factor. The tool sizes PV, inverter, MPPT “DC charger,” battery bank, and key DC wiring—and runs capacity checks. Overloaded parts show a big warning and no suggested size.
1) Location & System Preferences
Ampacity note: Very simplified copper THHN-ish ampacity ladder for guidance — estimated at 60 °C up to 1 AWG, then 75 °C above that. Always verify with code tables, temperature corrections, and your AHJ.
2) Add Your Loads (Name, Watts, Hours/Day)
Leave watts blank and we’ll estimate from the name (e.g., “LED light”, “laptop”, “mini fridge”, “router”, “TV”, “well pump”). Some loads include duty cycles.
| Item | Qty | Watts (optional) | Hours/Day | Daily Wh |
|---|
Start with lights, fridge, laptop/PC, network gear, pumps, etc.
Results & Recommendations
All core components meet or exceed the calculated system amperage.
Load Summary
Daily Energy
Peak Load (est.)
PSH Used
Solar & Power Hardware
Based on daily energy, PSH, losses & safety factor. Panel count assumes ~400 W modules.
If overloaded, no size is shown. Continuous above peak; surge ~2× for motors/compressors.
If overloaded, no size is shown. Current based on array power at battery voltage, plus margin.
Auto-selected for efficiency; you can force 12/24/48 V above.
Battery Bank (Required)
Battery size controls how long you can run without sun (days of autonomy). More autonomy → more kWh, weight, and cost. Fewer days → smaller bank, but more generator use and careful energy management.
Assumes LiFePO₄ (~80% usable DoD, ~95% charge efficiency). Adjust in detailed designs.
Example using 12 V, 100 Ah LiFePO₄ modules (≈1.28 kWh each). Use equal-length cables, proper busbars, and listed lugs.
Wiring & Protection (Overview)
Guidance only. Verify with conductor ampacity, voltage-drop checks, terminations rated for the chosen conductor, and your local code/AHJ. Keep battery-to-inverter DC cables short (often ≤ 3 ft per leg).
Disclaimer: This Off-Grid Solar System Sizing Calculator is provided for informational and educational purposes only.
Results are based on user inputs and estimation methods. Actual requirements vary by site conditions, equipment, and installation practices.
Always consult a licensed electrician/engineer and follow manufacturer instructions and applicable codes. Evergreen Off-Grid, LLC assumes no liability for design choices, installation errors, or damages arising from the use of this tool.