Solar System Sizing Calculator

Flip on everything your system needs to run — including the homestead loads other calculators forget, like egg incubators, brooder lamps, aquariums, and heated waterers. Set your sun hours and autonomy, and get a complete spec: array watts, battery bank, inverter, and MPPT controller.

SOLAR SIZING LAB

Off-Grid System Calculator

Your Conditions

Peak Sun Hours / Day4.5
Worst-month guide: Pacific NW winter 2.5–3 · Northeast 3.5–4 · Midwest 4–4.5 · Southwest 5.5–6.5. Size for your worst month, not your best.
Days of Battery Autonomy
1 day
2 days
3 days
How long your batteries carry the load with zero sun (storms, snow cover).
Battery Chemistry
LiFePO4
AGM / Lead-Acid
LiFePO4: ~90% usable capacity, 4,000+ cycles. AGM: ~50% usable, cheaper upfront.
01kW 2kW3kW4kW+
Daily Load0 Wh
Solar Array
Battery Bank
Inverter (Pure Sine)
MPPT Controller

Recommended System

Wattages are typical average draws — verify against your equipment nameplates. Array sizing includes a 30% system-loss factor (wiring, controller, temperature, dust). Duty-cycled appliances like fridges use average draw, not compressor peak.

How this calculator works

Each appliance contributes its average watts × hours per day × quantity to your daily load. Duty-cycled appliances like refrigerators and incubators use realistic average draw, not compressor peak. Array sizing applies a 30% loss factor (wiring, controller efficiency, temperature, dust) against your worst-month sun hours. Battery sizing divides your autonomy requirement by usable depth of discharge — ~90% for LiFePO4, ~50% for AGM. The inverter figure covers your largest surge load plus everything running around the clock, with 20% margin, and the MPPT rating adds 25% headroom over array current at your recommended system voltage.

Why we include the weird stuff

Off-grid solar isn’t just cabin lights and a fridge. If you hatch chicks, keep reptiles or fish, heat poultry water through winter, or run a greenhouse, those are the loads where an undersized system actually hurts — they’re continuity-critical and mostly invisible to generic calculators. That’s why the Homestead & Critters panel exists, and why the calculator pushes your autonomy up when it sees hatching or tank loads on the line.

Next steps

Take your spec to our full sizing guide for the deeper walkthrough, then match components: complete kits if you want everything pre-matched, or build custom from panels, battery banks, and charge controllers. Mounting questions? Hardware guides here.