Calculator · cold, mild or hot
Load, battery & solar sizing
From a Maine winter to a desert summer. List what you run, pick your climate and sun, and see honestly how big the system gets.
| Appliance | Watts | Hours/day | Qty | Wh/day | Remove |
|---|
Heating/cooling rows are separate examples, not a recommendation to run both. Remove any alternative you do not use. Wattages are typical examples for planning. Check your unit's label or spec sheet. Heat-pump draw varies a lot with outdoor temperature.
Daily energy
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Planning battery capacity
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Solar array
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Inverter screening range
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Sum of listed running watts to 1.5× illustration only. Check actual startup surge, voltage and simultaneity; this is not a safe sizing rule.Without heating/cooling rows
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Same days and sun, for comparisonCaveats: This is a planning estimate, not an engineering design. Battery size assumes 80% usable depth of discharge, plus a climate derate (cold: −20% effective capacity; hot: −5%). Solar assumes ~75% system efficiency, with an extra ~12% loss for panel heat in hot climates; snow cover is not modeled. Actual starting surges vary widely and can exceed the screening range. Battery calculations include a 90% illustrative delivery-efficiency factor; solar includes a separate 75% generation allowance. These are rough planning factors, not a detailed energy model. Follow the exact battery manual’s temperature limits; many LiFePO4 batteries restrict charging at or below freezing even if discharge is permitted. Heating consumes energy not included here. Combustion heat needs correct, approved installation, venting and CO alarms. Never use a portable unvented heater as an overnight heat plan. Have a licensed electrician do permanent wiring.