List your appliances and find out exactly how much power you use per day.
Add all the appliances you plan to run off-grid. We'll calculate your total daily energy needs.
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List every appliance you plan to run, note each one's wattage, then multiply watts by quantity to get total watts. Multiply those watts by the hours you run each appliance per day to get watt-hours (Wh) per day. Adding up every appliance gives your total daily electrical load, which is the number you size your off-grid battery bank and solar array around.
Running watts (also called rated watts) is the steady power an appliance draws while operating. Surge watts is the brief spike, often 2-3x running watts, that motors and compressors demand at startup, such as a fridge, well pump, or air conditioner. This load calculator adds up running watts, but you must size your inverter to handle the largest surge on top of your total running load.
A standard refrigerator draws roughly 100-200 running watts but cycles on and off, so it uses about 1-2 kWh per day. An LED light bulb uses only 8-15 watts each, so ten lights run around 100-150 watts total. Laptops use about 45 watts, phone chargers 5-15 watts, and a microwave 1000-1200 watts. Use the appliance presets above to total your own numbers.
You need enough to cover your total running watts plus the biggest appliance surge for the inverter, and enough daily watt-hours from batteries and solar to power everything between charges. Add every appliance's watts and run-hours here to find your total watts and watt-hours per day, then size your inverter to the total watts and your battery bank to the daily watt-hours.
Bugs, confusing bits, or ideas — all welcome. Thank you!
