Off-Grid Load Calculator (Daily Watt-Hours & Array Size)
Add up every appliance's watts, run-hours, and quantity into a total daily watt-hour load, then get a suggested solar array size to replace it.
array = 1.8 kWh ÷ (4.5 × 0.8) = 0.5 kW
How it works
Every off-grid design starts with one honest number: how many watt-hours you burn in a day. This worksheet builds it appliance by appliance. For each item you enter its running watts, how many hours a day it runs, and how many of them you have. Watts times hours times quantity gives that appliance's daily watt-hours, and the tool sums every row into a total. Add or remove rows until the list matches how you actually live.
That daily total drives the rest of the system. Divide by 1,000 and you have your daily kWh, the figure the battery-bank and inverter tools ask for. The worksheet also suggests a solar array size using the standard identity: array kW equals daily kWh divided by your local peak sun-hours times a derate factor. Peak sun-hours run from about 3.5 in cloudy regions to 6 in the desert Southwest, and the 0.8 derate trims roughly 20% for inverter, wiring, and temperature losses.
Be honest and slightly generous. Phantom standby draws, a refrigerator's real duty cycle, and seasonal swings all push the true number up, so it is safer to overestimate a load than to run out of power on the fifth cloudy day.
LED lights 12 W × 5 h × 5 = 300 Wh
TV 100 W × 3 h × 1 = 300 Wh
total = 1,800 Wh/day (1.8 kWh)
array = 1.8 kWh ÷ (4.5 sun-hours × 0.8) = 0.5 kW