Off-Grid Load Calculation Worksheet

Off-Grid AC & DC Electrical Load Worksheet Button

Start by finding how many watts each appliance will consume. Do not add appliances that should be propane-fueled, such as cooktops, hot water heaters and electric heat. Then multiply rated wattage of each appliance by the number of hours per day, on average, that appliance runs. This gives the total watt-hours per day for each light or appliance. Do this for each and every appliance. The total for all appliance loads is the total watt-hours needed each day.

Figures below show some appliances commonly used in independent solar homes. Substitute your own daily hours for each and add other appliances not listed. Refrigerators come on and off on demand by thermostat, so running time per day is not known. A KILL-A-WATT meter will accurately test watt-hours used per day for any AC appliance up to 1875 watts.

Off Grid Load Examples

ApplianceWattsRun Time (Hr/Day)Watt-Hours/Day
10CF Freezer, standard1000
12/24V NovaKool 4CF (w/added insulation)300
32″ LCD TV1403420
Ceiling Fan, 12/24V DC5-20630-120
Ceiling Fan, AC606360
CF bulbs, equal to 15 watts15460
Clothes Washer7003/4525
Coffee Maker3001300
Food processor2001/2010
Laser Printer, in operation901/423
LED bulbs, equal to 5 watts5420
Microwave oven12601/4315
Refrigerator/Freezer (Energy Star)1000
Satellite receiver20360
Small 4CF Apartment Fridge945
Vacuum Cleaner5501/4138
Well pump 120V AC (100 gal/day)1001/3350
Well pump DC (100 gal/day)1001100
Window Air Conditioner66064000

Use the tables below to determine the total energy in watt-hours per day used by all the AC and DC loads in your system or download the PDF above.

1. List all DC loads in the table below and calculate the total watt-hours per day.

Description of DC LoadsWattsXHours/dayEquals =Watt-hours/day

2. List all AC loads in the table below and calculate the total watt-hours per day.

Description of AC LoadsWattsXHours/dayEquals =Watt-hours/day

3. Add DC & AC totals together to get TOTAL WATT-HOURS PER DAY.

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