Draw four columns on a regular piece of paper if you are not using spreadsheet paper.
List all items that will use AC and DC electricity in column 1.
List all AC watts that appliances draw in column 2. Use the rating listed on the label. You power AC appliances with DC batteries through an inverter, so any DC amps will have to be converted to AC watts. To get this number, multiply the number of DC amps by 12 to get wattage.
List how many hours in a 24-hour period you will use each item in column 3. Make sure you list every item separately.
Multiply column 2 by column 3 to get watt hours for each appliance and put the totals in column 4. Add together all the numbers in column 4 for the total watt hours.
Determine how many solar panels you will need. Solar power panels are rated by how many watts per hour they provide. Assume your panels produce 100 watts an hour. If you average four hours of sunlight a day, each panel will produce 400 watts a day. Therefore, if you use 1,125 watts of power daily, you will need three panels (400 x 3 = 1,200 watts).
