How to calculate solar power?

One of the most important steps in planning a solar project is to determine how many panels you will need to power your home. The number of panels is the key factor in figuring out how expensive it will be to outfit your home to use solar power. This calculation will require you to have an electric bill for December that includes a summary of your electricity usage for the other months of the year, or all of your bills for the year.

Step 1

Calculate your average electricity use per day in watts using your electric bill for December. Your electric bill should have your usage for each month on the bill, add the total kilowatt hours you used for the year and divide by 365 to get your average electricity use. Multiply that result by a thousand to get the result in watts. Your electric company may already provide this number on the bill.

For example, say that you used your electricity usage for each of the 12 months was 340, 325, 330, 345, 340, 320, 315, 325, 330, 335, 330 and 345. Adding these numbers together yields 3,980 kWh. Then divide this figure by 365 days in a year: 3,980 / 365 = 10.904 kWh per day. Multiply by 1,000 to convert this to watts: 10.904 * 1,000 = 10,904 watts per day.