Quick Answer
Determine the solar array size by calculating the total wattage required by appliances, accounting for peak sun hours, and considering a 25% buffer for energy storage and efficiency losses.
Calculating Appliance Wattage
To determine the solar array size, first, list and calculate the wattage of each appliance you want to power. For example, a 12V refrigerator might be 60W, a 12V LED TV might be 20W, and a 12V fan might be 10W. If you have multiple appliances, sum their wattage requirements. Next, consider the number of hours you’ll use each appliance daily.
Accounting for Peak Sun Hours
Peak Sun Hours (PSH) is the amount of sunlight your solar array receives daily. In the northern USA, average PSH varies from 4 to 6 hours. To determine your PSH, use online calculators or consult with a solar professional. Multiply the total wattage of your appliances by the number of hours you’ll use each one and then by the PSH. For example, if your appliances require 100W for 8 hours a day in a location with 5 PSH, your daily energy demand would be 100W * 8h = 800Wh * 5PSH = 4000Wh.
Sizing the Solar Array
Add a 25% buffer to your daily energy demand to account for efficiency losses and energy storage. For example, if your daily energy demand is 4000Wh, add 25% to get 5000Wh. Now, divide the total daily energy demand by the PSH to get the required solar array size in watts. Using the previous example, 5000Wh / 5PSH = 1000W. Round up to the nearest panel size to ensure adequate power generation, and consider the number and wattage of your panels to fit your space and budget.
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