Determining Your Home Solar Power Needs - Part 2: Calculate in Simple Steps
Calculating the basic solar power energy requirements for your home involves a few simple steps. Here's a guide to help you with the calculations:
Determine Your Average Daily Energy Consumption:
Review your utility bills to find your average monthly kilowatt-hour (kWh) usage. Divide this number by the number of days in the billing period to get your average daily energy consumption. For example, if your average monthly usage is 600 kWh and the billing period is 30 days, your average daily consumption would be 20 kWh (600 kWh / 30 days = 20 kWh/day).
Assess Sunlight Availability:
Consider the amount of sunlight your location receives. Different regions have varying levels of solar irradiation, which is a measure of the amount of solar energy available per square meter. You can find solar irradiation maps or consult local solar resources to estimate the average sunlight hours per day for your area.
Account for System Efficiency:
Solar panels have an efficiency rating, which represents how effectively they convert sunlight into usable electricity. Typical residential solar panels have efficiencies ranging from 15% to 20%. To account for system inefficiencies (such as shading or dirt on panels) and losses in energy conversion, multiply your average daily consumption by a factor between 1.2 and 1.5. For example, if your average daily consumption is 20 kWh, multiplying it by 1.3 would give you an estimate of 26 kWh/day.
Calculate Required Solar System Size:
To determine the solar system size needed, divide your adjusted average daily consumption (step 3) by the average sunlight hours per day (step 2). This will give you an estimate of the system capacity in kilowatts (kW). For example, if your adjusted average daily consumption is 26 kWh/day and your location receives an average of 5 hours of sunlight per day, you would need a solar system capacity of approximately 5.2 kW (26 kWh/day ÷ 5 hours = 5.2 kW).
Consider Available Roof Space:
Assess the available roof space for solar panel installation. The size and orientation of your roof will impact the number of panels you can install. On average, a standard-sized solar panel measures around 1.6 meters by 1 meter, with an area of 1.6 square meters. Divide your required system capacity (step 4) by the typical panel size to estimate the number of panels needed. For example, if your required system capacity is 5.2 kW and each panel has a capacity of 300 watts (0.3 kW), you would need approximately 17 panels (5.2 kW ÷ 0.3 kW = 17.3 panels).
