Many people purchase solar panels to offset their electricity bills completely. As such, a common question is how many solar panels they need to power their home entirely. The answer depends on electricity usage, sun exposure, and solar panel rating.
Electricity usage is the amount of power a consumer uses every year. A person can know how much electricity they use by checking their monthly electricity bill. Because consumption varies by month, it is better to get the bills from a full year and find the average rather than rely on one month’s bill.
Sun exposure is the number of hours of peak sunlight a home gets. Peak sunlight is when the sun’s intensity is about 1,000 watts (1,000W) per square meter. The daily US average for peak sun hours varies from over 5.75 hours in the southwest to under four hours in the north.
Finally, solar panel wattage is the power rating of the solar panel. It varies from 250W to 450W, but the most common rating requested is 400W.
The formula for calculating the number of panels a home needs is electricity consumption/sun exposure/solar panel wattage. Assume a home has a monthly power expense of 800-kilowatt hours (800,000-watt hours), 4 hours of daily peak sun exposure (120 hours in a 30-day month), and solar panels rated 400W. The owner will need 17 solar panels to fully meet their energy needs (800,000/120/400=16.66 panels).
