At an average cost of $20,000 per system, residential solar panels are a sizable investment for most homeowners. If you're thinking about going solar, you'll probably have quite a few questions about it, including how many solar panels you'll need to power your property. 

In general, the average solar system for a home consists of 20-25 panels, but the exact number you'll need will depend on numerous factors, including where you live, how much energy you typically use, and how much power your panels can generate. 

It might seem like a lot to consider, but it's pretty simple when you break it down. Let's look at three key factors that determine how many solar panels you need to power your house, as well as an example of how to calculate the size of your system. 

Average energy usage

Understanding how much electricity you use in an average year, month and day is key to estimating the number of solar panels you need. Energy usage can vary quite a bit, depending on the number of people in your household, as well as how many appliances you have and how often you use them. 

Check last year's energy bills to find out how much electricity you use over the course of all four seasons (hint: it's measured in kilowatt-hours or kWh). Once you have that number, you'll know how much solar power you need to generate to cover your needs. For reference, the average American home uses 10,649 kWh per year. That's just over 29 kWh per day.