You might have gotten a solar quote and wondered if you really need that many panels.

It's a good question, so we're here to help!

The Steps

You need to consider the following to calculate your solar panel needs:

1. Average monthly electricity usage - You get this from your power bill by summing kWh usage from the last 12 months and then dividing by 12.
2. Average monthly hours of sunlight - Lookup online what the average hours of sunlight is in your area each day (averaged across the entire year, not just one month or season), and multiply that by 30 to get a monthly number.
3. Panel size - Your average solar panel produces about 400 watts (0.4 kW) of energy in direct sunlight.
4. Make the calculation - Average monthly electricity usage (kWh) / (Average monthly hours of sunlight * Panel size (kW))

For example, if your average monthly electricity usage is 1,250 kWh, you have an average of 240 hours of sunlight each month, and you're using 0.4 kW panels, then you would need about 13 panels! (1,250 / (240 * 0.4))

Other Factors to Consider

There are several other factors you need to be careful of:

1. Is there shade from trees on your roof?
2. Are you using microinverters or string inverters?
3. How much variability in sunlight is there month to month or season to season?
4. What does your net metering plan look like? (it might be worth it to oversize your system slightly)

Need Help?

Still confused or unsure how to calculate this for yourself?

Fill out the form and one of our helpful energy consultants can walk you through it!