How Many Solar Panels Do I Need?


When we sit down with San Diego homeowners and ask them about their solar needs one of their first questions is “how many solar panels do I need?” While we wish we could give you a blanket answer, the truth is there are many factors that go into the number of solar panels we install on your roof.

What Are you Hoping to Get out of Solar?

How Many Solar Panels Do I Need will depend on what you want out of solar.

Every person, every household, and every home are unique. It only makes sense that there is no set specific number of solar panels for any home.

Some homes want to use solar for all their electricity while others only want solar for their water heater. It all depends on your wants and needs. However, if you’re looking to get 100% of your electricity through solar, the first thing you should do is grab your utility bill.

Important Factors to Consider

How Many Solar Panels Do I Need? It depends on where you home is.

There are a few important factors to determine when it comes to the number of solar panels you need for your home. We already told you to grab your utility bill, this should tell you how much energy your home uses.

The other things you’ll want to keep in mind are:

  • How much sun your is in your area. – Luckily, we’re in San Diego! The amount of sun we see on a normal day affects the number of panels you need. Someone in San Diego will need fewer solar panels than someone in New Jersey or Illinois.
  • How Much Wattage is in the Panel – The wattage will determine how much energy the solar panels produce. Panels with a lower wattage are generally more affordable, but not as effective.

Calculate How Many Solar Panels Do I Need

Now it’s time to do some math, get your energy bill and a calculator ready. The formula is relatively simple but needs a little explaining.

Now look at your bill, there should be a number of kWh used. This is how the electric company determines the cost of your bill. They multiply that number by the cost of electricity and that’s your monthly bill total.

The next number you need is the number of peak sun hours your home gets. When you talk to a solar expert, they’ll be able to give you a better number based on your exact location. For now, we found an average for the San Diego area. It’s 5.7 hours of sunlight per day, which averages around 171 hours of sunlight per month.

Now divide your monthly kWh by 171. Next, multiply the number by 1,000. For example, your equation should look like this: (kWh/171) * 1,000.

Let’s use the example of 700 kWh per month. The equation is 532/171 = 4. Next multiply: 4 * 1,000 = 4,000. This means you would a solar system around 4 kW.

Calculate How Many Solar Panels You Need

The next step is to find your wattage number. Now that we’ve determined we need 4 kW to run our hypothetical home, we multiply 4 by 1,000. Which gives us 4,000.

The average solar panel has about 250 watts. So, divide 4,000 by 250. That gives us 16, which is the number of panels you would need for your home.

Once again, these numbers are all hypothetical and the true number of solar panels you need depends on your monthly utility bill, where your home is located, and how much you actually want to get out of your solar panels.

Don’t Rely on the Size of Your Home

We’re gong to leave you with one last piece of parting wisdom. Don’t rely on the size of your home to calculate the number of solar panels you think you need.

We see very large homes with small utility bills and tiny homes that have sky-high bills. It all depends on your electric usage and lifestyle choices.

If you have any questions about solar for your San Diego home, don’t hesitate to give us a call.