How Many Solar Panels Do I Need?

How to think about scaling a solar system to meet your needs

One of the things that homeowners commonly wonder about when they’re considering going solar is how many solar panels they’ll need to have installed. What’s behind this question is often concern about whether their home has enough “solar potential” to get a good return on investment from going solar.

To figure out the scale of the solar system you will need to achieve your financial and energy generation goals, you first need to understand your own energy needs. When our energy consultants talk with homeowners about whether going solar is right for them, we recommend they find their annual average energy consumption by looking at the electricity usage from their utility bills from the previous 12 months. Then, consider any changes in lifestyle you anticipate in the near future that might impact your energy consumption – such as purchasing an electric vehicle.

Using this information, we can determine the amount of electricity your solar panels will need to generate to meet your energy needs. You should understand that depending on the incentives available in your state, it may make financial sense to continue to buy some of your electricity from your utility rather than to install a solar system that generates 100%+ of your anticipated energy usage.

The next factor to consider is the unique characteristics of your home. Obviously, sun exposure is crucial for generating electricity from solar panels. The directional orientation of your home and shading from trees, hills, or other nearby buildings all impact how much sun your solar panels can soak in and how much energy they’ll be able to produce. The square footage of available space on your roof also determines how many panels can be installed.

Google has created an excellent tool called Project Sunroof that will give you an idea of how much sun exposure the roof of your home gets. You simply type in your address, and get an estimation of the solar energy capacity of your home.

Now that you’ve considered your energy needs and the structural and environmental factors, you can actually answer the question of how many solar panels you need in your residential solar system. Solar panels are classified by the wattage of the electricity they can generate, which is in turn determined by their physical size and the efficiency of their design. If you have limited roof space, then it might be necessary to use a smaller number of higher-wattage panels. On the other hand, if you have abundant roof space to place panels on, then a larger number of cheaper lower-wattage panels might be a smarter buy. Another scenario may be that you have plenty of roof space, but expect to increase your usage in the years to come – perhaps by installing a swimming pool or buying an electric vehicle. In this case, you may opt for higher wattage panels to leave adequate space to add more panels down the road when your usage is higher.

In the end, the actual number of solar panels installed on your home isn’t very important in and of itself. The more pertinent consideration is how much energy do you need to generate, and how much roof space do you have available to use. Still, thinking about this question can be a useful starting point for understanding the factors you need to consider when deciding whether going solar is the right decision for you.

If you’d like to talk in more detail about your home’s solar potential, schedule a no-pressure conversation with one of our energy consultants. To make sure you don’t miss any of our articles on understanding the value of residential solar, follow us on social media.

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