The number of solar panels you need is one of the key factors to get right to ensure your solar system is able to replace your electric bill and save your family. Learn about the other five factors we consider to understand the economics of solar.
There are three factors to consider in order to determine how many solar panels you need to power your house: your energy usage, available roof space, and budget.
Your Energy Usage
The most important factor in determining how many solar panels you need is the amount of energy that your house uses.
Determining Your Energy Usage
A primary goal of installing solar is to achieve net-zero, which means your solar panels produce as much energy as your home uses in a year. You can determine how much energy your home uses in a year by totaling your energy usage from each month. Your monthly energy usage is reported in your utility statements in kilowatt hours (kWh).
If you don’t have monthly utility statements for the past year, a solar provider can work with you to create the best estimate possible based on the available information.
Adding New Energy-Hungry Appliances?
If you know you plan to add a new electricity-hungry appliance like a pool pump, you can learn approximately how many additional panels will be needed to run it by reading “How Many Solar Panels Does It Take to Run a Fridge?
Sizing Your Solar Array “Just Right”
It is not recommended to install a photovoltaic solar system which will produce more energy in a year than you use.
This is because any excess energy it produces is sold back to the utility at a far lower rate than the utility charges customers. You will not be able to make significant money back selling this energy. You should size your solar system to produce just as much electricity as you expect to use- no more, no less.
Your Roof Space
The second factor which influences how many solar panels you need is your available roof space.
A solar provider’s engineers will determine the number of panels your roof can safely fit.
The best roof space is on the southern face, followed by the western face and the eastern face. The ideal roof is clear of shading and obstructions like large trees, vents, or air conditioners.
Your Solar Project Budget
In addition to designing your system to produce the same amount of electricity that you consume over a year, you want to size your system so its payments exactly replace your current monthly electric bill.
Often, it is possible to create a plan which results in lower monthly bills. Your bill with solar should never be higher than it was before going solar. Sizing your system like this makes your financial transition to solar as easy as possible.
Over time, your monthly payment with solar will become lower relative to what your electric bill would be, since electricity costs increase over time while your solar payments will remain constant.
So, How Many Solar Panels Do I Need?
The number of solar panels you need can be roughly approximated by dividing your average monthly kWh usage by thirty. This is assuming that a solar panel will produce 1 kWh per day, which is a rough approximation based on a panel producing 250 watts at peak production and with four hours of peak sun per day.
The actual number of panels you need will vary based on your roof’s specifications, solar exposure, local climate conditions, and the hardware that you are using.