Of all the things you have to figure out when planning a solar power system, the number of panels you’ll need is a big one. Yet, all variables are interrelated and you can’t figure out how many panels you need unless you know some other important information first.

What is my daily power consumption?

You need to calculate how much power, in watts, you use on a daily basis. Your electric bill will be necessary for this. A lot of utilities actually break this down for you in your monthly statements. If you’re not so lucky, there are online tools to help you out.

How much sunlight do I get per day?

Another thing you’ll need to know is the average amount of peak sunlight you get per day. This means yearly average. So don’t think summer hours; many areas get great sun in the summer but you might not see it for what feels like a month in the winter. Be sure to calculate the average…and be conservative. There are online calculators to help you get this exact also.

How many panels do I need?

Once you know your average power consumption and the amount of sunlight you receive each day, you are ready to calculate the number of panels you’ll need. It is easy. First divide the total watts you use each day by the hours of sun you receive. That is the number of watts you need to generate in one hour. Solar panels are rated in watts. For instance, a 200-watt solar panel will produce 200 watts of power each hour of peak sunlight. Therefore, if you need to produce 500 watts of power each hour then you’ll need five 100W solar panels. Note that panel ratings vary, meaning you could choose five 100W panels, ten 50W panels, or just one 500W panel. You get the picture…

Also keep in mind that while some people do get all their power from solar panels, most use solar panels to supply a percentage of their electrical needs. You can always start small and add on later. Think about your energy goals, the amount of money you hope to save each month, and how much you can afford to pay for a system up-front.

A certified, local installer can help you design your solar system, not to mention help you with purchasing, rebates, and installation.

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Posted on October 1st in Solar Electric by Dan.