Determine the amount of electricity you need
The size of solar panels you need will ultimately depend on the amount of electricity you use. Typically, the amount of electricity a solar panel produces is proportionate to its size. To determine which size suits your needs, you will need to calculate the average amount of electricity you use on a daily basis, then convert it into the voltage a particular size of panel produces.
Firstly, you should add up all your electricity bills for the past one year and find the average. Find the voltage you use monthly for the past one year, and then average them. It’s easy to find the voltage as it is always indicated in your electricity bill.
Rooftop space available
The next thing is to determine whether the space available on your roof can accommodate a solar panel. Actually, it doesn’t always have to be a rooftop space. Nowadays, many people build support structures if the design of the roof doesn’t offer enough space for a solar panel.
A normal solar panel measures about 3 feet by 5 feet. We assume that you have about 225 square feet of space on your roof. Divide 225 by 15 and you now know that you could mount up to 15 solar panels on your roof.
How efficient are the solar panels
You will need to determine the kind of solar panels you want. Typically, the size of a panel (among other factors) will determine the efficiency of electricity production. It will also determine if you need just one panel on the roof or a dozen panels to support your electricity needs.
To get an average of 190 watts from a panel, you will need a panel of 58 inches long and 34 inches wide (these dimensions are the average dimensions of different brands of solar panels available in the market). With the size of your roof and the amount of electricity you need, you can determine if these average measurements of a solar panel works for you. If you need less than 190 watts and have enough space on your roof, you just need a solar panel that is bigger to produce more electricity.
Location of the solar panels
Location is also key. The efficiency of a solar panel is based on the average amount of sunlight it is exposed to daily. If you live in an areas with abundant sunshine, then you will not need a large solar panel.
However, if you live in a cold area where it is overcast most of the time, you will need solar panels as huge as possible to get the electricity you need. The cost of buying and maintaining the solar panel are also important. Its cost will depend on the size you choose which usually varies from brand to brand. Obviously, the smaller the solar panel, the more affordable it is.