If you’re going to go solar, you want to do it right. By doing some math, you can figure out how much energy solar panels can produce on your roof and decide which company gives you the best bang for your buck.
Step One
Figure out what your monthly electricity bill is on an average basis. Let’s say that number is $245. Your electric company charges you $12/kWh for electricity, and on average 19.50 a month - as a fixed rate. To convert these numbers and figure out how much the panels would produce at this rate, you’ll subtract $19.50 from $245, coming up with $225.50 leftover. If your electric company charges 12 cents/kWh for electricity, divide $225.50 by .12. This means you’ll need 1,880 kWh per month with your solar panels, and this number is your average electricity usage month-to-month.
Step Two
Now you need to find out how much solar panels will make from different companies and compare. Look at the size of the system (between 6.08 kW and 16.82 kW.) Find out how much electricity can be produced every year for each kW of panels, and choose a size that is right for you. For example’s sake, let’s say that number is 1600. Multiply that by the number of kW in the system size, and you end up with 9,728kWh. (6.08 x 1600).
On top of that, you need to consider that during the production and wiring process, some of the energy is lost before it’s sent to the grid. Around 19% of the energy will be lost during that process - meaning should estimate the number we came up with above by 79% (.79).
Something to keep in mind, this estimate is giving you a rough number for your general area, not your specific roof. To get an idea of your specific roof, you’d need to get a quote.(insert link to our quote system).
Step 3
The next step is to figure out how much you can eliminate from your electricity bill. You’ve got a $245 electricity bill, that when converted to solar energy is 1,880 kWh monthly with a $19.50 fixed rate.
Your first solar quote says their panels will produce 7,685 kWh per year. Monthly, that is 640 per month. Is that anywhere near 80% savings? No. You’d be at 31% savings.
So you get a second quote, for a system that produces 21,260 kWh per year, $212.64 per month - averaging out to 87% savings.
What it comes down to here is the honesty of the salesman and of the company. It’s up to you to do the math and find out what is the best deal for your roof, and compare quotes.
Step 4
Find out which deal is best for you. While the answer is pretty obvious, you should know that the clearest way to go about this is to compare dollars per watt. Approaching these two quotes in this way would look something like this:
Quote 1: $25,000 / 6,080 = $4.11/watt
Quote 2: $49,950 / 16,820 = $2.97/watt
From this approach, you can see how much coverage you’re getting and for how much. Surprisingly, a larger system is giving you a cheaper price for what you’re getting. You should get multiple quotes from multiple companies, and at different solar system sizes. We hope we helped clear up some of the math; now get out there and do some for yourself!