# How Many Solar Panels Do I Need?- Why Do You Need My Utility Bill If I Just Want a Quote On Solar Panels?

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1. ```Once someone becomes interested in going solar, they first want to know, "How many solar panels do I need?" This question seems so cut and dry. It looks like it should be easy to calculate. So why is it that if I call five solar companies, none of them will give me any numbers over the phone? The answer is simple yet complicated. Imagine if someone asked you how much gas it would take to drive to Oregon. You would first run some quick math in your head, knowing the distance and then multiplying the miles per gallon your car will need to burn. For example, maybe you get 12 miles to the gallon, and it is 675 miles to get to Oregon. You would calculate 675 miles total, divided by 12 miles to the gallon, meaning you would need 56.25 gallons of gas to drive to Oregon. But if you were missing either of those numbers, you could not figure out the amount of gas required. There are just too many variables between cars, motors, and freeways.```

Testing the roof slope can help predict the performance of a solar panel on that slope.

Now, let’s try the thought experiment but without the total miles. So we might say 12 miles to the gallon, but what next? Again, we have no way to proceed.
It’s challenging to know what the solar world is. Prospect says,”Here is my house, it’s on ***** race street, How many solar panels do I need?.”
Prospect says, “All your salespeople are the same; I’m not giving you my utility bill because you’re just going to match my current monthly payment and convince me the polar bears are in trouble. All I want to know is, How many solar panels do I need?”
Sizing solar for each home is a math equation. But, of course, every house is different. In addition, there are significant apparent differences, such as shade. For example, shade from a massive tree can make two houses that are otherwise identical utterly different in terms of the size of the solar system needed to power the house at 100%.
Otherwise, minor, subtle differences can make significant differences in cost.
For instance, two similar-sized houses in the same neighborhood have similar annual consumptions. They were both built in the 80s but by different builders. One has a Federal Pacific Electric Panel, and the other two newer homes have a Square D QO Panel. It might be the original unit, or maybe the owner replaced it a decade ago. Either way, these two similar homes will substantially differ in the price of going solar.

Just like all trades work, electrical work requires permits. Permits get pulled from the local building departments and must abide by the most current building codes. Most likely, the building department will call for any Federal Pacific panel to be replaced because they have a terrible reputation for fire hazards. Replacing an MPU adds about \$2,000-\$2,500 to the system’s total price.

These are just two examples of things that can dramatically change the number of panels needed to power each home. But, unfortunately, asking, How many solar panels do I need? It is just never going to be that simple.
We haven’t even begun to address living habits. For example, I like to run the AC all day and all night. It just feels good. On the other hand, my wife is under a heavy blanket, telling me it’s way too cold. This can have a significant effect on consumption.

It’s always wise to get a few quotes and try to understand what you are explicitly getting. Just be sure to ask the right questions.

1. What is the wattage of each panel?
1. Microinverters or string inverters?
1. What is the warranty on the solar panels?
1. Is the labor included in the warranty
1. Do the inverters have the same warranty?
1. Does hail affect solar panels?
If a hail storm breaks the panels, are they under warranty?

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