How Many Solar Panels Do You Need?

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Solar panel systems for homes are decreasing in price and increasing in popularity. Many homeowners are starting to see the advantages of solar power, and you may have seen quite a few systems being installed in your neighborhood.

If you have made the decision to move forward with your solar ambitions, but are unsure about the size of the system you’re going to need, this article is for you. In the following few paragraphs, we’re going to talk about how to size your solar system properly, so keep on reading.

Figuring out the size of your solar energy system begins with a straightforward question: ‘How many solar panels do I need?’ Because most people would like to produce enough energy so that they are entirely independent of their utility company, eliminating their bill for electricity, the first step is to determine how much power is consumed by your household. It boils down to calculating the number of kilowatt-hours of energy you require and getting the right amount of appropriately-sized solar panels to power your home.

How Many Solar Panels to Power a House?

construction worker and lady looking at house plansFirst, we could talk about some general solar energy facts and numbers. The average home in the US requires anywhere between 28 and 34 solar panels to become completely independent from the power grid. Also, panel performance and geographical location are important factors that you need to consider when determining the number of panels your house needs. Hence, things are not quite so simple to calculate.

The average American household consumes roughly ten thousand kWh per year, which is how we reached the average number of solar panels required to be between 28 and 34 250W panels depending on roof size and location.

If you’re still wondering how we came up with those numbers, the breakdown is relatively straightforward. When you want to know how much power your house needs to operate daily, start by taking a look at the number of watt-hours used every day. To do this, simply look at your electric bill, which will most likely provide you with a yearly kWh consumption and divide the number by 365 to get your daily use.

For some perspective, you should know that one kWh equals a thousand watts of power used within one hour. This means that if you have ten lights in your home, all using 60W bulbs, having all the lights on for one hour will add up to 600Wh or 0.6kWh of electricity.

Location is also significant, with the highest and lowest solar panel production ratios differing by a considerable margin depending on where you live. The amount of power your panels can produce depends most of all on how much sunlight they will receive.

If you plan on mounting them on your roof, this means the amount of sunlight received by your roof on average. This amount depends not only on where you live but also on the season you are currently in. California is not the same as Maine in terms of annual sunny days, but that doesn’t mean you can’t produce enough power to cover your needs in both states; you’ll just need a more extensive system in Maine than you would in California.

residential solar panels on the roof

How Much Solar Do I Need?

To begin answering that question, we’re going to start by telling you the most important thing you need to remember when designing any solar system. Every component you buy and every decision you make regarding your solar set-up revolves around the idea of knowing how much power you need to power the appliances that you want.

Therefore, the size of your solar array, a.k.a. the number of solar panels that you need solely depends on how much energy you use daily. You should size your battery bank depending on how long you want your energy storage to last. The charge controller needs to be able to manage the energy between your battery banks and solar panels correctly. At the same time, your inverter will depend on the type of appliances you want to power. Even the sizes of fuses and wires depend on how much energy is going to be flowing through.

Solar Panel Size Calculation

solar panel calculationAt this point, you’re probably asking yourself how to size your system and how to calculate all the stuff that we mentioned above. Lucky for you, we’re here to tell you exactly how to do that.

First, you need to list out every appliance that you intend to power using your solar system. We know this isn’t the most exhilarating work you’ll ever do, but you need to go to every appliance in your home and find their power consumption rating. This label can either be imprinted on the charger or on a sticker on the device itself.

What you’re looking for is the output rating for the appliance. This can either be listed in volts and milliamps or amps. Ultimately you are concerned with the wattage of the device. If it already says the number of watts on the label, simply go ahead and write that number down, but most devices will use volt and amp labeling. Thankfully, there is a simple formula you can use to convert those values into your output wattage. The equation is this – W (Watts) = V (Volts) x A (Amps). If you have milliamps (mA) as your variable, all you need to do is divide that number by 1000 do get the value in amps, so, for example, 500mA = 0.5A.

If you can’t seem to find the power consumption rating label, look instead for the model number of your device. Either Google this number, or find a similar device online so that you could get an idea of how much power that will draw.

Once you list out every appliance that you intend to use with your solar power system, along with the corresponding output wattage, you’ll want to ask yourself how long you’re going to use each appliance daily. For this number, you’re going to use hours as your variable. So, if you’re going to use a device for half an hour or 15 minutes each day, write it down as 0.5 and 0.25 hours, respectively.

After you have written down how much time you plan to use your devices each day, you’re going to want to multiply the output wattage by the hours per day that you intend to use each device.

how much power for solar panels imageFor example, take your 15w phone charger and multiply that with the 2 hours that you intend to use it per day. That gives you 30 watt-hours (Wh). Let’s also say that your partner has the same charger and wants to use it for the same amount, all you need to do is multiply that final amount by two, and you get your total number of Wh spent on charging your phones per day, which is 60.

Next, repeat this process for each appliance that you have on your list, and at the end, each machine should have a corresponding Wh figure. Finally, add all those watt-hour numbers and write down the total Watt Hours/Day spent in your household.

Now that you have this number, all you need to do is divide it by the wattage of your desired solar panels, and you’ll have the magic number. There are many calculators online you can use to give you an exact measurement, taking into account the temperature your batteries will encounter as well as other factors, but this is the simplest explanation of the process.


There is no one-size-fits-all when it comes to solar panel systems. The number of solar panels in a set-up differs from one system to another. A significant factor determining how many solar panels you need is your electric bill, and most people aim to save the most money by installing enough panels to cover all of their electricity needs.

Your location is another factor. Depending on their geographic location, solar panels produce different amounts of electricity. For example, you’ll generate more power in a year if you install solar panels in Florida than if you install the same number of panels in Alaska, simply because Florida gets more sunshine.

Your solar panels should ideally be installed facing south in an area with no shade. However, that may not always be possible. Panels facing other directions will still produce electricity, although not as much as if they face the south. Therefore, you’ll probably have to install additional panels to achieve the same results.

In the end, some solar panels are more efficient than others. Highly efficient solar panels generate more energy, but they are also more expensive, which means you will not be able to install as many of them. If you have any other concerns about how many solar panels to run a house and how to install them be sure to read our other blogs.

If you choose to consult with a solar installation company, their professional team will take all these factors into account when they custom design a solar panels system for your home or business.