How Many Solar Panels Do I Need? Find Out In Six Easy Steps

I get it – you want to live more sustainably and do your part to be energy efficient and reduce your carbon footprint. Don’t we all. But where to start? Converting your home to solar power can feel overwhelming, but never fear: I’ll walk you through everything you need to know to harness the power of solar panels for your home. From calculating your current energy use to the smartest process for shopping for solar panels, I’ll outline everything you need. Let’s get started

Here are a few general steps you need to take to determine how many solar panels are best for your home and energy needs. I’ve outlined them for you here:

1. Calculate how much power you use

2. Figure out how much power solar panels can provide for your home

3. Decide how much power usage you want to offset with solar

4. Verify your roof size

5. Use a solar calculator

6. Shop around

Now I’ll give you a closer look at each one of the steps in the process:

Calculate how much power you use

First, you need to do a little bit of detective work to find out how much energy your household is currently using. You can get a good idea of your energy usage by simply looking at your current power bill. Chances are, it outlines monthly kilowatt hour usage on every monthly bill. And fun fact: some power bills may even report a running tally of your kilowatt hour usage to date.

Once you know how much power you use in a typical month, you can decide how much of that usage you’d like to convert to solar power. Here’s what’s important: knowing your goals. Most people who install solar panels are looking both to save on their energy costs and to reduce their overall carbon footprint.

Figure out how much power solar panels can provide for your home

Different areas of the world benefit from solar power at different levels, and this will determine how much power your solar panels are able to produce. Of course, the more sunlight that hits your roof on a regular basis, the more you’re going to be able to capitalize on solar energy. The southwest region of the United States gets the most sunlight in general, and homes that face south are likely to benefit from sunlight more so than those who face other directions. Trees around your home that provide shade to your roof’s surface area also can affect how much you’re able to benefit from solar.

In addition, solar panels come with a wide variety of kilowatt capabilities. And the main thing to keep in mind is this: the higher quality panels you invest in on the front end, the fewer of them you’ll need to use. If you’re working with a reputable solar installation partner, they can help you determine which size and setup is best for you.

If you want to get super precise with it, I’d recommend the following method: take your hourly home energy usage and multiply it by 1000. This will convert the number from kilowatt hours to watts. Then divide that number by the number of peak sunlight hours for your geographic area – if you’re not sure, you can always check with the Renewable Resource Data Center. The Center compiles data about sunlight hours for all 50 states and many major cities.

Once you have that number, you’ll know how many watts of power your solar panels will need to generate per hour to fully offset your current energy costs. At that point, you can divide that number by the wattage of the panels you’re considering, which will tell you how many panels you should install. Just for reference, most panels used for residential installation run between 150 and 370 watts per panel.

Decide how much power usage you want to offset with solar

Maybe you’re looking to make a radical change and you want to offset 100 percent of your energy usage with solar. Or maybe you just want to give it a try and shave about 25 percent or so off your energy use. Here’s the deal: there’s no wrong way to get started with solar energy. But knowing how much energy you want to divert to solar will help you decide how many panels you should install.

And something else to keep in mind: solar panels don’t always work at full capacity. Weather conditions have a huge influence over your solar panels’ capability, so I’d recommend adding up to a 25-percent padding on top of what you think you’ll need to meet your goals – just in case.

Verify your roof size

It doesn’t matter how many solar panels you’ve calculated that you need if your roof doesn’t have the space to hold them. Before you make a final decision about installing solar panels, make sure you measure and verify the amount of your available roof space. If you have a small or oddly shaped roof, you may need to invest in smaller, higher wattage solar panels to get to the energy output you need. But if you have a good deal of usable space on your roof, you can go with less premium quality solar panels and simply use more of them to reach your energy needs. Again, this is where a good partner who is an expert in solar panel installation can help you maximize your investment.

Use a solar calculator

Here’s the deal: once you’ve followed all the steps listed above, you also can verify your work by using an online solar calculator. These tools aggregate data from weather stations and other GIS sources from around the world, so they’re great at checking the accuracy of your local calculations. In most cases, all you have to do is plug in your address and your average monthly energy bill amount – and voila!, you’ll get an estimate of the right number of solar panels for you.

Shop around

Installing a solar power system is a big deal and a major investment in your home. So pro tip: take your time doing your research and getting quotes. Don’t just go with the first solar provider you find. Try to get at least three quotes – some estimates show that when you shop around, you can expect to save up to 10 percent on your solar installation costs. And according to the U.S. Department of Energy, you’re usually better off going with a smaller provider than many of the larger installers. In fact, large installers may charge between $2000 and $5000 more than their smaller, independent counterparts, for the same work.

And here’s a pro tip: while price is important, don’t let it be the only factor you consider when choosing your solar panels. They have a pretty long life span – sometimes as much as 30 years – so it’s worth it to talk with experts and make a good investment, rather than simply choosing the least expensive option.

FAQs

How many solar panels are needed to run a house?

Here’s the bottom line: that all depends on the size of the house and your household’s average energy consumption. Before you make a decision on how many solar panels you want to try, make sure to go through the process I’ve outlined above to get a reliable estimate for how much power you typically use and how much can be offset through installing solar panels. When you work with a trusted, knowledgeable and reputable solar panel installer, they can also help you figure out how many solar panels you’ll ultimately need.

How many solar panels do I need for 1000 kWh per month?

Great question. The U.S. Energy Information Administration reports that the average American household uses around 914 kilowatt hours of electricity per month, or just under 11,000 kilowatt hours in a given year. The biggest users of energy are typically heating and cooling systems – or swimming pools. Depending on the size and location of your home, plus the kilowatt hour capability of your solar power system, it can take anywhere from 14 to 36 panels to generate 1000 kilowatt hours of energy per month. And here’s a good rule of thumb: the higher quality solar panels you invest in, the fewer of them you’ll need.

How many solar panels do I need for a 2000 square foot house?

How much energy are you trying to generate? That’s a key part of the equation here. If you’re looking for a general guideline, the U.S. Energy Information Administration states that for houses between 2000 and 2499 square feet, general energy usage is around 967 kilowatt hours per month. With a south-facing roof, you’d need between 16 and 25 premium solar panels to generate the same amount of energy for your home – that’s for drawing all of your energy needs from solar energy. And “premium” means the highest-efficiency solar panels available, which can generate about 400 watts. If you decide to go with budget panels rather than the premium version, you’ll need between 24 and 38 solar panels to get the job done. I know that’s a big range, but a range is all I can really give you without knowing the details of weather conditions where you live – or in other words, how much power you can expect to harness form direct sunlight on your roof and its solar panels.

How many solar panels does it take to make 3000 kWh a month?

Here’s the bottom line: the number of solar panels you need depends on a lot of different factors – like how much sunlight your panels are likely to be exposed to during the day, along with the quality of the solar panels you’re using. So if you want to make 3000 kilowatts of energy per month, and your house gets about five hours of direct sunlight per day, you can divide that 3000 by 5 times 30, or the rough number of days in a month, which means you’re dividing 3000 by 150, which gives you 20. So you’re looking for a 20 kilowatt solar panel system.

But you’re not yet finished: now you take that number, multiply it by 1000 and then divide it by the wattage of the panels you’re considering. For example, if you’re thinking of installing 150-watt panels, you’ll divide by 150, which gives you 20,000/150, or 133.33. In that case, you’d probably want to install at least 134 panels, plus perhaps a few extra to account for days when the weather just doesn’t cooperate. If you went up to 200-watt panels, your number would change to 100 panels. The higher the wattage of your solar panels, the fewer of them you’ll need to install.

Conclusion

So the ultimate answer to, “how many solar panels do I need” is that it really depends. I can’t give you one magical answer. While the average American home can fully offset its energy use by installing anywhere from 14 to 38 solar panels, the exact number of panels that’s right for your home will depend on your overall power usage, the size of your home and the amount of energy use you’re trying to offset – plus the amount of direct sunlight you get.

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