How Many Solar Panels Do I Need?

how many solar panels do i need?

So, you have decided to go for eco-friendlier, more sustainable technology to power up your home. Going solar is a wise idea. When you go solar, you will no longer be fully dependent on fossil fuel-sourced grid energy, but you will utilize the sun’s light to collect energy that can be converted to electricity, which can be used to power up your home appliances and electricity-dependent utilities.

Not only will you be able to help the environment by reducing your carbon footprint, but you will also save some money on utility bills. Therefore, it is a win-win decision.

However, admittedly, going solar may not be very cheap. You will spend time, effort, and money (on fees) to get the appropriate permits. You will have to pay for the services of the solar panel installer. Of course, you will have to buy solar panels. This is besides the fact that there are 3 types of solar panels, and you will need to be wise in choosing so that you can make the most out of your solar panel system.

Finally, you must think about the number of solar panels needed to supply the energy that your household requires. This article will discuss the last point further and help you determine the actual quantity you will need to purchase to get your solar panel system set up.

How Many Solar Panels Do I Need to Power a House?

Are you considering, “How many solar panels do you need?” Well, you must know what your household electricity consumption is. This can seem like a lot of work and may even require checking your appliances and their corresponding wattages. But this method can provide you with an accurate estimate of the amount of energy that you will need and the number of panels that you must acquire for roof installation. Of course, your budget plays a huge role in the decision as well.

Also, note that panels have various capacities and sizes. There are 100-watt panels. There are also those between 200 and 300 watts. Depending on your household energy needs, you can determine the number of panels that you will need based on the wattages of each individual panel. This is considering that the number you require will fit on your roof.

The geographic location of your house will also matter as certain locations get more sunlight than others, and it can impact the number of solar panels that you will need. For instance, a typical household located in California will only need a 7-kW solar system; a residence in Maine will generally require 10 kW.

This is because California gets more sunlight than Maine throughout the year. This means that California residents may only need about 28 solar panels for a typical house, while those in Maine will need around 40. The additional panels compensate for months with minimal sunlight so that the entire solar system can cover the energy needs of a household.

Keep in mind that an average American household uses 10,400 kWh annually with 250-watt panels. In this example, it will require 28 to 34 solar cells to supply the entire home for the rest of the year. However, your needs may be higher or lower than the average. Are you asking yourself, “How many solar panels do I need?” First, you should ask, “How many kWh will be enough for my home?”

Average kWh Production System Size Panels Needed
5000 4kW 13
6250 5kW 15
7500 6kW 18
9000 7kW 25
10000 8kW 30
12500 10kW 35
15000 12kW 40
21000 15kW 50
25000 20kW 60

How to Calculate Your Own Solar Panel Estimate

How does one calculate their own solar cell requirements? You can begin by determining your kWh consumption annually. Now, this is actually easier than you might expect as you just need to check out your electricity bill, and you can get a ballpark estimate of how much you are consuming year over year by multiplying the monthly number by 12.

Of course, you should recognize that your consumption may be higher in some months because of higher heating or air conditioning demands. So, take your latest bill and find that monthly consumption value. If you pay $120 on your monthly bill, then you may need a 10-kW system with 32 330-watt solar panels. If you are paying double that amount, then a 20-kW system may suit you better with double the panels.

The next thing you need to do is to calculate the amount of power that one solar panel can generate based on its efficiency. Normally, solar companies indicate whether their panels have 20% or 18% efficiency. Efficiency dictates the yield of your panels based on the amount of sunlight they absorb. For example, a 10-kW system with medium-efficiency panels needs to cover 508 square feet of panel spread. This requires approximately 40 250-watt average-sized panels.

Luckily, you will not need to make these calculations on your own. Solar panel system providers can give you a quote that will outline the expenses associated with going solar. Their expert installers and assessors can also answer you when you inquire, “How many solar panels do I need?” They will base their assessment on your historical consumption and on your household devices.

Factors that Will Impact the Number of Solar Panels You Need

One of the biggest decisions you will make when moving to a solar panel energy system is the number of panels necessary to enjoy the same energy consumption benefits of grid-based power. It is also one of the costliest considerations especially if you intend to fill your roof with as many as possible because of the number of residents in your household and the number of devices the solar system must sustain. What are the factors that actually impact this magic number?

There are four factors that may influence the quantity that your household requires. The previous sections have already touched on most of these factors. The first and primary contributor is your consumption.

Are you contemplating, “How many solar panels do I need for my house?” Then, you also have to determine how much electricity from the grid you currently pay for. To be more specific, you may want to go back 6 to 12 months when you make the assessment.

The next factor is your roof. Specifically, installers must look at the area of your roof that can be covered by the panels. They will examine your roof quality and roof shading and which portion of your roof would be suitable for the panels.

They will also assess the angle of your roof. The ideal roof for panel fixing will be at 30 degrees facing due south. Therefore, those with roofs not in this range may require more panels. 

The third factor is somewhat related to the second one. In order for your roof to get sufficient sunlight, it must be at a good angle towards the sun. Solar panel installers will normally have a device to measure this. If your roof has shading or is not at the ideal angle, then you could need more panels.

Finally, the quality of the panels that you select will contribute significantly to the quantity you need to purchase. If you buy new monocrystalline ones with high efficiency and high wattage, then you may not need a lot of panels.

Ideally, you should look for brands that promise at least 18% efficiency. Those with 20% or higher can really be beneficial in the long run. It may also be a good idea to look for ones with 20 to 25-year warranties because they likely have excellent quality and durability.


Indeed, going solar can be a complex and costly transition. It will also require you to make decision after decision, and it can cause frustration if you have so many things to think about.

However, knowing all the factors and all of your options will help you determine the best brands and methods for your needs. This will also save you a lot of money if you only buy exactly the quantity of solar panels that you need for the power that your home demands.

To make that decision easier, we have listed some considerations when making the decision, explained ways to calculate and arrive at a number of solar panels, and discussed the factors that may influence that number. The actual number of solar cells that you ought to have can be determined by checking your historical energy usage.

Then, you will have to get your roof inspected and measured for its sunlight absorption. You also must have your roof checked for the extent of available coverage.

Finally, you should consider the quality of panels and their actual wattage. With this, you can come up with the number of panels required to meet your kW requirement. If you are concerned about all these decisions, consult a solar panel provider. Some of them even offer free quotes.

With their help and your great decision-making skills, you can go solar in no time, enjoy practically free energy for the next 2 decades, and help the planet preserve its non-renewable energy for future generations to come.

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