How Many Solar Panels Are Needed to Run a House?

Updated on November 7, 2022
How Many Solar Panels Are Needed to Run a House?

A home’s power needs, solar panel watts and location irradiance are needed to calculate solar power system size

A typical house in the U.S. would need 20 to 25 solar panels to run it, which will have an average cost of $20,000 and covers 100% electricity usage for the home. The exact number of panels needed to run a house will depend on where you live, how much power the panels can generate, and how much power you need.

Using solar energy is one of the best ways to reduce our carbon footprint and reverse the effect of global warming. If you want to install solar panels, you will need to know how many solar panels would be enough to power your home.

How do I calculate how many solar panels I need to run a house?

Electricity usage vary from house to house depending on number of appliances used and how much electricity needed. In this article, we will consider average energy consumption in homes and either assume average peak-sun hours, or for some locations, we will use actual irradiance.

The number of solar panels you would require for your home will determine how much you will have to spend for the total installation.

The more the energy required, the more panels to be installed. A single panel will not be able to generate the financial benefits of using solar energy; you need to power your home sufficiently.

The geographic location and individual panel qualities are some of the key factors that determine the number of solar panels required. For instance, in Massachusetts, you will need more panels to produce output similar to what you will get in California.

Video – How many Solar Panels do I need to power my house?

How many solar panels are needed to run a typical house?

Here is how you calculate the number of solar panels your home would need.

i) How many kwh does a house use per year?

This is the amount of energy you use in a year in your home depending on the electric appliances you use, amount of energy they require, and how often they are used.

The appliances may include television set, refrigerator, lights, air conditioning unit, microwave and kitchen appliances, chargers and other equipment that require electricity to run.

The US Energy Information Administration (EIA) reported that an average American home consumes 10,715 kWh of power yearly.

Rooftop solar system can supply this electricity and offset all usage and electricity bills to know your exact needs, you should check your previous year’s utility bills to know what you used.

ii) Solar panel wattage – How many watts is the average solar panel?

The wattage of a panel is its power rating; the amount of power a panel generates under perfect conditions. Most solar panels have a power rating of 250W to 400W and for our calculations, we’ll take 340W.

iii) Solar PV system production ratio

This is the ratio of the estimated power output over time (kWh) to actual system size (W). It is hard to achieve a 1:1 ratio as the system largely depends on the amount of sunlight it receives which is a variant.

A 10kW system, for instance, can produce 14kWh power per year and its production ratio is calculated as 14:10, which is 1.4. Most solar panel system in the US have a production ratio ranging from 1.3 to 1.6.

These three factors are essential in calculating the number of panels you would need for your home. i.e.,

Number of panels = system size / production ratio / panel wattage

Taking the figures above, we get 10,715/1.3 or 1.6/340 which will give us 20-24 panels depending on the ratio used.

How many solar panels to power a house in UK?

How many solar panels to power a house in UK?

Not known for it’s sunny days, UK does get 4 peak sun hours per day on average

The number of peak-sun-hours in your region also counts significantly in determining the number of solar panels you would install. Different regions have varying sun hours depending on the seasons. Your roof size is also crucial to know how many panels can fit on it.

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You can calculate how many solar panels you can buy for your system in the UK by taking into account energy usage of the house, energy produced by the system, your roof size, and the sun hours in your region.

Due to some unavoidable circumstances such as inadequate roof size, the solar energy produced can be supported by the grid. In this way, you would not be getting all your electricity needs from the solar system.

In the UK, averagely, most homes use 3 to 6kWh electricity in a day with some people using solar energy to power a fraction of what they need. This is to reduce the number of panels to be installed.

The UK is a place not known for its sunniness. During winter and a part of autumn, the place can covered with snow almost the entire day. However, you should not be worried as there is an average of 4 peak sun hours daily throughout the year which means that a solar system could be of benefit.

Different regions in the UK have varying average sun hours:

  • Northern Ireland has 3.2
  • Wales 3.3
  • Scotland 3.7
  • England has 4.1.

Before kicking off your installation project, it is crucial to consult with your local installer.

How many solar panels do I need to run a family home?

The energy usage in a home could depend on the number of family members living there. Where there are more than five people, a 6kW solar panel system is ideal whereas where there are four people 5kW system is enough.

Most families, however, have three or less people and in these types of homes, a 4kW system is the most common.

The energy required and size of the panels will determine how many panels you will require. For instance, a 6kW system of 250W panels will need 24 panels whereas a 3kW system will take 12 panels.

In solar panels system installation, to know how many panels you would need, you should know how much energy a single panel produces. A panel’s wattage size is the watts per sun hour the panel could produce.

A 300W panel can produce up to 300 watts in a sun hour whereas a 350W panel can go up to 350 watts in a sun hour. It is, therefore, crucial to know how much energy your home uses before installing a solar system.

For a daily 4kWh energy consumption, 16 solar panels of 250W each would be needed for 100% electricity supply.

4000 Wh / 250 W= 16 solar panels.

You can do the calculation varying on the capacity of your panels and energy requirements.

Solar panel producing companies have their products in different dimensions. Thus, the spaces they occupy varies. As the roof capacity is limited, there is a maximum number of solar panels your roof can hold. Panels of different wattages also have different dimensions.

For example, 16 panels of 250W will require a roof of 25.6m2 surface area whereas 12 panels of 350W require 22.8m2.

How many solar panels do I need to power a refrigerator?

How many solar panels do I need to power a refrigerator?

How much solar would it take to run a fridge?

Solar panels come in different capacities, from 50W portable panels for charging devices to powerful 300W rooftop panels. There is a panel size for every need, and for large scale energy production, you can use a combination of several panels.

An average refrigerator in the US uses about 57kWh of energy monthly whereas a freezer uses approximately 58kWh and together use 115kWh. This would require 3 or 4 average solar panels with ratings of 100W.

A panel in the sun for at least 8 hours will generate about 1kWh daily, equal to 30kWh monthly. To achieve the required energy of 115kWh, you would need to install four such panels,


However, if you are using a stronger panel, for instance 300W, in the same sunlight, it would produce 2.5kWh daily. This would translate to a monthly energy production of 75kWh.

To power the same refrigerator system, two panels would produce 150kWh per month, which means there would be surplus in energy which you can use elsewhere. A 500W solar panel on the other hand, given the same conditions, would produce an estimate of 4kWh daily.

In a month, a single panel would be enough to power the same refrigerator setup producing 120kWh electricity per month.

Depending on where you are, and the sun hours your solar panels would be receiving daily, you can calculate how many solar panels would be enough to power a refrigerator. The energy production of each solar panel will also determine the number of panels you would need.

How much solar to run a refrigerator calculator

How many solar panels do I need for a four-bedroom house in USA?

A 4-bedroom house is relatively big and means that there are many occupants in it. This means that the energy consumption would be high and would require more solar panels.

If for instance, each room has a television set, bathroom, and other electric appliances, the house might require up to 25 panels of 300W each.

On average, a 4-bedroom house in the USA requires 7.75kW solar panel system. When using 375W panels, you will need to install 21 panels.

With a 500W solar panel, you would require about half the number of panels compared to the previous. With a higher wattage, it means that there is more space saved on the roof.

Two combined 250W panels take up more space compared to a single 500W despite the fact that they would be supplying the same amount of electricity.

How many solar panels do I need for a 1,000 square feet home?

A 1,000 sq feet home would require a solar panel system of 2.66kW. To produce this electricity with panels of rating 375W, you will have to install eight panels. Nine panels of 315W each would also be able to power the same home.

To arrive at these figures, we have used the average household square footage against their average monthly consumption. However, depending on your annual power usage, you might need a bigger or smaller system.

How many solar panels to run a 2,000 square feet house?

A 2,000 square feet home will be well powered by a 5.32 kW system. To get such a power output, you should install 15 panels rated 375W or 17 panels rated 315W. This system is sufficient to serve an average American home of 2,000 feet.

Keep in mind that it still comes down to specifics to get an exact number of panels or system size depending on your region, power usage, and budget.

How many solar panels to power an average house? (calculator)

How many solar panels to power a house off-grid?

If you are looking to fully power your house off-grid, it means that you are going to be independent of the electric grid. Also called a stand-alone power system, you would be 100% powering your house using solar panels.

Your house is connected to the grid but you will not be using any electricity from the grid. For a long time, going off-grid have been for a few who can afford expensive inverters and batteries comfortably.

However, prices have been dropping and many can now afford and many more will be affording it with time.

To go off-grid, it means that your system will be able to produce the same energy you have been using. For the perfect off grid solar system, check your annual usage from electricity bills. Let us take for instance you have 300W panels and would have average of 8 sun hours daily.

Annually, each panel will generate about 900kWh per year. On average, a home uses 11,000kWh power annually which means that you will need about 13 panels to 100% solar-power your home off grid.

To go off-grid, you will have to part with about $25,000 to $45,000 in installation costs.

How many solar panels to power a house on-grid?

On-grid system means that you will be powering your home partially with grid electricity and solar power. Most people using this system will use solar power during the day when there is the sun and at night use grid electricity.

An on-grid system is affected by blackouts as power might flow into the lines while repairs are ongoing.
An on-grid system does not require as many panels as off-grid – whenever the solar power falls, grid electricity comes in to power the system.

Five 300W solar panels are enough to power your home on-grid although it might vary depending on energy requirements

How many solar panels do I need for 3,000kWh per month?

An average American home uses 900kWh power per month which is supplied by 20 to 25 solar panels rated 300W. If you need to produce 3,000kWh per month, it means that you are operating a farm or company.

Using 315W panels, you will need to install 64 to 69 panels to achieve 3,000 kWh power output. With 375W panels, you will need 58 to 60 panels.


Can solar power run a whole house?

Solar power can power a whole house 100% and at the same time can be inadequate. The number of panels installed, output of each and the energy usage come into play.

The combined output from the entire system should match what the household requires to ensure that there is no straining. If a low energy system is installed in a household with a relatively larger energy requirement, the system will not be able to run the house.

In such a case grid electricity is used to fulfill the home’s energy requirements. Before installing a system, if you need it to power 100% of your house’s electricity, you should check your energy usage from previous electricity bills.

You should then calculate how much each panel will be producing at average conditions depending on your area and install number of panels that would be able to produce your required electricity.

Is 5kW enough to run a house?

A 5kW solar system can power 100% of a house usage. As discussed, there are several other factors that come in play such as the energy consumption in the house. On average, a 5kW system is a good fit for a house with four people.

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Resources relating to solar power for the typical house

Solved! Here’s How Many Solar Panels to Buy to Power a House

How Many Solar Panels Does It Take to Run a House?

How Many Solar Panels Are Needed To Power A House?

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