How Much KWh Does a Solar Panel Produce?

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How much energy does a solar panel produce?

One of the best creations in the last few decades are solar panels 0 it’s undisputed! These nifty little devices help us to be able to keep our homes powered up for a cost efficient price, and in an eco-friendly way. They even help to keep a few extra dollars in our pockets in the long term. If you’re wondering how much power (kWh) solar panels produce and how many of them are needed by the average household, we’ve got some answers. Keep on reading this article to find out more about the amount of energy solar panels produce.

What are the main factors that affect how much electricity is produced by a solar panel?

There are a few different factors that affect how much electricity a solar panel will provide by each solar panel. Here are a few things to keep in mind. 


The very first thing that will influence how much electricity you will get from a solar panel is its size. Yes, this does sound obvious but it’s an undisputed fact. To put it into its simplest form, the bigger the solar panel is the more light it will absorb. In principle, should one solar panel be smaller and the other is larger, then theoretically the larger solar panel should absorb more sunlight and so it will produce double the amount of electricity that the smaller panel produces. If you need to be able to produce more energy, then we highly recommend getting larger solar panels. You will also need more of them for a particularly large household, which we will cover later in this article. If you’re only powering something like a tent or an RV, then the chances are you won’t need a solar panel that’s quite as large, you may even be able to get away with just using a portable solar generator, which you can easily store away in a closet when you’re not using it. 


This is the second factor that will influence how much sunlight your solar panels will absorb, and thus how much energy it will produce. Solar panels can be made with a variety of different materials, all varying in effectiveness. Let’s just give the two main types of solar panels for an example. One of the best options for materials for a solar panel is a monosilicon cell panel. These do have higher production costs but they are very efficient. You can also get polysilicon cell panels. These do cost a little less money but they also make a lot more waste and they simply don’t boast the same efficiency as a monosilicon panel. Newer creations and research does, however, mean that polysilicon panels are now almost as efficient as their monosilicon brothers. Because of that, it’s worth considering both and seeing what you would prefer. 

Amount of Sunlight

Considering solar panels are fuelled by light, sunlight will naturally affect how much power output you’ll get from your solar panels on a day to day basis. Solar panels use the sunlight and convert it into energy so this will directly affect how much power you get out of it. You should remember that solar panels don’t strictly need direct sunlight necessarily, as they can absorb light from a cover of clouds. Of course, being in direct sunlight will give you better results on that note. As you may imagine, things like the weather in your area will influence this, and you may get less sunshine in certain areas which can influence how effective your solar panels are. 

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How can you measure the efficiency of a solar panel? 

One thing you need to be mindful of is that your solar panel won’t always be 100% efficient. To put it simply, not all of the sunlight that it is capable of absorbing will be converted into usable energy for your business or home. Back when they were originally fashioned, solar panels would have about a 6% to 10% efficiency level but these days as technology has advanced they can be up to 30% efficient, perhaps more.

So how do you measure how efficient your solar panel is? Let’s find out! Consider that solar panel ratings aren’t always 100% correct, so there will be a little bit of room for error. When you’re calculating efficiency you should count with a deviance of ±2%.

1 - The very first thing to do is multiply the width and length of the solar panel so you can figure out how big the overall surface area of the panel is.

2 - try to work out what the power rating of the solar panel is (in watts). This element is the nameplate rating.

3 - Divide the number of watts that the panel is rated by the total surface area of the panel. For example, if your panel has a surface area of 1500 square meters, and then your panel’s rating is 250 watts, then you would divide 250 by 1500 and then you would multiply this by 100 to find the percentage. In this case, the solar panel would have an efficiency of 16.67% (250/1500) x (100) = 16.67%.

How is the solar panel power rating calculated?

By this point you’ll probably be wondering what the power rating of a solar panel is. The power rating of your solar panel is how much power every single solar panel is able to make for your home. You will have to know this as it will help you to be able to figure out how much of your electricity needs are able to be met by using the solar panels that you already have. 

There is a formula that exists purely to calculate the power rating of your solar panels. It’s a little bit complex so we’ll break it down for you.

The mathematical formula that you should use to determine the power rating is the following: E = A * r * H * PR. So, what do these things stand for? When you’re able to determine the value of every variable, just input the variables into the equation to give you the final power rating.

E = Total Amount of energy (kW)

A = Total surface area

R = efficiency rating

H = global radiation value

PR = Performance ratio

E (Total Amount of Energy in kW)

This variable stands for the total energy in kilowatts that your solar panel is able to make. Of course, this is the goal of the equation, as this is what you’re looking to find out.

A (Total Surface Area)

This variable signifies how big of a surface area there is on your solar panels. To work out how much of a surface area you have, you just need to multiply the width and the length of the solar panel by each other.

R (efficiency rating)

This will give you the efficiency level of your solar panel. We covered calculating this in the above section. Again, if your panel has 250 Wp and measures 1.6 meters squared in surface area. Your efficiency here will be equal to 15.6%.

H (Global Radiation Value)

As the name suggests, this element signifies the global radiation value. This is also known as the average amount of sunlight based radiation that your area in the world gets. Norway would get an average of 200 kWh/m2 per year for example, meanwhile Saudi Arabia gets 2,600 kWh/m2.y. In order to get this variable, check the solar radiation data for the area you live in.

PR (Performance Ratio)

This signifies the performance ratio of your solar panel. When solar panels absorb light there are a number of power losses that can occur. This is light energy that isn’t converted into power that you can use as a result of a few processes and bits of equipment. 

Up to 10% in power losses can be caused by inverter losses, while temperature can account for around 20%. DC and AC cables make up 6%, and then there are a number of different other variables that contribute to power losses.You need to figure out what your panel’s performance ratio is first before you can figure out the power rating.

How much energy will my solar panel produce per square foot?

This largely depends on the panel you choose, as you may have guessed from the information we covered above. It’s important to determine how much energy each square foot of solar panelling produces when it comes down to determining how big you need your solar panel to be for the roof of your house. To put it simply, when you’re aware of how much power the panels give out then all you need to do is divide it by the square feet of the panel. For example, if your panel gives out 265 watts and measures 65.4 by 39 inches, then the energy that the panel produces per square foot is roughly 15 watts. This may not sound like an awful lot, but they really do add up quite fast. 

How much energy can my solar panel produce per month and per day?

Now you know how much energy one lone solar panel can produce. From here, you’re able to work out how much power it is capable of producing on a daily and monthly basis. As a quick example, if you possess a 250 watt panel, all you need to do is multiply the amount of watts by the amount of usable sunlight that your roof is likely to get in a day. If you’re in the US, your average amount of full usable sunlight in a day is roughly 4 hours.

In order to work out how much power your panel can produce on a daily basis, all you need to do is multiply the amount of watts by 4 hours, so in this case 250 watts by 4 hours. This correlates to 1000 watts a day. In order to work out how much energy the panel produces on a monthly basis, multiply the 1000 watts by 30 or 31 days depending on the month (this will obviously be different for February!). As an average, you may expect a given solar panel to be able to generate around roughly 30000 watts on a monthly basis. 

How much power will I need for my electrical appliances?

This is not a specific question, and is a little difficult to answer as all appliances are different. Some will be very energy efficient, while others may not be. This is vital when you’re on the hunt for a portable solar panel system to use with your RV. For example, most fridges on average will use roughly 1 and 2 kWh, and older models usually use more than this. Things like water heaters can use up to 4,500 watts depending on the size of the family using them. Other things that use lots of energy are heaters, washers, dishwashers, dryers and others. If you have a large family, then you’ll probably not be able to power the entire home purely using solar panels. If you do have a sudden power outage that you’re not expecting then having a portable solar generator in the house can still be quite helpful.

How many solar panels do I need for my household?

This is also a somewhat tricky question to answer as it can largely depend on a number of variables, such as how large your space is, or how many people live in the home, and how many appliances are in use at that time. The average household will use roughly 37 kWH per day. If your solar panels are able to create 2 kWh of power a day, then in order to fully power your home you will need 37 solar panels in order to completely power your home. With that being said, you should keep in mind that there are a number of variables to consider here, so this is nothing more than a rough estimate. 


If you’ve read this far, you’ll know that there is an awful lot of maths and science involved in calculating how many kWh a solar panel is able to produce on a day to day basis. It may sound a little like a high school physics lesson! There are so many different variables that go into calculating how many kWh a solar panel is capable of producing on a daily basis, and how much the final power output they produce will be. You should make sure that you do any necessary research before you put up any of your own solar panels to ensure that you have exactly what you need.

If you want to find out more, then you should read a buyers guide of DIY Solar Panel Kits so that you’ll know the exact things that you need in order to be able to install solar panel systems at home.

And that’s everything! Hopefully this guide has helped you to be able to understand how much kWh a solar panel needs to generate enough electricity to power your home. Hopefully your head isn’t completely spinning and it made sense. 

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