Solar Panel Output: How Much Electricity Do They Produce?

✔ A solar panel's power output is measured in kilowatts (kW)

✔ A three-bedroom house will typically need a 3.5 kilowatts peak (kWp) system

✔ Solar panels cover roughly 50% of household electricity needs

Investing in solar panels costs a pretty penny, so it can be daunting if you’re not familiar with the lingo – and ‘solar panel output’ is a daunting level of jargon. But we’re here to make it easier for you.

We’ve compiled all the need-to-know things when it comes to making sure you have the right amount of power flowing out of your panels.

Already familiar with all things solar? Dive in and get yourself a quote for a new solar panel system with our simple comparison tool.

Once you’ve filled in a few details, our suppliers will be in touch with quotes for you to compare. You’ll find the right deal in no time, allowing you to make vital savings during this cost of living crisis.

What is a solar panel’s typical power output?

Let’s start off with the basics – a solar panel's output is expressed in watts (W).

The higher the wattage of a solar panel, the more electricity it can produce under the same conditions. These conditions will depend on where you live, the angle of the roof, and the direction your home faces.

A typical solar panel is rated 350 W, which is a measurement of power. A solar panel with this level of power will produce an average of 265 kilowatt hours (kWh) of electricity per year in the UK. For context, a kilowatt hour is used to measure the amount of energy someone is using; you’ll often find it on your energy bills.

If a homeowner’s solar panel system included 12 of these panels, it would produce an average of 3,180 kWh of electricity per year.

Average solar panel output per day

The average 350 W solar panel will generate about 0.72 kWh of electricity per day. But this is only one panel. The average three-bedroom property needs a system with at least 10 panels to cover its electricity needs (although half of this electricity won’t actually get used – but more on that later), meaning the whole solar panel system would produce 7.2 kWh of electricity per day.

Solar panel output per m²

The output per m² of an average 350 W solar panel in the UK is 132.5 kWh.

How much power can a solar panel system generate for your property?

If you get a decent installer who can accurately assess how much electricity your solar panel system will need to produce, it should generate roughly as much electricity as your property uses.

However, you’ll only actually end up using about 50% of this electricity, unless you have a battery to store electricity during the evenings and times when you’re out of the house – in this case, you’ll end up using about 80% of the electricity.

Check out the table below to see how much electricity different sized solar panel systems can produce for various properties. Or, you can read about 5 kW solar panel systems specifically and find out if this size system is right for your property.

Use our solar panel output calculator to work out what number and peak power output of panels you need.

Why do solar panels only cover 50% of your electricity needs?

One of the main drawbacks of solar panels is that you can only consume the electricity they produce in real time – whilst you’re in the house, during the daytime.

Solar panels won’t produce any electricity during the evenings, because there’s no sunlight for them to absorb. On top of this, people aren't typically at home all day to use the electricity generated by solar panels. These are two key reasons why solar panels can only really cover 50% of homeowners’ electricity needs.

There is always the option to pair a solar panel system with a storage battery, which allows homeowners to store any surplus energy their panels produce.

But even then, the homeowner will only be able to use up to 80% of their solar-generated electricity, as battery technology still has limited capacity levels. The remaining 20% ends up going back to the grid.

Solar panel output: winter vs summer in the UK

Although solar panels work all year round, their output levels fluctuate throughout the seasons. This boils down to the changes in the amount of sunlight exposure the panels get each month.

As you might have guessed, solar panel output reduces during the winter in the UK – by 83%, on average.

This is because the days are shorter in the winter months, meaning panels aren’t exposed to as much sunlight as they are in the summer. The sun is also lower in the sky during the winter, which can impact sunlight exposure, and it's usually cloudier.

High output solar panels

If you really want to get the most out of your solar panels, you might want to look into products with a high output rating.

To help you get a headstart, we’ve listed the most powerful panels on the market in the table below.

These figures were sourced from our research of the best solar panels on the market. Want to take a look at the findings? Head to our Guide to the Best Solar Panels in the UK.

How to monitor solar panel output

It’s important to monitor how your solar panels are performing on a regular basis, to make sure they're generating the expected amount of power. If your solar panels' power output is particularly low, it could be a sign of a problem.

One way you can do this is by checking the solar panel meter that will be placed in an accessible location within your home. This meter will record the amount of electricity being produced by your solar panels.

But to make things even easier, some solar brands have rolled out online monitoring tools, which means you’ll be able to see how much power your solar panels are generating with the click of a button on your computer or phone.

There are also a number of apps that solar panel owners can download that can give you an insight into how your system is running. Some of the most popular apps include:

• SolarEdge Monitoring
• Energy Monitoring & Analysis App (EMA)
• Enphase Enlighten App
• SMA Sunny Portal App

What affects how much electricity a solar panel can generate?

If conditions aren’t ideal, your solar panels’ efficiency will take a hit, meaning they won’t be able to work at their maximum power output.

There are several factors that can impact how much electricity a solar panel is able to generate. These include:

Direction and angle of your roof

A solar panel works at its best when installed on a south-facing roof at a 35-degree angle. However, solar panels can still produce a decent amount of power on an east-facing or west-facing roof, and at an angle anywhere between 10 and 60 degrees.

Most houses will fit this description – which is fortunate, since you can't change the angle of your roof without a lengthy, difficult process that involves a complicated frame system and new planning permission.

You can learn more on our page: What’s The Best Angle and Direction for Solar Panels?

Shade

Make sure your solar panels are installed out of the shade, in direct sunlight. If just a small amount of shade covers a solar panel, it can significantly reduce how much electricity it’s able to generate.

Time of the year

A solar panel will produce more power in the summer months when the days are longer and there are more sunshine hours.

If it gets too hot, however, solar panels can overheat; if their temperature goes over 25°C, they'll generate slightly less power.

Dirt

If a solar panel is covered in debris, its power output will fall because sunlight will be stopped from hitting the panel. Thankfully, there are a few ways you can protect your solar panels from this.

Make sure you regularly clean your solar panels in the evening with a hosepipe, as long as the jet of water can reach them.

If your panels are seriously soiled, a professional clean may be worthwhile – and remember: although it rains a lot here in the UK, don’t rely on downpours to wash away the dirt.

You can find out more on our helpful guide Reasons Solar Panels Lose Efficiency Over Time (And How to Slow It Down).

How will you know how much electricity your solar panels generate?

Your solar panels will come with a meter that will be placed in an accessible location within your home. This meter will record the amount of electricity being produced by your solar panels.

Some solar brands are also rolling out online monitoring tools, which means you’ll be able to see how much power your solar panels are generating with the click of a button on your computer or phone.

As solar panels require virtually no maintenance, it can be easy to forget about them once they're installed on your roof. We'd recommend checking them regularly, however, to ensure they're clean and in good condition.

It's worth monitoring your meter frequently too, to make sure they're generating the expected amount of power. If your solar panels' power output is particularly low, it could be a sign of a problem.

Finding an installer

Feeling more clued up on solar panel output? Well then, perhaps now’s the time to make the switch to solar.

After all, a majority of people want to go solar, according to our National Home Energy Survey.

Plus, just like we’ve simplified solar in this article, we can make the comparison stage easier for you too!

The only thing you need to do is put a few details in our easy-to-use comparison tool – then put your feet up and let us do the hard work. We’ll pass on your information to our suppliers, who’ll then be in touch shortly with free quotes for you to compare. You’ll be reaping the solar-powered rewards in no time!

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