How Much Electricity Does a Solar Panel Produce?

Are you trying to work out an answer to the question “How much electricity does a solar panel produce”? Join us as we dive into everything you need to know about solar panel efficiency.

If you’re interested in installing a solar project on your land, you’ll want it to be as efficient as possible. After all, higher efficiency will lead to greater profits.

In this comprehensive guide on solar panel efficiency, I’ll be covering the average electricity a solar panel can produce. But I’ll also look at the key factors that influence how much electricity a panel produces over time.

I’ll cover everything from weather conditions and sunlight hours to UV degradation. My aim is to help you understand all the variables that can affect how much energy your solar panels generate.

Now let’s get started.

How Much Electricity Does a Solar Panel Produce?

If you’re wondering, “How much electricity does a solar panel produce?”, you’ll need to look at watts and kilowatt-hours (kWh).

The average solar panel has a power output rating between 250 and 400 watts (for domestic-style panels). As a rule, a panel of this wattage should generate around 1.5 kilowatt-hours of energy daily.

This generally applies to homes that receive at least six hours of sunlight daily. If you have excellent conditions near you, your panels might produce more.

Regarding the energy that can be produced by a super large-scale solar farm, you can expect between one and five gigawatts of electricity annually. The largest solar farms produce mind-boggling levels of electricity, with the biggest (Golmud Solar Park in China) spanning 640 acres and boasting a 2.8 GW capacity.

Smaller solar farms with one-megawatt capacity will produce around 2,146 megawatt-hours of energy per year. This is enough to power over 725,000 homes. These figures will vary based on weather conditions and inverter efficiency, but it’s a decent ballpark.

However, not every solar panel is made equal. Some are more efficient than others (and this is largely down to their materials and external conditions). Solar panel costs can also differ across types and suppliers, which is something to consider before diving in.

But don’t worry, I’ll get to that.

How Efficient Are Solar Panels?

Solar panel output and efficiency depends on a few factors, with the most significant variations coming from the materials used.

There are several different types of solar panels, each with its own level of efficiency.

Let’s quickly run through them (for a more detailed rundown, feel free to check out my blog on types of solar panels.

Monocrystalline

• Monocrystalline panels are the most efficient solar panel types as they use high-quality, single-crystal silicon. So, they’re far better at turning solar energy into electricity.

•  They tend to have a higher potential output per panel, meaning you’ll need fewer panels to run your home or project.

• On average, they have efficiency ratings between 15 and 24 per cent, but it tends to sit around the 20 per cent mark.

•  They can last 30 to 40 years if properly taken care of.

•  Their only downside is that they’re far more expensive than alternative panels.

Polycrystalline

• Polycrystalline panels have an average efficiency of around 13 to 16 per cent.

• These panels are formed into a cube and cut into thin, wafer-like shapes.

• There’s usually less waste in producing these solar panels as they aren’t pure silicon. However, they will have imperfections on their surface, making them less efficient overall.

• They last less time than monocrystalline panels and tend to perform optimally for 25 to 35 years if they’re well-maintained.

Thin Film

• Thin Film panels are thin, flexible in profile and made from semiconducting materials like silicon, cadmium telluride and copper indium gallium selenide.

• They tend to have lower efficiencies than the other panels I’ve mentioned, with efficiency ratings reaching 11 per cent.

• They degrade more quickly, making them largely unsuitable for large-scale solar projects.

It’s worth mentioning that larger systems will naturally generate more electricity, but choosing more efficient panels can seriously improve overall output.

Additionally, solar panels are only getting more efficient over time. Believe it or not, there are solar panels in development that have reached 42 per cent efficiency under lab conditions. If these panels can be deployed in residential and large-scale projects, we’re far more likely to meet net-zero limits by 2050.

And if that wasn’t enough, a more efficient panel system will likely boost the potential income from large-scale solar projects. The more efficient the panels, the more energy can be sold to the Grid.

Now, that’s food for thought.

What Can Affect How Much Electricity a Solar Panel Produces?

We’ve started answering the question, “How much electricity does a solar panel produce?”, but there are still a few things to consider.

The amount of electricity solar panels produce can be influenced by various external factors.

Let’s take a closer look at the key factors that can impact the overall efficiency of your solar panels.

Panel angles

For a start, you’ll need to ensure your solar panels are at a practical angle to capture as much irradiance as possible. This is usually between 30 and 45 degrees (called the azimuth angle).

The panels will be most efficient when the sun’s rays are perpendicular to the panels’ surface – usually during the brightest daylight hours.

However, it’s worth noting that the panels won’t always be in the ideal position as the sun moves throughout the day. Still, aiming for this alignment gives the best chance of maximising energy production (especially when there’s naturally less sunlight).

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Weather factors

Weather is probably the most significant factor that can affect what solar panels produce. Once your panels are in the correct position, you’re essentially at the mercy of nature.

Hail can cause around 0.1 per cent of solar systems to underperform, while snow can cover panels and ice can build up on the surface of the cells.

Ice buildup is particularly concerning, as it can potentially decrease solar panel efficiency by 25 to 100 per cent, making it a major efficiency consideration during the winter months.

Snow is also quite problematic if it becomes thicker than 5 cm. In such cases, you’ll need to manually remove the snow to ensure your panels continue capturing energy. While the tilt of your panels should do this automatically, it’s something to consider if there’s particularly adverse weather around.

Interestingly, some weather elements can actually help improve a panel’s performance. For example, wind cooling can marginally increase efficiency by around 0.05 per cent by preventing overheating. It’s not much, but every little helps.

UV Degradation over time

Nothing lasts forever, and solar panels are bound to degrade gradually over time. As a result, the amount of energy they produce will decrease over time.

Most manufacturers guarantee upwards of 90 per cent performance for the first 10 years. However, your panels will naturally degrade by around 15 per cent during their lifetime.

If you’re wondering why this happens, it’s because the solar cell structure delaminates under UV rays.

This heavy radiation also causes the discolouration of solar cells, forming a layer of boron oxide that causes an efficiency dip of 1 to 3 per cent in the first 1,000 hours.

While this degradation might be disappointing, you can reduce the impact by:

• Choosing high-quality panels
• Installing your panels correctly
• Maximising the angle of your panels
• Keeping up with maintenance and clearing any debris and dirt from the panels
• Reducing scratches

Inverter or battery efficiency

Another thing that can affect the efficiency of solar panels is the inverters and batteries you choose to use.

The inverter is crucial to any solar system as it converts DC power (direct current) to AC power (alternating current). Once the current changes to AC, it can be safely used for homes, businesses, and everything in between.

However, as these systems are never going to be 100 per cent efficient, they often affect the overall output of a solar system.

A small amount of energy will always be lost in the conversion process, but the best inverters will be around 93 to 96 per cent efficient. If you find that the converters you have chosen are significantly less efficient, switching to micro-inverters might be worth it.

You’ll also want to keep your inverters well-serviced and monitored to avoid any unexpected breakdowns. This way, you’ll immediately know if something is affecting the output of your system.

The daylight hours

Reduced daylight hours will dampen energy production from any solar panel.

In the UK, we get an average of four hours of sunlight daily. This increased slightly in 2022 to 4.9 hours, but we don’t generally get much.

On the other hand, China gets an average of five hours and seven minutes of sunlight every day. This alone explains why the country is home to one of the largest solar farms in the world.

These figures represent an average day, but it is worth noting that any country might get more sunlight hours than the average during the summertime. Equally, there may be overcast days where irradiance is lower, leading to lower solar panel efficiency.

This fluctuation in sunlight means it can be difficult to fully measure the efficiency of a panel, as sunlight levels vary on a daily basis.

Temperature

During the summer months, the UK can get hot. However, it’s important to note that higher temperatures can actually decrease a solar panel’s output.

Although this might be surprising as panels rely on sunlight, higher operating temperatures can cause severe power dips.

A 2011 study on the Effect of Temperature of Photovoltaic Cell Efficiency found that at 25 degrees Celsius, wattage stood at around 50.2 Watts. At 70 degrees Celsius, this dipped significantly to 39.3 Watts.

So, when planning a domestic or commercial solar installation, it’s worth considering ways to keep your panels cool. This way, you’ll lose as little output as possible (and increase the income from your project).

Final Thoughts

It’s tough to provide an exact answer to the question, “How much electricity does a solar panel produce?”. And that’s because it varies considerably based on the type of panel, the weather conditions and UV degradation over time.

But generally, monocrystalline panels are the most efficient option (which is why they’re the top choice for solar farms). Plus, with proper maintenance and keeping them free of debris, you can ensure they operate at their best.

If you’re considering  installing solar panels on your land and need a helping hand, get in touch. While we don’t handle installations, we can certainly help landowners figure out the financial potential of a large or small-scale solar project. You’ll definitely want to know the numbers.

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