How Much Electricity Does a Solar Panel Produce?

Topic: new solar projects Read Time: 8 mins
Landowner type:
Independent landowners | Institutional landowners | Professional advisers | Site Operator
Energy: Solar
Back to Blog

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 getting 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 go-to guide on solar panel efficiency, we’ll cover the average electricity a solar panel produces. But we’ll also be looking at the main factors that can affect how much electricity a panel produces over time. From weather issues to sunlight hours and UV degradation, we’ve got everything you need to consider.

Now, let’s get started.

If you’re asking yourself, “How much electricity does a solar panel produce?” then you’ll need to look at watts and kilowatt-hours. The average 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 (kWh) 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 energy produced by a super large-scale solar farm, you can expect between 1 gigawatt and 5 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.

If we look at smaller solar farms with 1 megawatt capacity, they’ll produce around 2146 megawatt-hours of energy per year. This is enough to power over 725,000 homes every year. These figures will vary based on weather conditions and inverter efficiency, but it’s a decent ballpark.

However, we decided to add a slight addendum to this by saying that not every solar panel is made equal. Some are more efficient than others (and this is largely down to their materials and external conditions). But don’t worry, we’ll get to that.

The efficiency of solar panels depends on a few factors, but the most considerable variations are down to materials. There are a few different types of solar panels that vary in efficiency. Let’s quickly run through them right here (for a more detailed rundown, feel free to check out our blog on types of solar panels.

Close-up photo of a monoycrystalline solar panels
  • 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%, but it tends to sit around the 20% mark.
  • They can last 30-40 years if properly taken care of.
  • Their only downside is that they’re far more expensive than alternative panels.
Close-up photo of a polycrystalline solar panels
  • Polycrystalline panels have an average efficiency of around 13% to 16%.
  • 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, this means that they have imperfections on their surfaces, making them less efficient overall.
  • They last less time than monocrystalline panels and tend to perform optimally for 25-35 years if they’re well-maintained.
  • The last type of solar panel that you might see is thin film.
  • They’re 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 we’ve discussed, with efficiency ratings reaching 11%.
  • These panels also 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. Plus, it’s worth stating that solar panels are only getting more efficient as time passes. Believe it or not, there are solar panels in development that are reaching 42% under lab conditions. If we can get these panels working on homes and large-scale projects, we’re far more likely to meet net-zero limits by 2050.

If that wasn’t enough, more efficient panels will likely boost the potential income from large-scale solar projects. The more efficient the panels are, the more energy can be sold to the grid. Now, that’s food for thought.

While we’ve started answering the question, “How much electricity does a solar panel produce?” we’re not quite finished. And that’s because the amount of electricity a panel produces can be affected by external factors. Let’s take a closer look at the things that might affect the overall efficiency of your solar panels.

Rows of solar panel set at an angle

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 rays are perpendicular to the panels’ surface – just for reference; this is usually during the brightest daylight hours.

It’s worth noting that the panels won’t always be in the best position as the sun moves throughout the day. But this gives you the best chance of battling nasty weather (when there’s naturally less sunlight).

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

Hail can cause around 0.1% of solar systems to underperform, and snow can cover panels. Ice can build up on the surface of cells, potentially decreasing solar panel efficiency by 25 to 100%, so it’s a major efficiency consideration during the wintertime. Snow is also quite problematic if it becomes thicker than 5cm. And that’s because you’ll need to remove the buildup for your panels to capture energy manually. The tilt of your panels should do this automatically. But it’s certainly something to consider if there’s particularly adverse weather around.

Some elements of weather can actually help a panel. For example, wind cooling can marginally increase efficiency by around 0.05% by preventing overheating. It’s not much, but every little helps.

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% performance for the first ten years. However, your panels will naturally degrade by around 15% 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 discoloration of solar cells, forming a layer of boron oxide that causes an efficiency dip of 1-3% in the first 1000 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
Sun's rays reflecting on solar panel's surface

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% 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 93-96% efficient. If the converters you choose 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 (and in good time, too).

Reduced daylight hours will damper energy production from any solar panel. In the UK, we get an average of four hours of sun daily. The figures boosted slightly in 2022 to reach 4.9 hours, but we don’t generally get much.  On the other hand, China gets an average of 5 hours and 7 minutes of sunlight a day. This alone explains why the country is home to one of the largest solar farms in the world.

Although this accounts for an “average” day, a country might get more sunlight hours during the summertime. Equally, there may be overcast days where irradiance is lower. So, it’s tricky to thoroughly measure the efficiency of a panel as sunlight levels are constantly changing day to day.

During the summer months, the UK can get HOT. And if the temperature increases significantly, the output from a solar panel decreases. Although this might be surprising as panels rely on sunlight, higher operating temperatures can cause severe power dips.

A study on the Effect of Temperature of Photovoltaic Cell Efficiency from 2011 shows how operating cell temperature affects output. At 25 degrees Celsius, wattage stood at around 50.2W. At 70 degrees Celsius, this dipped significantly to 39.3W. So, it’s worth trying to keep your panels cool when mapping out a domestic or commercial-scale project. This way, you’ll lose as little output as possible (and increase the income from your project).

An infographic showing the effect of temperature on solar panels

It’s tough to provide an exact answer to the question, “How much electricity does a solar panel produce?” 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 panels that you can choose (which is why they’re the top choice for solar farms). Plus, you can always take steps to maintain your panels and keep them free of debris.

If you’re considering putting solar panels on your land and need a helping hand, get in touch. While we won’t install them, we can help landowners figure out how much they can make from a large-scale solar project. And trust us, you’ll want to know.

Discover the Solar Potential of Your Land

Contact Us to Assess Your Property’s Suitability for a Solar Project.