Understanding solar panel output is crucial if you’re considering investing in solar panels. Knowing how much electricity your panels can generate is key to determining both the environmental and financial benefits of your investment.

Switching to solar is not only an excellent green choice, helping to reduce your carbon footprint by about one tonne per year, but it’s also a smart financial decision, potentially saving you up to £600 annually on energy bills. However, the actual savings and return on investment are directly tied to your solar panel’s output.

The amount of electricity your solar panels produce depends on various factors, including location, weather conditions, and panel efficiency.

By understanding these factors and how they impact output, you can better estimate your potential savings and make an informed decision about your investment in solar energy.

This guide covers everything you need to know about solar panel output, from the basics of how it’s measured to the variables that can influence it, helping you maximise your benefits from going solar.

Pro tip: Avoid upsells and confusing packages—choose a provider with a clear, fixed-price quote that won’t change. Heatable, a Which?-approved solar installer, offers transparent pricing with no surprises.

Quick Takeaways:

• The actual output of your solar panels will vary depending on the type of panel, orientation, location, temperature, shading, and installation.
• You can improve solar panel output by getting high-quality products, monitoring their performance, and hiring an MCS-certified installer.

What Is Solar Panel Output?

Solar panel output is the amount of electrical power a solar panel can produce when exposed to sunlight and is typically measured in watts (W) or kilowatt hours (kWh).

A solar panel’s wattage measures how much energy it can produce under standard testing conditions.

Manufacturers use Standard Test Conditions (STC) to rate solar panel output and performance. It involves placing the panels under specific laboratory conditions, including:

• Exposure to an irradiance or light energy of 1,000 W per square meter
• A cell temperature of 25°C (77°F), and
• An “air mass 1.5 spectra,” or AM1.5. This imitates sunlight passing through the atmosphere at an angle of 48.19 degrees.

The standardised settings enable manufacturers to measure and report key performance metrics, making it easier to compare the power outputs of different solar panels. However, it’s important to note that the actual power output may vary in real-world scenarios due to various factors.

For example, a solar panel rated 350W will produce an average of 265kWh of electricity in the UK.

What Factors Affect Solar Panel Output?

The actual output of your solar panels will vary depending on factors like:

Orientation and Angle

The orientation and angle of the solar panels with the sun can affect their output. Ideally, you must angle and orient your solar panels to maximise exposure to the sun.

In the UK, a south-facing orientation with an angle of around 30-40 degrees is typically optimal for maximum sun exposure throughout the day.

You can still get a decent amount of power from solar panels on an east-facing or west-facing roof, but the output can vary between mornings and evenings.

The Type of Solar Panel

There are various types of solar panels, each with different performance levels and efficiencies. Common types include:

• Monocrystalline solar panels – These are made of pure silicon and feature the highest efficiency and power output. They can convert more sunlight into electricity and are suitable for maximum energy generation with a power capacity of 320 to 375 watts.
• Polycrystalline solar panels – Crafted from multiple silicon crystals melted together, they feature a lower power capacity than monocrystalline panels, ranging from 240 to 300 watts. However, they’re more cost-effective.
• Thin-film solar panels – These feature a combination of different materials and have a much lower output. They’re the cheapest, lightest, and most flexible and are usually suitable for caravans and boats.

Shade

Shadows from trees, buildings, or other structures can significantly reduce the amount of sunlight hitting the solar panels and decrease the panel’s efficiency and power output. Studies show that even partial shading can decrease efficiency by up to 50% or more.

If something casts a shade on one of the panels and reduces its output, it can decrease the electricity generation capacity of the entire array.

To identify potential issues from obstructions, perform a shading analysis before installing solar panels on your home.

High Temperature

Although solar panels can withstand sweltering weather, they work best when their temperature is as cool as possible.

High temperatures can reduce the ability of the solar cells to convert sunlight into electricity, causing the panels to lose some of their efficiency temporarily. Although they won’t stop working, the output will drop as temperatures exceed 25°C.

Location

Different regions in the UK receive different amounts of sunlight hours, which directly impacts solar panel output.

The south of the country gets more sun in general, with an average of around 128.4 watts per square meter. Regions with high levels of solar irradiance, like those with fewer clouds or those closer to the equator, also have a higher solar panel output.

Quality of the System and Installation

A solar panel system involves a complex network of electrical equipment that can malfunction or underperform if it’s of poor quality or is installed incorrectly.

The quality of the solar panels, inverters, and other components of the solar power system can affect overall efficiency and output. Improper connections can result in less power production or, at worst, start a fire.

Related solar guides:

• How many solar panels do you need?
• Smart Export Guarantee
• Can you install solar panels in a conservation area?
• Best 4kw solar system with battery storage
• Sunshine hours map UK
• Best Solar Panels
• Solar panel output calculator

How Can You Improve Solar Panel Output?

Monitor Your Solar Panels

Monitoring the performance of your solar panels can help ensure they’re generating the expected power output. You can do this by checking the solar panel meter, which records the amount of electricity your solar panels produce.

Some solar companies also offer online monitoring tools and apps that can show you how much power your panels are producing. Ensure you contact your installer if you notice any dips in performance.

Get High-Quality Solar Panels

Some solar panels are more efficient than others, so the type and quality of the solar panel will affect the electricity output.

When comparing the different solar panels in the market, ensure you consider the cost to value. Go for more efficient panels with better performance in low-light UK conditions, high power ratings, and long lifespans.

Hire A Qualified Installer

The quality or efficiency of your panels will not matter if they’re not installed correctly by a qualified and trustworthy installer.

Ensure the installer you hire is MCS-certified to guarantee adherence to recognised industry standards.

A competent installer will ensure your system produces as much power output as possible, requires little maintenance, and has a long lifespan.

Final Thoughts on Solar Panel Output

Solar panel output is the amount of electrical power the panels can produce. It can be affected by the type of panels you install, their orientation and angle, shading, ambient temperature, your location in the UK, and the quality of the system and installation.

Sources and References

• https://energysavingtrust.org.uk/advice/solar-panels/
• https://www.mdpi.com/1996-1073/16/3/1169