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How we review solar panels: Our methodology for testing and rating solar panels

With the vast range of solar panel options on the market, choosing the right one can be challenging. This is why our professionals have taken the task on for you. They have carefully evaluated and graded many brands and types of solar panels. This allows you to rapidly gauge the quality and comprehensiveness of a product, helping you make a more informed decision.

Therefore, to ensure the utmost thoroughness in our solar panel reviews, we monitor and evaluate 36 distinct parameters. The performance of a panel in these parameters determines its overall score and forms the basis of our recommendation.

Each of the parameters we’ve tested falls within one of the following categories:

  • Performance and features
  • Provider/installer performance
  • Value for money
  • Customer experience

We proportionally adjust the scoring of each factor according to its significance in determining the best solar panel. For instance, we perceive the efficiency of a panel as more critical than its aesthetic appeal, so the efficiency score will hold more weight in the overall result. This doesn’t imply that aesthetics aren’t important, but we’d prefer a solar panel to deliver superior power output than simply look good on a rooftop.

Solar panel review stats

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The solar panel features we prioritise

We think the critical determinants of a solar panel’s quality are:

  • Energy efficiency
  • Materials
  • Durability and build quality
  • Aesthetic appeal
  • Manufacturer 
  • Cost
  • Warranty

Energy efficiency

The energy efficiency of a solar panel is important because it determines how much sunlight the panel can convert into usable electricity. A more efficient panel can generate more electricity from the same amount of sunlight than a less efficient panel. This means that with higher-efficiency panels, you may need fewer units to generate the same amount of power, which can save space and potentially reduce installation costs.

Higher-efficiency panels tend to be more expensive, so there’s a trade-off between efficiency and cost that must be considered.


The materials used in solar panels directly influence their efficiency, durability, cost, and environmental impact.

The most common material is silicon due to its excellent semiconducting properties, and several types are used to manufacture panels. The main types are monocrystalline silicon cells, regarded as being highly efficient but more expensive, and polycrystalline silicon cells, which are less efficient but also less costly. The materials used for the panel’s construction, including the glass, frame, and backing, must also be robust and durable.

The type and quality of materials used also affect the cost of solar panel. High-quality materials often lead to better performance and longevity but also increase the panel’s price.

We also consider the environmental impact of the materials used. Some types use materials that are harmful to the environment if not handled properly. For instance, thin-film solar panels often contain a small amount of cadmium, a toxic heavy metal. However, manufacturers are required to handle and dispose of these materials safely to minimise environmental harm.

Durability and build quality

Solar panels are a long-term investment, often with warranties lasting 25 years or more. If a panel isn’t built to last, it may not perform optimally over its intended lifespan, reducing the return on investment. Poorly constructed panels can also present safety hazards like electrical shorts or fire risks. 

Solar panels naturally degrade and lose efficiency over time. However, panels with high build quality and durability degrade slower, maintaining higher efficiency and power output throughout their lifespan.

Aesthetic appeal

While a solar panel’s aesthetic qualities are less important than energy efficiency or durability, our experts still factor this into the evaluation.  

In residential settings, homeowners often prefer solar installations that blend seamlessly with their existing architecture to maintain the visual appeal of their property. Solar manufacturers are aware of these preferences and have developed a variety of styles, colours, and designs, including solar panels that can integrate into roofing materials or windows, to meet this demand for aesthetically pleasing options.

Manufacturer’s reputation

The solar panel manufacturer directly influences their quality, performance, and reliability. Reputable manufacturers typically maintain rigorous quality control standards, ensuring their panels are well-built and less likely to have defects. This directly impacts the longevity and efficiency of the panels.

Moreover, manufacturers with a strong track record of innovation often produce panels with higher efficiencies and better performance characteristics. They may also be at the forefront of developing or improving new technologies.

The warranty and after-sales service are crucial aspects to consider. Established manufacturers often offer more comprehensive warranties and dependable customer service, which can provide peace of mind to the panel owner.


Installing a solar system is a significant upfront investment, which includes the panels, the inverter, batteries, installation and any potential grid connection fees. Therefore, the lower the cost, the more accessible solar energy systems become to a wider range of individuals.

The cost also impacts the payback period – the time it takes for energy savings to equal the system’s total cost. If the cost of the panels and the associated installation and maintenance expenses are high, it will take longer to recoup the initial investment through energy savings.

However, our experts balance cost considerations with quality, performance, and the manufacturer’s warranty. Lower-cost panels may not provide the same durability or efficiency as more expensive options, potentially leading to lower performance or higher maintenance costs in the long run.


The product warranty protects you if there are defects in the solar panels due to manufacturing errors or material issues. These defects can impact the performance and longevity of your solar panels. 

Most solar panel manufacturers also offer a performance warranty that guarantees a certain output level for a specified period, typically 25 years. This warranty assures that the panels will not degrade faster than expected.

We place a high value on warranties, as they can save you from unexpected replacement or repair costs and indicate the manufacturer has confidence in the durability and longevity of their product. It can be a sign of high-quality panels.

You can read more about our commitment to editorial impartiality and our editorial code on our About Us page.

Katharine Allison

Energy Saving Writer

As Independent Advisor’s energy saving expert, Katharine, a keen advocate for sustainability, is an authority on solar panels, double glazing, and cutting-edge renewable energy technologies. Her dedication merges with a commitment to enlighten and steer readers toward embracing eco-friendly solutions and the latest trends in sustainability.

With over 10 years of experience, she has worked with some of the UK’s leading companies and publications, including the Federation of Master Builders, Architectural Digest, and Denon Construction. 

Katharine is particularly passionate about consumer causes and animal welfare and has art, philosophy, and psychology degrees. She lives with her sled dogs in East Sussex.