Understanding solar panel efficiency

Solar is more affordable than ever, and renewable technology is continuing to improve year after year to give us greater efficiency.

When investing in new solar panels, you obviously want to be choosing a solar panel that gives you the best return on investment. The two main considerations you will need to bear in mind are solar panel efficiency and maximum power output.

Solar panel efficiency is calculated by measuring how much of the sunlight that the solar panels absorb is actually turned into electricity. Different solar panel manufacturers have different levels of solar panel efficiency so by choosing a solar panel with better efficiency you may find a better return on investment, although this could depend on the cost of the initial investment. Some options can reach over 21% efficiency, although most solar panels operate around 15 to 18% efficiency.

To help you understand solar panel efficiency, our friendly team of Devon solar panel installers have put together a guide so you can learn more.

The importance of solar panel efficiency

• Reaching a Return on Investment
  A more efficient solar panel will allow you to generate more energy per square foot. This can help reduce the energy you will need from the grid so allowing you to see a more rapid return on investment. We will be able to choose the best solar panels for your Devon property for your budget so giving you peace of mind that you have the right choice for you.
  
  
• Making use of limited space
  If you have a limited amount of space to install solar panels, more efficient solar panels can make solar energy a far more viable option as you should still be able to see a good return on investment even with a small installation.
  
  

Who is leading the field in 2022 for solar panel efficiency?

In 2022 the most efficient solar panels were being produced by SunPower with a range of other options producing over 20% efficiency. We appreciate that you will want the latest and greatest solar panel technology for your home, so our installers are constantly looking for new solar panel products that offer better results for your home in Devon or the surrounding areas.

How to calculate solar panel efficiency?

As so many factors can change solar panel efficiency results, each solar panel is tested within a controlled lab setting. Standard Test Conditions for solar panel efficiency simulate the amount of sun a solar panel would receive on a clear day in summer at 25 degrees centigrade. As efficiency is calculated in such ideal circumstances it will mean you will most likely not see such numbers in real-world situations.

As many of us in the UK are generally greeted each morning as we pull back the curtains with an overcast sky, there is thankfully an alternative test known as Performance Test Conditions (PTC). With PTC it allows you to see the performance of solar panels in a range of different situations so you can calculate what you could expect in return. There are even some tests that include solar panel inverter efficiency so that you get a complete idea of what energy will actually be generated. When it comes to the amount of energy generated from solar panels, Devon is one of the best areas in the UK to generate energy.

Why are some solar panels far more efficient?

• Cell Type
  Inside solar panels there are three main varieties of solar cells:
  
  • Monocrystalline
    When it comes to efficiency, monocrystalline truly excels, which is due to the cells being constructed from a singular piece of silicon. This efficiency however does come at a premium cost although all the top solar panels for efficiency are monocrystalline.
    
    
  • Polycrystalline
    Not as efficient as monocrystalline, but more affordable, polycrystalline is constructed from silicon crystal fragments that are then combined together to form a cell.
    
    
  • Thin film
    The least efficient of the three main cell types, thin-film uses a thin film of a semiconducting material, which is then placed on top of the electrical workings below. Although not as efficient, thin-film solar cells offer fantastic flexibility especially due to their lightweight properties.
    
    
    
• Conductive Wiring
  Running throughout a solar panel are various conductive copper or aluminium wires. The thinner the wiring or ‘busbars’, the more efficient the panels as the busbars will create less shade onto the solar cell so allowing for more light to be collected. Some solar panels are now even putting all the wiring and busbars behind the panel so as not to block any of the light.
  
  
• Solar Panel Backing
  The backing of a solar panel can surprisingly cause a change in efficiency just due to the colour. For example, a black backing can attract more sun that can overheat the panel so reducing solar panel efficiency. Some solar panels now have transparent and reflective backing that allows the solar panels to generate extra power.
  
  

Will solar panels become less efficient over time?

Over time solar cells will naturally degrade, even if you buy the best solar panels on the market. This means that over time the efficiency of your solar panels will, unfortunately, decrease by around 0.5% per year. It is worth checking if your solar panels come with a warranty that protects you if your solar panel drops below 85% of the initial efficiency after 25 years have passed. Our Devon solar panel installers are always on the lookout for solar panels that minimise degradation to give you a solution that is built to last.

How your scenario affects solar panel efficiency?

• Roof Shading
  If your roof is hidden behind roofs, chimneys or trees, it can mean that your solar panel efficiency can be negatively affected by up to 50%. Before even commencing installation, we at Lumos Solar will assess the viability of solar panels and if they are worth the investment for your property.
  
  
• Panel Placement
  To be able to make the most of the sun that we get in the UK, it is preferable for solar panels to be fitted on south-facing roofs at a pitch of between 30 to 45 degrees; however, this is not always possible but our friendly team at Lumos Solar will be able to walk you through the available options.
  
  
• Maintenance
  Over time there is the potential for dirt to accumulate on your panels as well as the possibility for damage to occur. The main culprits for causing dirt and damage to solar panels have to be birds and trees; however, most of these issues can be rectified either by cleaning your panels or hiring a professional to carry out general maintenance.
  
  
• Weather
  This can go without saying, but the weather will without a doubt affect solar panel efficiency, including some ways you may not have even considered. Although summer months have more sunlight hours, you can find that during hot days that the solar panel efficiency can in fact drop. This is due to the hotter the solar panels get, the less efficient the panels will be. Cold but sunny conditions will in fact grant you the best solar panel efficiency.
  
  

Is it worthwhile paying for premium solar panels?

More often than not, premium alternatives are not necessary for most homeowners. Premium solar panels are most likely going to be an option to consider in the event of partial roof shading or a small area of the roof. Our friendly team at Lumos Solar will happily walk you through the options available to you in order to ensure you find solar panels for your Devon home that you are happy with.