What is Solar Panel Efficiency?
When it comes down to your solar panel installation, of course, you want to make sure you are installing the best solar panel there is. In general, the three most important factors to consider when choosing a solar panel are its efficiency, maximum power output and warranty.
Solar panel efficiency is the measure of how much sunlight a solar panel can convert into electricity. Different brands and types of solar panels will have different panel efficiency. The majority of residential solar panels typically have an efficiency of 15-18%, although premium modules can reach over 21%.
Why Is Solar Panel Efficiency Important?
It’s a no-brainer that the more efficient your solar panels are the more solar energy your PV system is going to produce. And the more energy your Solar panel system is generating means the less energy from the Grid you’ll have to buy.
For properties with smaller roofs or land availability, more efficient solar panels still make solar energy a viable option. As a larger panel wattage combined with efficient solar cells, should be enough to still power your home from the sun.
Who makes the most efficient solar panels?
These are the most efficient solar panels for home solar installations as of 2023. Our team have collated the top brands across the solar industry and found their most efficient solar modules to put head-to-head.
When exploring solar panels, the panel efficiency rating is always listed on the datasheet. As you can see any solar panel with a maximum efficiency of over 20% is a premium solar panel.
Calculating Solar Panel Efficiency?
To calculate a solar panel’s efficiency, scientists test the panel in controlled lab conditions. The Standard Test Conditions (STC) for calculating solar panel efficiency aims to see how much solar energy the cells can convert to electricity in a simulated clear 25°C summer’s day, with an irradiance of 1000 W/m2. However, the given maximum efficiency level is not necessarily what the panels will achieve in real-life conditions. Especially as we know the weather isn’t always consistent and certainly not always sunny in the UK.
Fortunately, some solar panels are starting to come with a Performance Test Conditions (PTC) rating. A PTC is a more accurate measure of the efficiency of a solar panel, as it tells you how the solar panel will perform in a variety of climates and conditions. Some manufacturers even go a step further and look into the “system PTC rating”. This takes into account the efficiency of the solar inverter as well as the solar panel. As your solar panel system’s efficiency is in reality a sum of all its components. So even if you have the most efficient solar panel, an inefficient inverter will draw your overall efficiency down.
Solar Panel Efficiency Calculator
What factors impact a Solar Panel's efficiency?
There are three main types of solar cells used in the manufacturing of solar panels: Monocrystalline, Polycrystalline and Thin-Film. Each type of solar cell has a different level of efficiency.
- Monocrystalline solar panels are the most efficient type of solar panels. This is because the cells are manufactured from just one single piece of silicon. Although they are the most efficient at converting sunlight into electricity, they are also the most expensive.
- Polycrystalline solar panels are made up of multiple fragments of silicon crystal melted together. As the silicon isn’t as pure, this makes them slightly less efficient than monocrystalline solar panels, however more affordable.
- Thin-film solar cells are both flexible and low in profile. Manufactured from just a thin layer of semi-conducting material, on top of electrical components, thin-film panels are the least efficient out of all three. However, as they are lightweight and more flexible they can be used for more diverse applications.
If you look closely at the surface of a solar panel, you will see a bunch of thin lines. These are a series of copper or aluminium wires, that conduct electricity. Solar panels which have thinner busbars will be more efficient, as there will be a reduce amount of shading on the cell, allowing the panel to absorb more light. Solar Panel manufacturers which use multi-busbar technology, which utilises multiple ultra-thin busbars increase the overall solar panel’s efficiency. Some solar brands, for example, Sunpower, now use Interdigitated Back Contact cells (IBC), which removes all the busbars and wiring from the face of the solar panel to the back, so that more sunlight can be absorbed.
Do solar panels lose efficiency over time?
Solar panel efficiency does decrease over time due to the natural degradation of the solar cells. On average the efficiency of a solar panel falls by 0.5% per year. However, most manufacturers provide a 25-year performance or “linear output” warranty. This guarantees that the solar panel’s output won’t drop below 85% of its original efficiency within the first 25 years.
Visit our other content to find out more information on how long solar panels last.
What else reduces Solar Panel Efficiency?
Nearby obstructions such as chimneys or trees, can provide enough shade on a solar panel to impact it’s efficiency by up to 50%. Before installing a Solar PV system it is important for your chosen installer to carry out a shading analysis to evaluate any potential issues.
In the UK, to get the most amount of sunlight, it is always recommended that your solar panels are installed onto a south-facing roof, at a pitch of 30-45 degrees. However, as we know, these ideal conditions can’t always be met. It is important that your energy advisor designs the best possible layout that matches your energy needs.
A dirty or damaged solar panel caused by pesky birds or nearby trees, can reduce your solar panel system’s overall efficiency. It is important to keep your PV system well maintained, to check for any irregularities in your energy production, to keep your solar panels clean, and protect your system from any birds that may nest underneath them.
Although many may think Solar panels are less efficient in the winter, it is in-fact extreme heat that can do more damage to your solar panels. A well ventilated solar panel will always operate more efficiently than one that isn’t, simply because when the surface of the solar panel gets hotter, its efficiency drops. It is for this reason why on-roof solar panels are more efficient compared to solar tiles, and integrated solar panels. Solar panels actually operated best in cold, yet sunny conditions.
Visit our other blog for more information on what conditions are required for optimal efficiency in a solar panel.
Are premium efficiency solar panels right for you?
So if you have limited space for your solar panels, partial shading or a roof which isn’t ideal, you may want to consider one of the most efficient solar panels on our list above. Nevertheless, whilst efficient solar panels do come with some great advantages, the chances are they are probably not required for most homeowners. This is where a survey comes into play. Here at Deege Solar we offer free remote assessments and designs, to find you the perfect solar panel system which is both right for your home and pocket.
If you are looking to get the most efficient solar panels installed, no problem at all. Here at Deege Solar we install a variety of solar panels. Offering a selection of the most reliable, efficient and cost-effective panels on the UK market. Simply click enquire now and fill out of short form, or contact us on 01322 479369 to speak to an energy advisor.