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What Is a Solar Inverter?
An inverter is a system which inverts (changes) the energy that your solar panels pick up from the sun, the direct current (DC), into alternating current (AC). AC is the current of electricity that can be used directly by your appliances or can go straight back onto the grid to be used by others.
Inverters also monitor the amount of electricity being received and outputted so that you can keep an eye on the efficiency of your panels and how much energy you are producing.
Types of Solar Inverter
There are two types of inverter. String inverters and micro inverters.
The traditional inverter is a string inverter, typically a box which is housed in the attic. Cables run from all of the solar panels into the box, where inversion takes place. String inverters are currently the most tested and most reliable.
However, string inverters have some issues. If one of your solar panels is shaded or damaged, and therefore working at a lower efficiency, then the overall output from the inverter may be reduced. Imagine a string of fairy lights, when one individual bulb is not working then none of the lights will work, string inverters can act similarly.
The newer type of inverter is called a micro inverter. Micro inverters are small boxes situated behind each individual solar panel that invert the sunlight into AC current directly at the panel. Micro inverters solve a lot of the issues found in string inverters. If one panel is not performing optimally it become obvious which panel has the issue and the overall output is not affected. They also have a longer life and up to 25 year warranties. However, as they are a newer technology, they are not yet as advanced or widely available as string inverters.
How Much Do Solar Inverters Cost?
The cost of your initial inverter, and the installation of it, should be included in the quote given by your solar panel installer. However, as solar panels have such a long life span, inverters currently are unlikely to last the same amount of time as your panels. Most string inverters come with a 10-12 year warranty, compared to the 25 year warranty of most solar panels, meaning you will probably have to replace them at some point. Your installer can offer you information on which is the best inverter and which ones they use.
You can also shop around online. Which inverter you will need depends on the size of your system. Inverters very a great deal in price but it will be around £500- £1000 for a new string inverter on an average residential system. This price may seem high but it will easily be absorbed into the continued energy bill savings that the inverter will give you.
It is harder to determine a definite price for micro inverters because it will depend on how many individual solar panels you have and what size system you have. Average prices range from about £65-85 per micro inverter box. Some companies offer packages for common system sizes. Therefore a 4kW pack, with additional accessories, could be around £1500 for 16 inverter boxes. If you have less solar panels then the price will be lower.
Leading Manufacturers of Inverters
Samil are an international company with bases in Australia, China, the UK and more. They offer micro and string inverters. Samil have named their inverter series after bodies of water (pond, river, lake) to make it easier to quickly discover which size you need. They also have case studies on their website which include residential British properties.
Kako offer a range of inverters, right up to corporate and off-grid levels. They offer two systems that would be suitable for residential purposes; the traditional Powador or the new, lighter Blueplanet.
SMA are highly recommended due to their excellent aftercare service. All SMA inverters come with access to ‘Webconnect’ which allows you to monitor your energy input/output online. SMA currently offer one micro inverter and they believe that micro is the future of solar energy.
Fronius are an American company with their UK base in Milton Keynes. They offer a range of string inverters. Fronius focus on wi-fi enabled inverters that allow you to connect the machine to an online monitoring system wirelessly.
Delta offer worldwide manufacturing and sales, along with over 40 years of experience. Delta offer a range of tried and tested string inverters, as well as a new micro inverter system. Delta also offer a range of easy monitoring options, including an app.
Solaredge offer Smart Modules along with their standard string inverters. Smart Modules work similarly to micro inverters and come with an impressive 25 year warranty.
What Is the Most Efficient Inverter?
As it stands string inverters are the most efficient. This is because they have been around for the longest time and have therefore been researched and improved to provide maximum efficiency.
However, micro inverters could be the solution to many of the problems as yet unsolved by string inverters. Currently string inverters do not get the maximum efficiency from each solar panel and if one solar panel is not performing well it can bring down the amount of electricity you receive from the whole system.
As micro inverters are still relatively new there is still a lot of room for improvement in the way they operate. They are also still a fairly expensive technology, however their long life span may justify this. Most installers are still using string inverter systems as standard. This could change in the near future as micro inverter systems become more efficient and less expensive.
What Inverter Should You Choose?
You should not have to buy your inverter separately when you first install your solar panels. The inverter should be included in the overall quote from your installation company. However, it is worth asking the company which type of inverter they use and whether you have the choice of a string or micro inverter. Currently string inverters are the more stable choice but the technology used in micro inverters is rapidly improving.
String inverters have a general lifespan between 10-15 years, a lot shorter than the potential life of your solar panels. Therefore, you should look ahead to decide whether you would like to replace your inverter with another string model or if you would like to invest in new, longer lasting, micro technology. As micro inverters continue to become more efficient and reduce in price, they could very well become the standard in solar PV systems within the near future.