What is a solar inverter?
An alternative current (AC) is the modern type of electricity your circuit board uses to power your home and domestic appliances. In the past, electricity was delivered using a direct current (DC) format but this changed in the late 1800s. Some appliances like solar panels, electric vehicles, LED lights and computers still use a direct current.
Since solar panels don’t produce AC energy on their own, they need something to change the direct current they generate into an alternative current that’s useable for the majority of our purposes. A solar inverter converts a DC input into an AC output.
How does a solar inverter work?
The direct current from your solar panels is channelled through a transformer which changes it to an alternate current and lowers the electricity’s voltage. The direct current goes through two or three more transistors and the energy is bounced between the two sides of the transformer.
The job of a solar inverter is to trick the transformer into thinking the DC input it’s getting is actually an AC one by forcing the electrical current to behave like one. Smart stuff, right?
What’s the difference between single phase and three phase inverter?
In short, a single phase electrical supply is ‘smaller’ than a three phase electrical supply. A single phase supply will be able to handle less of an electrical load than a three phase system.
Generally speaking, residential properties in the UK have a single phase connection and commercial buildings have a three-phase connection. Rural villages and farms typically also have a single phase connection. This isn’t always the case but it’s a good starting point.
Whether you need a single or three phase inverter depends on the electrical supply of your property. If you have a single phase supply then you need a single phase inverter and a three phase system will require a three phase inverter.
The best way to tell if your property has a single or three phase supply is by looking at your electrical fuse (also called a supply or service head). A single phase system will have one fuse and a three phase system will have three 100 amp fuses. Any installer or electrician will be able to find out and confirm this for you.
The 3 main types of solar inverters
- String inverters
These are the most common type of inverter for residential properties and you only need one for each solar installation. They’re called string inverters because they’re connected to a string of solar panels. This is in contrast to the next type of inverter which is installed to each individual panel rather than the set. - Micro-inverters
This is an intelligent type of inverter that allows each panel to work independently of the rest. When a string inverter is installed, if one PV panel starts performing worse than the others – the whole system suffers. A micro-inverter manages each panel individually so this doesn’t happen. - Hybrid inverters
Hybrid inverters will convert the DC input from both your solar array and your battery units. While other inverters are ‘one-way’ (they convert DC into AC and that’s it) a hybrid inverter can convert an AC input from the grid or a generator and turn it into a DC current for battery storage.
Which solar inverter is the best?
This will depend on the rest of the system you have or are planning to install. If you are looking to implement battery storage, then a hybrid inverter would be beneficial. If you live somewhere shaded by trees or lacking in sunlight, then a micro-inverter will help to mitigate any loss in performance. String inverters are typically the cheapest and therefore the best option on a budget. Discuss this with your installer to figure out your options.
Can a solar inverter be overloaded?
Yes. When your solar PV system generates more electricity than your inverter can handle – it’s called oversizing. Generally, you want your PV system to output as much as your invert can take and not more. This will reduce waste and and improve your system’s efficiency.
However, inverters can typically handle up to 133% more energy than they’re designed to. If you have a 5kW inverter then this means it can actually process 6.6kW of electricity from your PV system. A SolarEdge inverter might be able to oversize up to 155% depending on the model.
Your installer shouldn’t install a system that’s inadequately protected from faults, threats or overloads but they might install an inverter with regular oversizing in mind if it’s safe to do so.
Can you repair a solar inverter?
Yes. In the first instance, you should contact your original installer and ask them to repair it for you. Your installers may also provide you a guarantee period but it’s possible your inverter stops working properly after it’s already expired.
It’s possible your installer isn’t contracting anymore so you’ll have to outsource this work to somebody else. We do inverter repairs and see this time and time again.
Summary
Solar inverters are a crucial component of any solar PV system as they convert the direct current generated from your solar panels into an alternative current you can use at home. You might opt for a string, micro or hybrid inverter depending on the rest of your set up – there’s pros and cons to all of them.
If you’re looking to learn more about solar energy read more of our articles or get in touch to discuss your own solar installation.
