A solar inverter or PV inverter is a vital component of a solar photovoltaic (PV) system and is usually included in the cost and installation of your system.

Choosing the right solar inverter for your home

There are various factors to consider when deciding what sort of solar inverter is the right one for your home, including how it works, prices and savings, and the type of inverter. A reputable installation company will be able to provide further expert advice.

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What is a solar inverter?

A solar inverter is an electrical converter which changes the direct current (DC) electricity captured by solar panels, into alternating current (AC), which is the standard flow of electricity required for electrical circuits and domestic appliances.

How does it work?

Solar inverters work by doing the following:

1) DC electricity is channeled through a transformer.

2) The transformer lowers the voltage and changes to AC.

3) The DC runs through two or more transistors.

4) These are rapidly turned on an off to feed the two different sides of the transformer.

Solar inverter costs and savings

The type of inverter that you need will depend on the system size required by your property. Although prices can vary greatly, a new string inverter for a typical residential home would be approximately £500-£1,000. The inverter often forms part of the complete solar PV system and the type of inverter chosen will affect the overall installation cost.

The initial quote from your solar panel installer should include the cost and installation of the solar inverter. But because of the impressive lifespan of solar panels, it’s unlikely that the solar inverter will last as long as they do, meaning it will most probably need to be replaced at some point.

The savings that can be expected from using a specific type of solar inverter depends largely on the size of the system, the amount of energy it produces and how much electricity you use. A qualified installer will be able to advise you on these factors in more detail.

Calculating efficiency

The more an inverter costs, the greater the efficiency levels will be. However, even lower cost models will achieve a conversion rate of around 93%. 

How long will it last?

Due to the constant function required to convert the electricity current, your solar inverter is likely to need replacing approximately every 10 to 15 years.

Types of solar inverter

There are three main types of solar inverter – string inverters, microinverters and power optimisers:

1. String inverters

String inverters are the oldest form of inverter, using a proven technology that has been in use for decades. Solar panels are arranged into groups or rows, with each panel installed on a ‘string’. Multiple strings can be connected to a single inverter, which transforms the DC electricity produced by the panels into appliance-friendly AC electricity.

The downside of string inverters is that if the performance of one panel is reduced – for example by damage or shading, the performance of the whole array can be affected.

2. Micro inverters

Micro inverters are becoming a popular choice in residential solar systems. These are fitted to each individual solar panel and convert DC to AC on the roof, removing the necessity of a separate inverter.

Because the conversion is performed this way, if one or more panels are affected by shade then it doesn’t have an impact on the panels that are still in sunlight. It’s also possible to monitor performance levels of every single solar panel.

Micro inverters are often considered as a way to install more solar panels on a roof. Panels that may be in partial shade for some of the day will not affect the performance of the other panels that remain in sunlight more of the time.

Micro inverters are still a relatively new technology and are generally more expensive than other inverter types, however, this additional cost may be offset by increased energy production.

3. Power optimisers

Offering many of the benefits of microinverters, but slightly less expensive, power optimisers are also located on each individual panel. But instead of converting DC to AC at roof level, they move the DC to a string inverter. With power optimisers, you should be able to monitor the performance of each panel via an online portal.

Hybrid inverters

These inverters form the basis of a hybrid solar PV energy system. During times when surplus energy is generated, the hybrid solar system offers the option of selling excess electricity back to the grid or storing the renewable energy in a battery.

The solar storage battery can then provide power. This will require the hybrid inverter and battery to be installed with the necessary software and changeover switches. These often don’t come as standard so be certain to ask your installer to include them in your quote.

How to avoid a bad solar inverter

There’s a host of factors to take into account when choosing which inverter will best suit your system. Which type will provide the most effective functionality? What materials is it manufactured from? Has it met appropriate certification and standards?

If you have any questions or doubts about the solar inverter that you are considering, please seek independent advice. 

How to repair a solar inverter

The first step to take if you think you have a problem with your solar inverter is to check if it’s showing a red or green light. If working properly, most inverters will display a solid green light during the day, when producing electricity, and a red light when in sleep mode during the night.

However, if it is showing a solid red light during the day then it’s unlikely that it is functioning correctly. You can refer to your user manual to identify what a specific error code means and to determine whether you are able to correct it yourself or if you need to contact a professional.

You should always choose a reputable installation company to inspect or fit your solar inverter. All HIES Accredited Installers are continually vetted in many areas in order to give consumers trust, confidence and peace of mind. .

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