A guide to solar inverters

A solar system is only as good as its inverter. Canstar Blue explains what a solar inverter is, what inverter you need and how much they cost.

When you think of solar, what’s the first thing that comes to mind? Solar panels, right? Of course solar panels are very important, but they’re only one of a number of components required for rooftop solar. An equally important and often overlooked component is the inverter. Inverters are essentially the brains of a rooftop solar system – while solar panels produce electricity, it’s the inverter that makes it possible to use this power.

But does it matter which inverter you buy? Although your solar installer will have some tailored advice about the best inverter for your property, it’s always handy to have some basic knowledge yourself. In this article, Canstar Blue explains the importance of a quality inverter. We discuss what to look for and how much they cost.

What is a solar inverter?

solar inverterAn inverter is responsible for, well, inverting electricity. When the sun shines on your solar panels, electrons are released in the form of DC electricity. This electricity is either stored in a solar battery or it flows to an inverter where it’s converted into AC electricity which can be used by household appliances. Not all inverters are the same however, and the inverter you pick can have a huge impact on the overall effectiveness of your rooftop solar system. Some inverters are more efficient in converting electricity while other inverters might integrate smart communication and monitoring technologies to give users crystal-clear insights into their energy usage.

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Types of solar inverters

There are six types of inverter: String inverters, micro inverters, battery inverters, hybrid inverters, grid-tie inverters and off-grid inverters.

  • String inverters: These are the most common type of inverter. Essentially, electricity from solar panels is fed into a central inverter via multiple wires. While these are popular and affordable, string inverters are incompatible with solar batteries without an additional battery inverter.
  • Micro-Inverters: These are much smaller in size and capacity compared to standard string inverters. Instead of having one central inverter however, there’s a micro inverter installed on the back of each panel. Micro-inverters perform better than string-inverters when the panels are partly covered by cloud or shade, but micro-Inverters are considerably more expensive.
  • Battery inverters: Unlike the previous two mentioned inverters, battery inverters work specifically to convert stored DC electricity in to AC electricity.
  • Hybrid inverters: This is essentially a battery inverter and string inverter combined. Hybrid inverters are cheaper than purchasing the two inverters separately, however they tend to be slightly less efficient. Hybrid inverters can be installed even if you don’t have a solar battery so you can be ‘battery ready’.
  • Grid-tie inverters: This is a sub-group of inverter capable of matching the electricity grid’s electricity wave to allow your solar system to export electricity to the grid. Most string, hybrid and micro inverters are also grid-tie inverters.
  • Off-grid inverters: As the name suggests, these inverters are built for off-grid living and are compatible with diesel-generated electricity.

What are the best solar inverters?

fronius inverterThere are a number of different inverter brands on the market and it’s of course a bit subjective as to what’s considered ‘the best’. That being said, Fronius and SMA are arguably the two brands most associated with performance, safety and endurance. Fronius (pictured) in particular is best known for producing a variety of innovative inverters with intelligent communication and monitoring technologies.  Other popular brands include:

  • ABB: High quality and reasonably priced inverters with basic features
  • Delta: Blocky, high-efficiency inverters at a moderate to high price tag
  • Enphase: Micro-inverters. Expensive, but better performance than string inverters
  • Sungrow: Affordable and relatively high efficiency inverters. Australian company
  • Zeversolar: Cheap inverters with surprisingly high performance given the cost
  • Growatt: Affordable, bare-basic solar inverters

There are plenty other inverters on the market, but keep in mind that inverters aren’t compatible with every brand of solar panel. Your solar installer should have some recommendations, so be sure to take those on board. Whatever you choose, just make sure the inverter your purchase is up to the relevant Australian standards. You can see a list of Clean Energy Council approved inverters here.

Solar inverter price

The cost of solar inverters varies from about $900 to $2,500, depending on the size and quality of the inverter, as well as any additional features. Inverter installation will generally cost an additional $200 to $300. If you purchase the inverter as part of a solar system, you can have some of the cost rebated in the form of Small-scale Technology Certificates. You will have to bear the full cost if you’re just replacing the inverter however, so it’s important to find an inverter that will last.

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What to consider when buying an inverter

Once you find a reputable inverter brand and worked out how much it might cost, then it’s time to start thinking seriously about what is right for your home.

What size inverter should I buy?

The obvious answer is that your inverter size should match the maximum output of your solar system. So if you have a 4kW solar system, you need a 4kW inverter – simple. That said, some installers advise an undersized inverter to account for solar degradation. If you’re planning on adding more solar panels in the future, then purchase a larger inverter.

Inverter efficiency

Efficiency measures how much electricity the inverter successfully converts from DC to AC. For example, a 92% efficient inverter would waste 8% of a solar systems electricity production in the process of conversion. Most inverters have efficiencies of over 95%. Some of the best units have efficiencies around 98%.

Inverter warranty

Most inverters come with a warranty of at least 5 to 10 years, plus a 10 year warranty on the installation workmanship. Customers can usually also pay extra for an extended warranty.

Solar monitoring technology

You have probably heard about smart home technologies, but what you probably didn’t know is that it’s the inverter that makes it all possible. Solar monitoring lets you track how much electricity your solar system is producing, how charged your solar battery is and how much electricity is being fed on to the energy grid. Most reasonable-quality inverters have monitoring capabilities, but as you’d expect, leading brands like Fronius and SMA have a reputation for the most accurate and insightful monitoring systems.

How to get the most from your system

Solar panels and an inverter will set you back thousands of dollars and take years before the investment starts paying returns. But there’s a way to speed this up. Some electricity retailers have special solar deals designed to help solar customers save more from their solar. If you haven’t compared electricity retailers in some time, then there’s a chance you’re missing out. See what fellow Aussies have to say about their solar company in Canstar Blue’s satisfaction star ratings.

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