Which Are The Best Solar Inverters?

So you’ve got quotes for a few different solar power systems. Everyone says they sell the best solar inverter – no surprises there. So how do you decide what brand and model to select? Our solar inverter reviews can help you choose what’s best for you – these reviews offer unbiased information based on the feedback of thousands of Australians using different makes and inverter models.

However, it’s good to first have some background information on what this important device does, the major manufacturers that produce them and various other aspects to consider – and this guide will provide you with that information.

All the solar power produced by your panels will pass through your inverter, and the device also contains important safety shutdown electronics called Anti-Islanding Protection. For this and other reasons, it is critical you choose a solar inverter up to the job and one that offers the best performance for your money. 

Solar Inverter Brands

I’m guessing  you don’t know one brand of solar inverter from another – you certainly aren’t alone. The simplest, quickest way I can think of how to describe how each brand stacks up is to compare them to cars – because I’m also guessing most of you will know the difference between a Mercedes, a Holden and a Hyundai.

If you’re in a hurry and you don’t want to “geek out” over the technicalities  – this chart I created will teach you enough to be dangerous when talking to shonky sales people or evaluating quotes:

If Solar Inverters Were Cars…

  • Fronius inverter

    BMW

    •  Top quality
    •  European made
    •  Expensive
    •  Lots of features
    •  Great Performance
    •  Fronius reviews

  • SMA inverter

    Mercedes

    •  Good quality
    •  German & Chinese made
    •  Expensive
    •  Long & Proud History
    •  Efficient
    •  SMA reviews

  • SolarEdge inverter

    Lexus

    •  High quality
    •  Innovative
    •  Expensive
    •  Lots to play with
    •  Great Hybrid models
    •  SolarEdge reviews

  • Enphase microinverters

    Mini

    •  Top Quality
    •  Innovative
    •  Teeny Tiny
    •  You either love ‘em
      or hate ‘em
    •  Enphase reviews
       

  • ABB inverters

    Ford

    • Acquired by FIMER
    •  Solid Company
    •  Popular in Europe
    •  Mid-range choice
    •  ABB reviews

  • Delta inverters

    Volvo

    •  Built like a tank
    •  Looks like a tank
    •  Safe choice
    •  European Heritage
    •  Long history
    •  Delta reviews

  • Sungrow inverter

    Hyundai

    •  Cheap
    •  Reliable
    •  Well Supported
    •  Unpopular with hipsters
    •  Sungrow reviews

  • Goodwe inverter

    kia

    •  Cheap
    •  But quite good
    •  Made in Asia
    •  Have improved
    •  Goodwe reviews

You can read more about the above brands (and many others), along with feedback from Australians who have had them installed in our solar inverter reviews section.

Now let’s get technical.

If – after all that – you are still yearning for a deeper understanding, then continue reading…

Types Of Solar Inverters

The following describes each type:

a) String Inverters

This is the most common type of inverter for residential use. All the solar inverters above (apart from Enphase) are string inverters. On a residential solar power system you generally have one per installation. It is called a string inverter because you connect strings of solar panels to it. 

b) Central Inverters

These are massive inverters used for solar systems in the hundreds of kilowatts or even megawatts of capacity. They look like big metal cabinets and can handle up to 500kW capacity per enclosure. You won’t find these as part of home installs; they are only used for large commercial installations or utility scale solar farms.

c) Microinverters

Microinverters are  tiny solar inverters about the size of a paperback book. You need one per solar panel. You can read about the advantages of microinverters here, the main one being is they optimise each panel individually, delivering more energy. Microinverters can be particularly useful if you have partial shade conditions. The only microinverter in the list above is Enphase.

d) Hybrid Inverters

Also known as multi-mode inverters, a hybrid inverter enables you to plug batteries into your solar power system. The hybrid inverter interfaces with the battery using a technique called ‘DC coupling‘, and its electronics coordinate the charging and discharging of the battery.

There is a fairly limited choice of hybrid inverters on the Australian market right now. We’ve listed all the ones we know about on this hybrid inverter comparison table. Check it out if you are considering buying batteries with your solar power system.

e) Battery inverters

If you want to retrofit batteries to your solar power system, or simply keep your battery system separate from your solar panels (i.e. not going through the same inverter), then a separate battery inverter is a good choice. This simply converts your battery power into 230V AC and feeds it into your switchboard instead of grid power where possible.

What To Look For In A Good Solar Inverter

a) Can it be used in Australia and is it approved?

The first thing to look for when choosing a solar inverter is to see if it complies with the relevant Australian Standard (AS4777). You can quickly do this by checking out the Clean Energy Council’s approved products list.

All certified grid connected solar  inverters should be on this list. If one you’re considering isn’t – don’t buy it it (unless you live for danger!). The other reason for buying a solar inverter on the approved products list in the case of a full solar power system purchase is in order for your system to be eligible for Australia’s major solar subsidy, it must be on the list at the time of installation.

It’s also worth looking at the company behind the product – how long have they been around and what is their expertise?

b) How much should I pay?

This is a difficult question to answer, as grid connected inverters are mostly offered as part of a solar power system package. This component can represent around 20% of the cost of a system.

A 3kW solar inverter will cost around $800 (retail) for a budget brand such as ZeverSolar or Sungrow, and up to $1,500 for a premium model from Fronius or SMA.

5kW solar inverter costs start at $1,000 for budget, single-phase models and up to $2,000 for the premium single-phase models.  5kW is the most popular size and can accept up to 6.6kW of panels. I explain more about this below.

If you want a 3-phase, 5kW inverter you should add about $400 to those prices.

But whatever you do,  never buy the cheapest solar inverter on the market! The really cheap products have no chance of lasting 15 years plus in Australia. Trust me on this. It is difficult and expensive to design and manufacture a good solar inverter that will endure; particularly in Australia’s often harsh conditions. Never buy a bottom of the range product from a no-name brand. It is false economy as it just won’t last (rather like the companies selling them!).

c) What solar inverter size (capacity) is best to buy?

There is often some confusion around this question.

In general, at a minimum the inverter needs to be able to handle the maximum power that your solar power system can generate. That usually means that if you want a 5kW solar power system, you get 5kW of panels and a 5kW solar inverter to suit. Simple eh? Actually, it can get a little more complicated than that. Let me explain.

Because of system losses in the panels, your solar inverter can actually be rated at up to 25% less (in AC kW) than your panel array – in some situations.  Confused? So were a number of installers for some time! The Clean Energy Council guidelines for solar inverter sizing changed a while back, and I provide a detailed explanation of when ‘undersized’ inverters are allowed here.

A final word of caution:  Be aware that solar inverters are rated in “DC input” and “AC output” terms. Make sure yours is also rated to suit the output of your solar panels in DC! (The previous link explains how to check this)

Some retailers will offer you a larger solar inverter so you can add extra panels at a later date. Before making a decision to buy one of these, you need to consider the following:

  • Do I have enough space on my roof to put new solar panels? (kind of pointless otherwise)
  • Will my current panels be available in the future?

Solar panel technology is changing so rapidly that your current solar panels may not be available when you want to upgrade. Your inverter may not be able to accommodate the mismatch of solar panels, which may mean you’ll need to buy a new one. A way to overcome this potential problem is to perhaps consider a multi-string or a MMPT expandable solar inverter (see below).

In general, the best advice is to install as many solar panels as you can afford (and fit on your roof), and purchase a solar inverter to suit the maximum power of the system.

What about the physical size of the solar inverter?

Grid connected inverters come in a variety of shapes, sizes and weight. The smallest string inverters are around the size of a large briefcase. The larger are around the size of a small travel case.

They are generally located as near as practicable to your electricity meter and should always be located in the shade for best performance. The best advice is to have a look at the solar inverter (or check out its specification sheet) and see whether it will fit near your electricity meter and what it will look like when installed.

d) Is it weather-proof?

Some grid connected inverters are weather-proof so they can be located in areas that may have some exposure to the elements. Other solar inverters are not weather-proof and may require the addition of a weather-proof cage (at extra cost to you) if the inverter is to be exposed to weather. As a general rule, your solar inverter is a box of sensitive electronics and the better it is protected from heat and weather, the better it will perform and the longer it will last.

Check this out aspect on the specification sheets or ask your retailer where they intend to install your solar inverter.

e) How good is the warranty?

Typically, grid connected inverters have a lifespan ranging from 10 to 20 years. You should expect most good quality units to last 10 years minimum.

Solar inverters have warranties ranging from 5 to 12 years with an increasing number of manufacturers offering pay for service warranty extension. Most retailers are now offering 8 to 10 years warranty. Obviously, the longer the warranty the more protection you have.

So check out the warranty of the unit and balance this against other features of your system to help you make an informed decision as to which is the best solar inverter for you.

f) Is the inverter expandable?

This is an important consideration if you’re intending to expand your solar power system in future.

The best solution at present would be to consider a multiple MPPT (Maximum Power Point Tracking) inverter. These solar inverters have multiple MPPT trackers allowing you to add additional solar PV arrays at a later date or to install arrays at different orientations. This will enable you to easily add a new string of panels (even if the new panels are not exactly the same as the original modules) to your current system.

Some solar panels have a small MPPT inverter attached to the rear of the module, typically called micro inverters. These potentially enable different models of solar panel to incorporated in the same solar power system, overcome shading issues and make individual solar panel monitoring possible. There is an rapidly increasing trend towards these products in the USA and they are being more widely used in Australia.

g) What about the display?

Most solar inverters have display lights indicating whether the unit is on, off or in standby. They can also have digital displays (often scrolling displays) that indicate some  or all of the following information:

  • the amount of energy (kilowatt hours) you have generated on a daily basis,
  • the amount of electricity (kilowatt hours) you have produced since the unit was installed,
  • the amount of power (kilowatts) the unit is currently generating,
  • the number of hours the unit has been producing power,

Some of this information (e.g the total amount of energy generated) is also available on your meter.

Some meters also offer a data-logging feature enabling you to download information to a computer, or transmit it over Bluetooth or your Wi Fi network. This means you can see your power information on your PC, smartphone or on a special in-home display.

I personally don’t want to look in the meter box (or wait for the bill) to see if my system is performing properly. I want to have a remote monitor in the house that I can check every day. So I think remote monitoring / data logging is a must.

If your supplier wants to charge you more than about $250 for remote monitoring, then you may want to consider doing it yourself.

h) How efficient is a grid connected inverter?

Inverter efficiency is a measure of how well a device converts the electricity it receives from the solar panels into power available to your home or to export to the mains electricity grid. Most grid connected transformer based solar inverters (very, very few of these are sold these days) have an efficiency of around 93% or better, while transformerless devices are typically around 95% or better.

Efficiency would only be a factor if two similar solar inverters had significantly different efficiency.

How To Spot A Bad Solar Inverter

Most solar inverters supplied by reputable retailers in Australia are OK. But there are some horrible devices that have somehow manage to pass Australian compliance testing.

Before you consider buying a very cheap solar inverter – check out my ever growing list of solar inverter reviews. These reviews are submitted by Australians who have owned the inverter for at least 12 months. If there are lots of 1 and 2 star reviews, this usually means the components are failing in the first 12 months. Not a good sign! 

Next, have a look at my solar inverter comparison chart. It compares independent efficiency measurements of lots of models. A very low efficiency is a bad sign.

It’s also worth checking some of the forums (such as Whirlpool) that discuss such topics.

Also, walk away if there is no written warranty offered on the solar inverter or no specification sheet is supplied. Make sure the organisation issuing the warranty has an Australian office – you don’t want to be calling Shanghai (or Munich) to get a new one!

>>Next: What about these new fangled Micro Inverters? >>

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