Micro Inverters and AC Solar Panels: The Future of Solar Power?

By Finn Peacock, Chartered Electrical Engineer, Fact Checked By Ronald Brakels

(Micro inverters are just one form of what’s known as “PLO” – Panel Level Optimisation. You can learn more about other types of Panel Level Optimisation here.)

In the beginning, there were solar panels that produced electricity as Direct Current (DC) – the same kind of electricity that you get out of batteries.

To make that electricity useful for powering appliances or connecting to the grid, it was converted to Alternating Current (AC) using a big box of electronics called an inverter.

In grid connected systems, the solar panels were connected together in series (called strings) to create higher voltage DC, which is good for reducing losses. However, this also created some problems.

That’s why the Micro-inverter was invented.

Micro Inverters

A micro-Inverter is simply a miniaturised inverter, sized to suit individual solar panels rather than a string of solar modules.

They aren’t new; they first appeared in the late 1990’s but arguably it was a bit too early and the technology suffered from reliability issues and high prices. In the last few years, though, they have re-surfaced and are starting to really take off.

Around the world there are at least 21 different brands of micro inverters, but in Australia, the most common brand by far (and the only one I’d use) is Enphase.

Here’s what one of the little fellas looks like next to its conventional alternative, a big, bad string inverter.

string inverter vs microinverter

AC Solar Panels

An AC solar panel is simply a solar panel that has been fitted with a micro inverter so that it produces Alternating Current instead of Direct Current.

A typical “Series String” array

Most of the solar panels installed in Australia right now are configured like this, with one big inverter and one big DC voltage. If that 600V DC arcs then there’s going to be a bang! And possibly a fire (which is why you should never skimp on installation cost).


An array of solar panels with a central inverter

 A typical “AC Solar Panel or Micro Inverter” array

An array of solar panels with a micro inverter

What’s good about AC Panels and micro inverters?

There are many complexities caused by the traditional way of connecting solar panels (in a series string), which Micro Inverters can help overcome, including:

High Voltage DC

High Voltage DC produced by a series string solar power system can create a risk of very high-temperature arcing and potentially fire. Because microinverters convert to 240V AC, the potential for this to occur is greatly minimised.


High-voltage DC requires relatively expensive protective switches and fuses. By using AC, switchgear is more commonly available and thus cheaper.


Because microinverters optimise each panel separately, they handle individually shaded panels well and, for many years, were the obvious choice for solar arrays that had encroaching shade.

But – what has been the conventional thinking over the years may need to be revisited as string inverter technology has evolved. In a 2021 field test that pitted a Fronius Gen 24 string inverter against Enphase microinverters, there was very little difference in how both handled varying degrees of shade across a single panel.

Whether this finding will apply across the board remains to be seen, but a report on a study of 200 solar systems in France published in late 2021 concluded there was no performance advantage to microinverters over string inverters generally.

Monitoring and fault finding

Almost all inverters have some level of monitoring and fault finding however, it can only see the combined output from every solar panel in the series string. A micro inverter however, can monitor each solar panel individually, allowing you to identify exactly what’s happening more quickly and easily. 

Factory fitted

Assembling and connecting components in a factory environment is inevitably a more controlled environment and can potentially save time and money. Some solar panel manufacturers now factory assemble micro inverters to produce AC Panels.


If your series string inverter develops a fault, your entire solar array stops producing power until it is fixed. If a micro inverter develops a fault, the remaining units can continue to operate, so you should have a more reliable system.


Series string inverters can only accept a specific number of solar panels per inverter, so it’s not always possible to add a few more panels later. AC Solar Panels, however, can be added much more easily because they are independent of each other – though adding a handful of panels to an existing array won’t be cheap.


In a series string, all your solar panels need to be connected in the same orientation so they are combined to produce the right voltage at the same time to fire up the inverter. Because they operate independently, AC solar panels can be oriented in any direction and will not affect the operation of other solar panels. 

What’s bad about AC panels and micro inverters?

Nothing is perfect, and micro inverters do have some downsides:

They’re on the roof

If your micro inverter develops a fault, someone has to get up on the roof and disconnect it from under your solar panel. This can add time and cost compared to simply taking a series string inverter off the wall.

Weather effects

Because micro-inverters are on the roof (albeit under the solar panels), they suffer from more weather extremes including heat, cold and moisture. This means they have to be carefully built and, in many cases, use electronic components that are more robust than would otherwise be required. As a general rule, temperature extremes reduce the efficiency of electronic devices and shorten their life.


Although they are getting close, micro inverters have not yet reached the same efficiency levels as series string inverters, so they can’t convert as much solar energy into electrical energy.


Again, they are getting close, but a microinverter system will add about 20-30% more to the cost of a solar power system compared to one using a conventional string inverter system.

When is an AC Solar Panel or Micro Inverter a better choice?

As you can see, there are several advantages to AC solar panels using micro-inverters. The most common reason people choose them is that they have shading or they need to install panels on more than 2 or 3 different roof directions.

An increasing number of people also choose micro inverters because they are prepared to pay a premium to monitor individual panels, increase their redundancy and allow for future expansion. The other benefits described tend to strengthen the case; some people love having the latest/newest technology.

Micro inverters are a good choice if you have severe shading or sub-optimal orientation.

Beyond this, micro inverters become a personal choice about how much you want to pay, balanced against their advantages.

Who sells AC solar panels and micro inverters?

We know of 19 Micro Inverter manufacturers around the world including: Apparent, Delta, Sparq, Kaco, ABB, Array Converter, GreenRay Solar, Hoymiles, Azuray Technologies, Petra Solar, Direct Grid, Accurate Solar, OKE/SMA, Exeltech, National Semiconductor, Larankelo, Enphase, APS, SWEA & Plug & Power.

But the only ones I’ve ever seen in Australia are Enphase and APS. Enphase is undoubtedly the market leader (and the only ones I’d put on my own house).

There is a growing list of big name PV companies around the world who have partnered with micro inverter companies to produce and sell AC solar panels, including Trina Solar, BenQ, LG, Canadian Solar, Suntech, SunPower, NESL, Hanwha SolarOne, Sharp and probably more that we haven’t heard of yet.

A growing number of distributors and dealers can access micro inverters and fit them to pretty much any solar panel you like.

The last word

A few readers have asked if AC inverters represent a “Do-It-Yourself” option, and the short answer is no, although it is tantalisingly close. Because you are dealing with 240V AC power, a licenced electrician is still required to connect them, and for rebates or FITs you’ll need an accredited installer.

Just how much of the market micro inverter-equipped AC solar panels take remains to be seen, but one thing is for sure; they do solve some hairy problems and have a big future.

If they can get the cost down more, then they may well become the dominant solar inverter technology, with the big string inverters joining all those mainframe computers in the big electronic scrapyard in the sky.

More Resources:

Can you add batteries to a microinverter-based solar power system? The answer is here.

A (slightly) cheaper alternative to microinverters are DC Optimisers

And finally, you can get 3 quotes for microinverter-based solar power systems here.


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