ABB is attempting a comeback to the residential solar market with the release of their new ABB UNO. The inverter manufacturer gained an unfavourable reputation in recent years with a problem they inherited – the Aurora. The new ABB, however, has been rebuilt from the ground up. In this post, I’ll first discuss the impressive history behind the engineering conglomerate called ABB. Next, I’ll look at the build of the ABB, pointing out what it has and what it hasn’t included. Following this, I’ll look into the operation of the ABB discussing temperature and heat, and its flexibility in solar design. Finally, I’ll give my view on what ABB is now infamous for – their warranty.


For this post, I went overboard to get the full story. I didn’t just test the ABB UNO 5kW in my office for a few months. It wasn’t enough just to meet with Joseph and Adrian from ABB Australia to fact check my blog. This time I also flew to Germany and shared lunch with a team of ABB engineers as we discussed the new UNO – as you do.


A little bit of history

ABB ‘s history goes back to two companies that both began in the late 1800’s. We’re talking around the time that Thomas Edison said: “We will make electricity so cheap that only the rich will burn candles.”

After about a century of trading, the two companies Allmänna Svenska Elektriska Aktiebolaget and Brown Boveri merged. In the 30 years since they have become one of the biggest conglomerates in the world. On 1st of May 2014, ABB completed their acquisition of a little solar company called Power-One. At the time, that “little company” manufactured what many considered the worlds best residential solar inverter. Power-One had named their baby the Aurora. When ABB took over, they ditched the Power-One and Aurora branding, and it became known just as the ABB PVI inverter.


That’s where it all went pear shaped. The glorious Aurora/ABB inverters started falling like flies – the EO31 fault being the main culprit. This is where I should be telling the heroic story of how ABB honoured their 130-year-old reputation and repaired or replaced every inverter within a miraculous 24 hours. It didn’t happen like that. I’ll tell that story at the end of this post. For now, let’s accentuate the positive.

As simple as ABB.

The Power-One Aurora seemed like a well-designed inverter, but it had internal components that let it down. What does a company with a 130-year history do to re-enter a rapidly developing market?

The clever people from ABB met (as history will embellish it) at a little sidewalk cafe over Campari and Gin, and penned the following on a napkin.

Rumor has it that at that French cafe the phrase was coined:

“A little bit from column A and a two bits from column B.”


Bring it on, ABB

So let’s have a look at what ABB have done. Is it really two parts Fronius with all the goodness of the Aurora?

The ABB UNO build

When I was a whipper snapper, my dad had a 1961 Ford Falcon. When I first “popped the bonnet” on the new ABB UNO, happy memories came flooding back of my days climbing in the engine bay of the Falcon to change the spark plugs.

The ABB UNO is built old school strong. That’s not surprising considering the engineering giant manufacturers the UNO in Italy. The “engine bay” is spacious, the heat sink is oversized, and the filters for the AC and DC are huge.

It’s got a screen!

Hallelujah! It seems inverter manufacturers are moving away from screens because of high failure rates, and forcing us to rely on wireless monitoring. However many inverters will not be connected to WiFi for their lifetime, and “directly connecting” to an app isn’t everyone’s forte, so a simple screen is a necessary backup.

Plug it in

ABB chose to keep with “plug in” connectors. They claim this makes the install quicker – I’m not sure about that – but it reduces the chance of water entering via damaged conduits or condensation entering through inadequate seals.

It’s Light

The 5kw inverter is 15kG. That’s heaps lighter than it’s 26kG predecessor and just lighter than new SMA 5kW (16kG).Weight matters when the installer is trying to hang it on the wall, and it’s good to know that inverters are being manufactured with fewer natural resources than before.

Load Control

While ABB UNO does not come standard with the ability to heat a hot water system with excess solar power, you can purchase an additional communications card for that purpose. This card is also required for export control. As we’ll discuss later, this feature is not fully ready.

DC Isolator

The version shipped to Australia at the moment does not have a DC isolator inbuilt. That’s because we have a stupid regulation about inbuilt DC isolators that will hopefully be overturned soon. If the standard does get changed, the UNO will be modified to include a DC isolator. This will reduce installation cost and increase reliability.

The “NO FAN” fallacy

I recently wrote an article on the new SMA inverter declaring it “fanless” because:

i) I couldn’t see it

ii) I was lead to believe this by SMA and,

ii) the spec sheet says it is cooled by “convection”, rather than by “fan”.

It turns out the term “convection” is ambiguous, I was misguided, and the SMA does have a fan. Just a teeny-weeny one.



 ABB Au Naturel

ABB state their inverter has “natural cooling”. I wondered what they mean by “natural cooling”. Does it mean:

A) “Don’t worry, we don’t use fans like Fronius, so we are super reliable”?  Or…
B) “No artificial colours or flavours were used in the Chinese manufacture of our cooling fans”?

I found a fan in the ABB. I can therefore only conclude the fan has no artificial colours or flavours.
My point is, the ABB has an internal fan – just in case, like me, you would presume otherwise.


The operation of the ABB

I didn’t do extensive testing of the ABB because its claims were not extraordinary. It’s just a robust inverter that inverters DC power.


The weighted efficiency of the ABB Uno is 97 %  which is 0.6% better than the Aurora and the Fronius Primo.
Baby steps in the right direction. With the price of panels today, inverter efficiency has become less of a talking point. However higher efficiency means less heat, and less heat means longevity.


I tested the temperature of both the ABB and the Fronius inverters when they were running at 2500W in an air-conditioned room using probe thermometers. Inverters had the lid on, and temperatures were taken over three days. I took the measurements at various locations, and the Fronius always ran cooler. These measurements were recorded at the top of the capacitors. In other locations, the variation was much larger.




This thermal image shows why the Fronius (left) runs cooler. It relies on three fans and a small heat sink to pump the heat out of the top of the small heat sink.

The ABB inverter (right) relies on natural cooling, which is referring to the huge heat sink on the back – and an internal fan with no artificial flavours or colours.





Design flexibility

ABB UNO Specification Datasheet

The input parameters on the 5kW UNO are similar to the good old Aurora. Let have a look at some of the key specs:

  • 5000W nominal
  • 5150 max
  • 3500W max per MPPT (the Aurora was 4kW)
  • 600V max open-circuit,
  • 90V min operational.


Say Whaaat?

5150W max? 3500W each MPPT?  Seriously? If you took the ABB spec at face value, you’d never buy one.
The good news is ABB was just joking. What the spec means is the maximum that each MPPT will convert is 3500W per phase or 5150W in total.

But if our job was inspected by the CER, they could fault us for being non-compliant with the specification!!

They could, but then you reply to the CER with an email from ABB like this:


In short, the ABB is an extremely design friendly inverter. If we needed to, we could put four panels facing north on MPPT1, ten panels east and ten panels west on MPPT2. (Some installers will say you can’t split east and west on 1 MPPT, but you can. I’ll cover that in another post soon.)


Online monitoring

Earlier this year I met for lunch with a team of ABB engineers at Intersolar in Germany to try to gain a better understanding of their upcoming product. I was thrown so much information about the online capabilities, and I left the meeting feeling extremely optimistic about their new product. This new platform would give us as the installer the ability to:

  • Monitor self-consumption and export power
  • Identify shading issues by scanning the inverters MPPT
  • Remotely adjust hot water relay parameters
  • Remotely adjust grid parameters
  • Allow for automatic microprocessor updates

This all sounds great. However, none of it is available yet. The ABB is still running on the old “Auroravision” platform which was great a few years ago when we were installing Aurora inverters, but the bar has been lifted. Most notably is the need for consumption monitoring and the ability to adjust the hot water relay parameters. I wasn’t given a clear indication of when the new monitoring platform would be released, but the vibe was “next year”. When it is fully released, It will become a serious competitor to the Fronius Primo.



Currently, the new ABB terms and conditions have not been released. That’s uncool. However, what we do know is it has a 10-year full warranty until the end of 2017. I’m looking forward to dissecting the new T’s & C’s.

It can’t be ignored that ABB’s warranty process in recent years has been pathetic. It’s not that they didn’t honour their warranty, but ABB’s supply of warranty replacements just did not keep up with the demand. To make it worse, it felt like communication was poor during the warranty process. To be fair, how many times can ABB Australia call to say “we still don’t have your replacement inverter”. The warranty process left the solar industry jaded with ABB – many installers will never trust ABB again.

It would be easy to point the finger and say that ABB should have been more like Fronius when they suffered through their IG15 disaster. However, the number of Fronius IG15’s installed in the Solar industry’s infancy would be dwarfed by the number of Aurora inverters installed at the height of the solar industry.

I’d be inclined to see the positive. Although there were long delays, ABB generally honoured their warranty. They hopefully learned from their mistakes and spent years designing what will most likely be a reliable inverter. However, they will need to pull a rabbit out of a hat to convince other installers. A good start would be a guaranteed inverter replacement time with compensation carrot if the timeframe is not met. Even better if they stated that clearly on the yet to be released terms and conditions.



The new ABB inverter looks strong. It’s got a screen, plug in connectors, it’s light, and it has the option for hot water load control. Unfortunately, it doesn’t have a DC isolator, but that may change. It’s massive heat sink does a good job at “natural cooling”, but don’t be fooled by the term, because it still has an internal fan. The ABB UNO is super flexible with its design parameters, however, the updated online monitoring is yet to be released. Once the online portal is fully implemented, it will be a serious contender to Fronius. While many are jaded with ABB because of their warranty experience, I think ABB has the ability to pull off a ‘Lazarus” and get it right this time. It may just need a rabbit and a hat, or a carrot.


3 Comments on The new ABB uno inverter review (2017)

Ian G said : Guest Report 2 weeks ago

Thanks for the review of the new ABB inverter. I'm on my third "Aurora" style inverter in 5 years. They seem to get the dreaded E031 fault like clockwork after 2 years. In my experience the ABB warranty service has been good. The first replacement came in a few days, while the second took a bit over a week. The worst part is that if (or more likely when) this one fails it will be out of the 5-year manufacturer's warranty period and the installer is no longer in business (no prizes for guessing who!) This one is a bit different to the others, so perhaps there was an interim fix - let's face it, they had to have worked out where the weakness was with all that experience.

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Mark C said : administrator Report 2 weeks ago

Thank's Steve! A quote left out of my post was from a large electrical wholesaler. A while ago I said to him "I'm surprised such a huge company like ABB have been so bad with their inverter warranty procedure. His reply with long experience in ABB product warranty (switchgear etc) was telling ... "I'm not".

Steve bourke said : Guest Report 2 weeks ago

I am an electrical engineer in the industrial area. I would not touch abb products with a 40ft barge pole. Crappy products made in china and high cost and incompetent unreliable after sales service. This opinion is based on 25 years across all abb products from lv and hv switchgear and instruments. Stay clear and tell your customers to be very wary.

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