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ABB Power-One Aurora Solar Inverter

Unfortunately, this seems to be what happens to all ABB / Power One inverters shortly after the guarantee elapses. Once they fail, ABB will do absolutely nothing at all to help their customers.

We have a solar electric power system on our roof. It generates more electricity than we use together in our home and our business combined, which helps us to try to reduce our carbon footprint. For six years the inverter worked perfectly, waking up with the sun and spinning out electricity meter backwards. Unfortunately, in July 2018, after six years, the ABB Power-One Aurora inverter failed with an error code "Error! Int.Error   E031"

I contacted ABB immediately through a webform, enquiring about whether the invertor could be repaired, costs of repair etc. and received the following remarkably short and unhelpful email in return:

 Goedemorgen Emmanuel,

 De garantie van uw inverter is verlopen op 17-08-2017.
 Helaas kunnen wij geen interventie uitvoeren.

 Mvg.

 Xavier
 ABB

i.e. the guarantee ended on the 17th of August 2017 and ABB will do absolutely nothing whatsoever to help their customers once the guarantee has expired. They did not offer to repair the inverter, they didn't provide any information about having it repaired elsewhere, they ignored my request for a service manual and circuit diagram and they didn't even to try to sell me a replacement. What's more, my name is David, not Emmanuel. i.e. they didn't even bother to change the name in the reply to another customer which they copied and pasted to me.

ABB's customer service made me decide that the last thing I'd do was buy a replacement inverter from ABB, leaving me with two options: repair or replace with another brand

A new inverter or try to repair ?

A new inverter costs around €1000. It's a considerable sum and adds a couple of years to the time which it will take for the solar panels to pay for themselves. What's more, the inverter still starts up and makes hopeful noises (relay clicks) and displays information on the display so it's clearly not completely dead. Rather, it's almost certainly the case that just a small and inexpensive part has failed.Throwing out the whole inverter and buying a new one is exactly the opposite of what should happen with devices like this. We bought it to reduce our impact on the planet, not as a throw-away item to be replaced after just a few years.

So before laying out the expense (both financially and environmentally) of replacing the inverter I decided to try to fix it. First stop was searching the internet for people who had the same problem. It turned out that a lot of people said the fault was "a failed relay". When I took the inverter apart I found this:

Obvious discolouration on and around a relay in the centre of the board

Close up you can see that it's been quite hot

The opposite side of the board is burnt around one pin of the relay

There's actually a little crater around where one of the pins of the relay used to be

I then found an online video in Italian in which someone fixes an identical inverter simply by resoldering one of the pins on this relay. The damage to my inverter is worse than his: I have no pin left to resolder. However I decided that this could still be fixed.

Solving the E031 error code problem

The relay in the centre of the PCB had obviously failed and various people online as well as a reply from the company which installed our setup suggested that the E031 error code means relay failure. The relay is Zettler model AZ2150W-1AE-12DEFT, a twelve volt coil relay rated for high current and voltage switching. It's small but the manufacturer's data suggests that it can switch 277 V AC at 30 A. The relay has a standard pinout so could be replaced by similar products from another manufacturer but I ordered the exact same model type online as this was the simplest way of ensuring that a compatible part would be received.

My replacement relay. Exactly the same model as before, but with a slightly increased specification for voltage switching.

In order to fit the new relay it was first necessary to remove the old one. This was quite difficult because the copper pads on the PCB are large and have vias which conduct heat away to the other side of the PCB. I found that none of my existing soldering irons was up to the job so I bought a more powerful soldering station which when set to 400 C made short work of the existing solder. This also made it easy to solder in the new part in its place, which also requires the abililty to heat up the large copper pads.

Before - a crater in the PCB

After - It looks OK from a distance, though less pretty in this closeup. A piece of copper wire soldered to the PCB provides a mechanical joint and a good path for current and for heat and the whole repair is covered in solder which makes a good contact with the relay pin.

In order to make up for the crater in the PCB around one pin of the relay I first scraped away the solder resist and burnt on carbon on the PCB around the hole, then soldered a piece of thick copper wire to the PCB so that it ran past the relay pin. A bit more solder connected the pin to the wire and covered the entirety of the pin. A close-up photo doesn't look very pretty but overall there should now be a good path for both current and heat.

New relay vs. old. You can still see a very small part of the mostly missing pin on the old relay.

From the top side, the PCB now looks good. There's still a bit of discolouration of the PCB from the heat generated before, but the relay is fitted perfectly.

Just four solder joints need to be made. The total repair time was about 30 minutes, an hour if I'm very generous, including taking the inverter off the wall and removing all the bolts which hold it together, making the repair and putting everything back together and returning it to service in the loft.

Success ! The inverter works again

And the result is... that the inverter works correctly again. Instead of spending €1000 on a new inverter and sending the old one to be recycled imperfectly or dumped in a hole in the ground, the existing inverter has been given a new life by replacing the one €5 component which had failed. This not only saves money but also reduces our impact on the planet. It also reduces the pay back period of the solar generating system overall making the entire project more reasonable. There's a huge amount of embedded energy in a device so large as the inverter. We have saved this energy by replacing just a relay.

The next morning: The repair has worked and the inverter woke up today with the sun just as it used to. Between yesterday afternoon and this morning it's so far generated electricity worth about €1. This is a large proportion of the €5 cost of the new relay, but would be a very small proportion of the €1000 cost of a new inverter.

A second failure and a second repair

For more than eighteen months, the inverter worked perfectly normally after the repair detailed above. However on the 11th of February 2020 it again failed with the same E031 error message. I didn't notice this until the morning of the 12th. At least this time I knew what the problem was likely to be, and it turned out to be a very easy repair with no new parts required.

The previous repair remains good and this time a different relay has stopped working.

Underneath the circuit board the damage is around the same pin of the relay as the previous time, but in this case it's much less extreme than last time and there is no apparent damage to the relay itself.

This time all I needed to fix the problem was solder. First of all I had to clean up the sooty mess, of course, so that a decent solder joint was possible.

The repair was easier this time because I didn't need to fit a new relay. The problem was merely a melted solder joint and this was made good in a couple of minutes by simply re-soldering that joint. In the previous example the damage was more extensive, leaving the PCB with a crater which I had to repair. Perhaps the failure was less extreme this time because it occured during winter when there was less current flowing so less heat caused by the breakdown of the solder joint. As a precaution I also re-flowed the solder around the other relays which have not yet failed.

One piece of good news: new inverters seem to cost a little less than last time that I checked. It appears to be possible to buy a Chinese model with a ten year guarantee (i.e. twice as long as our now eight year old twice failed ABB/Power One) for about €750. Perhaps the next time this thing fails I'll consider buying one of those...

Planned obsolescence

I was shocked by ABB's complete lack of interest in making our existing inverter work for longer. I wouldn't necessarily expect them to offer a repair as I have done above but they could have offered at least to swap the faulty PCB or have suggested a company which could make a repair. While I was inside the product I also found that they had also painted over all of the integrated circuits to prevent identification and easy repair. Not impressive at all. Such dedication to planned obsolescence is something you'd not reasonably expect from a company producing a "green" product.

Another reason not to buy from ABB. They paint over the identifying text on top of the integrated circuits inside the inverter in order to thwart attempts at repair.

If this inverter fails again and I can't fix it, I'll be looking for a replacement from a company which offers a longer manufacturer's guarantee and also offers to repair faulty inverters. These devices are not unrepairable, they just have been manufactured by a company which does not care.

At your own risk

Inverters are dangerous pieces of equipment. Not only is there 220 V AC within the inverter, but also the even more dangerous 220 V DC from the solar panels. While the AC power "lets go" 100 times a second, the DC power supply does not. As a result, if you are electrocuted by the electricity which comes directly from the solar panels this is far more likely to have a lethal outcome.

All that I have described above is what I did to repair my inverter. It's offered in the spirit of giving information away for free in the hope that it reduces the likelihood of repairable devices being scrapped.

I do not recommend that anyone attempt to replicate what I have done above as if it is an instruction manual. Several steps are missed out. If you don't know how to perform such a repair in safety then you should not attempt it yourself.

If your inverter has failed in the same way as mine had then it may be possible for you to find an experienced electronic engineer who can make use of the information above to repair your inverter. If this happens then I hope it works out for you, but I offer absolutely no guarantee of success or of safety.

If you copy what I did then you do so at your own risk.

Reactions

Before I decided to take a look at the inverter myself I contacted ABB through their web form and had no useful reply. After publishing this webpage I used twitter to contact ABB and this did bring a reply. In fact, several people from ABB phoned me in the next few days apologizing for the lacklustre response of their staff which they said fell beneath their usual standards. One of the people who phoned told me that if it was his inverter he would have made the same repair as I did. Another suggested that I should buy another inverter and said that there is a Dutch agent who would be able to supply a reconditioned inverter if I wanted to buy it. Everyone was polite and professional and I have no complaint about these calls, but they weren't offering anything I needed: I already had made a repair. Within about a week ABB stopped calling me.

In the months following the publishing of this webpage several other people with the same issue have got in touch. They've told me of similar lacklustre support from ABB (so I fear that the problem isn't solved at the company's end) and several people tell me that their inverters have now been repaired by either replacing the same relay or in some cases where there seemed to be a dry joint the repair was made just by re-soldering it.

Make a donation

Several people have asked me if they can make a donation as a way of saying thank-you for help with repairing their inverter. I very much appreciate this and you can make a donation of €5 by clicking on the button below:

Other ways to think us are simply to link to this page, which will help others to find this information should they be looking for it, or to link to our webshop.

I sell bicycle components for a living.