Solar Panel Inverters

[Nocton]

We have had our solar panels since August 2010.
Yesterday we received a letter re "a free health check and service of your system", saying that our inverter will have had a 5-year warranty which will have expired. The letter says: "Please contact our booking team free of charge to validate your warranty and book your Health check."
I am sure that the 'Health Check' will conclude that all is working well, that the warranty has expired and that we can have the warranty extended for a charge.
My question is: How likely is that the inverter will fail? I suppose that there is little real info on the life time of such inverters as no solar panels have not been installed for 25 years, so any warranty is purely speculation. And in any case, with 17 years to go until the end of our FIT contract, their is no guarantee that a firm giving a warranty will still be in business at the end, so we are reluctant to spend money on such a warranty. We have a monitor in the kitchen which is wirelessly connected to the inverter; we also record the quarterly FIT readings in a spreadsheet. There is no indication that the system's performance is in any way degrading.

[Meatyfool]

Au contraire.

The health check will conclude that the inverter has degraded from its initial efficiency of 95%+ to <pick a number out of thin air>% and so you are "just throwing FIT payments away".

But don't worry, lo and behold, we have an inverter on manager's special today, all you have to do is sign here ...

If you see your PV output reducing in your spreadsheet, then consider replacing. I'm sure you won't spot anything as there is annual/seasonal difference masking things.

Also, bear in mind if your inverter limits your output (ie max inverter output is 3300W but your panels could produce 3600W), if you install a "bigger" inverter you are in effect invalidating your FIT agreement as you can now receive FITs on more output.

Moral of the story: don't mend it if it ain't broken!

Meatyfool..

[supremetwo]

We have had our solar panels since August 2010.
Yesterday we received a letter re "a free health check and service of your system", saying that our inverter will have had a 5-year warranty which will have expired. The letter says: "Please contact our booking team free of charge to validate your warranty and book your Health check."
I am sure that the 'Health Check' will conclude that all is working well, that the warranty has expired and that we can have the warranty extended for a charge.
My question is: How likely is that the inverter will fail? I suppose that there is little real info on the life time of such inverters as no solar panels have not been installed for 25 years, so any warranty is purely speculation. And in any case, with 17 years to go until the end of our FIT contract, their is no guarantee that a firm giving a warranty will still be in business at the end, so we are reluctant to spend money on such a warranty. We have a monitor in the kitchen which is wirelessly connected to the inverter; we also record the quarterly FIT readings in a spreadsheet. There is no indication that the system's performance is in any way degrading.

Some companies are using the MCS database or lists from installers that have ceased trading.
Was the letter 'out of the blue' or from your own installer?

Once they get a foot in the door, they make dubious claims of short inverter lifetime plus exaggerated claims of increased output via inverter modifications.

Much discussion here:-
https://www.navitron.org.uk/forum/index ... 026.0.html
The guy came round - not technical just a pure salesman - looked at the set up, made lots of notes, asked for generation figures etc. He then ran then through an app on his phone, made lots of exaggerated assumptions and came up with a figure which said that if I upgraded I would be better off. He said my old inverter was not as efficient as the Solar Edge micro inverters (true) and that I could increase my system output by up to 15% (doubtful). He did leave all of the leaflets and a quote for about £5000.

They make the assumption that you will have to replace your inverter (at an inflated cost) and that the Solar Edge (or what ever brand of inverter they are using) is more efficient (it is) and therefore this will increase your generation (FiT payments) (also true). The final persuader is that after the upgrade it is guaranteed for the rest of the life of the FiTs. In my opinion it is not a total rip off, just a very expensive upgrade and some peace of mind if you need it. In some circumstances, like the poor installs with shading from a chimney or similar, then the payback may well be very good.

[supremetwo]

We have a monitor in the kitchen which is wirelessly connected to the inverter; we also record the quarterly FIT readings in a spreadsheet. There is no indication that the system's performance is in any way degrading.

My inverter connects to the computer and records all its parameters, which did detect a fault with one of the panel connectors resulting in the loss of half the output.

There is also a daily upload to pvoutput.org for comparison with other similar installations in the locality.
http://pvoutput.org/list.jsp?userid=6813

[Urbandreamer]

My question is: How likely is that the inverter will fail? I suppose that there is little real info on the life time of such inverters as no solar panels have not been installed for 25 years, so any warranty is purely speculation. And in any case, with 17 years to go until the end of our FIT contract, their is no guarantee that a firm giving a warranty will still be in business at the end, so we are reluctant to spend money on such a warranty. We have a monitor in the kitchen which is wirelessly connected to the inverter; we also record the quarterly FIT readings in a spreadsheet. There is no indication that the system's performance is in any way degrading.

The inverter WILL fail in the next 17 years. I am quite certian of the fact. The panels may be good for more than 25 years (with some degredation). The semiconductors and any coils in the inverter will have a symilarly long like. Electrolytic capacitors on the other hand usually die within 10 years. In themselves they are not a hugely expensive component, but you should expect to have to pay more than you would wish to replace them (if possible). In truth there will come a time when the ecconomic sense will be to simply replace the invertor.

http://www.solarmango.com/ask/2015/09/2 ... inverters/

Ps, I work with inverters to control the speed of electrical motors on expensive machine tools. Sadly the problem exists there too.

[Nocton]

Thanks for all the replies.
Re: "Was the letter 'out of the blue' or from your own installer?" It was out of the blue from a company I have never heard of (ESE Consultants, Liverpool based) and not at all local.
Re: "If you see your PV output reducing in your spreadsheet, then consider replacing. I'm sure you won't spot anything as there is annual/seasonal difference masking things." I think we would spot something after 7 years, which is enough to cover a wide range of solar fluctuations..

Taking all into consideration we shall wait to see what happens. Even if the inverter eventually does fail then a replacement or repair will be no more expensive than doing it now. As I mentioned, the system is working well.

[NeilW]

Ah, Is that what ESE are doing now the bottom has fallen out of the panel installation market.

I had them round for an installation quote when I was installing my panels to start with. All sales fur coat and no knickers

[supremetwo]

The inverter WILL fail in the next 17 years. I am quite certian of the fact. The panels may be good for more than 25 years (with some degredation). The semiconductors and any coils in the inverter will have a symilarly long like. Electrolytic capacitors on the other hand usually die within 10 years. In themselves they are not a hugely expensive component, but you should expect to have to pay more than you would wish to replace them (if possible). In truth there will come a time when the ecconomic sense will be to simply replace the invertor.

http://www.solarmango.com/ask/2015/09/2 ... inverters/

Ps, I work with inverters to control the speed of electrical motors on expensive machine tools. Sadly the problem exists there too.

And solar inverter manufacturers say 'superseded by a new model' and 'spares not available' and treat circuit diagrams and component lists of the old models as 'top secret'.

Does that happen with your commercial ones?

[Urbandreamer]

And solar inverter manufacturers say 'superseded by a new model' and 'spares not available' and treat circuit diagrams and component lists of the old models as 'top secret'.

Does that happen with your commercial ones?

Well yes and no. What happens is that after 10 years they go on a "spares only" list. Replacements now cost 2 to 3 times as much as a new model and 10 years later they will not be available. Manuals for the devices cease to be sold.

We are currently rolling out upgrade programs where every motor and invertor drive on the machines that we build are replaced on 10-20 year old machines. Machines over 20 years old need significant mechanical work as well costing a significant proportion of a new machine.

As regards invertor maintenence. Key things would be to check are that any fans are working. That the device remains "clean" and dry. That all terminals remain tight and to visually inspect the capacitor "cans". Electrolytics have a Y pressed into the top to allow them to swell safely as they start to fail. Heat, damp and dust (which holds moisture) are the key things that maintenece would address, but the costs of having someone do the insection could easily be counter productive. Cheaper to do as much as you regard safe* to do yourself, and to replace the invertor when it fails.

*Be warned, that could amount to only things that you can do with BOTH hands in your pockets. Inverters often have leathal voltages far above 240V and high currents. Turning off the mains may not even be enough to be safe, given the supply from the panels could be a high DC voltage.