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PV system showing its age
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RenewableCandy



Joined: 12 Sep 2007
Posts: 12469
Location: York

PostPosted: Mon Jun 23, 2014 11:24 am    Post subject: PV system showing its age Reply with quote

LIke "all things electronic" (at least, in my experience) an inverter will eventually get upset and pack up. Ours did so, with perfect timing, 2 days before midsummer Sad

But enough whingeing. The techie chap I spoke with, after taking us through a complete powerdown and powerup to check that it really was, to use the technical term, fecked, explained that these are the type of thing that needs checked-over every few years. Especially if one happened to have had a system put in during the heady early days of FiTs.

The question is, to those others who have a bog-standard grid tie system: has anyone had theirs checked-over, do any faults get found, and how much does one generally pay for the privilege? Does anyone have a "service agreement" (like the ones some people have for boilers)?
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Potemkin Villager



Joined: 14 Mar 2006
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Location: Narnia

PostPosted: Mon Jun 23, 2014 7:54 pm    Post subject: Reply with quote

It would be interesting to find out what failed and why. It could be something simple that is easily and cheaply repaired and then again probably not! I imagine the replacement cost hurts.

Roof mounted PV panels and wiring are potentially good antenna systems for intercepting atmospheric disturbances like nearby lightning strikes and delivering nasty spikes to non indestructible inverter electronics.

The electricity distribution system is also a good source of all sorts of pulses, surges and transient over and under voltages of varying duration and amplitude.

Good design should provide some degree of protection but this can never be 100% effective. I really do not see how "checking it over" will help.

My guess would be that the power devices have been zapped, though it could be lots of other things.

I was very impressed once examining the lightning damage from a nearby strike done to the controller of a wee Prove turbine on a very exposed hill top location.

To use that technical term again it was welded and truly fecked! Sad
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Lurkalot



Joined: 08 Mar 2014
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PostPosted: Mon Jun 23, 2014 9:45 pm    Post subject: Reply with quote

A friend of mine has panels and they have stopped producing power , or at least that is what the control panel is telling him . However, he is having a problem getting anyone to actually look at them. One company wanted something like £350 to investigate the problem but by far the most common response was being told that " we can't touch that because it might invalidate your insurance" .
As can be understood he's far from happy about this especially after having a lot of trouble with the FIT payments. The FIT wasn't the most important element for him but when the panels were working he was producing more than he used on a regular basis.
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fuzzy



Joined: 29 Nov 2013
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Location: The Marches, UK

PostPosted: Tue Jun 24, 2014 5:18 pm    Post subject: Reply with quote

Could the company not deduct the £350 fee from any repair bill, that would seem reasonable. Does installation or maintenance require scaffolding?
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RenewableCandy



Joined: 12 Sep 2007
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PostPosted: Tue Jun 24, 2014 7:11 pm    Post subject: Reply with quote

I did actually have the presence of mind to check National Grid in case the voltage or frequency was very low or there'd been an upset, but there hadn't.

Meanwhile, the guys have got back to me with a date (next week) and a callout fee (rather a lot less than £350 thank heaven). The device had a 5 year warranty so with a bit of luck we'll be up-and-running by next Friday.

Pity we've not been contributing to what has turned out to be a record-breaking weekend for PV.
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biffvernon



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PostPosted: Tue Jun 24, 2014 7:54 pm    Post subject: Re: PV system showing its age Reply with quote

RenewableCandy wrote:

The question is, to those others who have a bog-standard grid tie system: has anyone had theirs checked-over, do any faults get found, and how much does one generally pay for the privilege? Does anyone have a "service agreement"


I think we got our system not long after you. How do you check over an inverter? I would guess that either it's working or it isn't. Mine is (so far). Or is there more to it than that?
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Little John



Joined: 08 Mar 2008
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PostPosted: Tue Jun 24, 2014 7:58 pm    Post subject: Re: PV system showing its age Reply with quote

biffvernon wrote:
RenewableCandy wrote:

The question is, to those others who have a bog-standard grid tie system: has anyone had theirs checked-over, do any faults get found, and how much does one generally pay for the privilege? Does anyone have a "service agreement"


I think we got our system not long after you. How do you check over an inverter? I would guess that either it's working or it isn't. Mine is (so far). Or is there more to it than that?
They are solid state and so, in the absence of some fancy measuring equipment, they are pretty much of a black-box item, I would think. We can be fairly confident, though, that they will have critical components in them that will have been deliberately designed to fail after a given amount of usage.

Having said all of that, I have found a link to some videos about how to repair inverters. Not something I'd tackle myself. Generally speaking, I don't like repairing things that don't move or where I can't clearly discern the physical relationships.

http://techluck.com/articles/2012/02/02/green/1328230633
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fuzzy



Joined: 29 Nov 2013
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Location: The Marches, UK

PostPosted: Tue Jun 24, 2014 9:14 pm    Post subject: Reply with quote

I couldn't recommend repairing an inverter. It's electrolytic capacitors, diodes and power transistors that will die. They will all have a hard life in any switch mode power supply. There are serious voltages and currents, and it's hard to troubleshoot if it won't run. It is also getting quite hard to trust critical electronic parts for amateur suppliers with many counterfeits.

It is just about possible to make an old time inverter. These were around before modern switch modes and use an oscillator to drive a centre tapped transformer. Much less efficient [probably 40% instead of 90+%] which limits their power output, but more overload tolerant and even repairable [to an electronics DIY] because they are fairly simple. Hell, back in the day, Maplin[!] even used to sell a DODGY..
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fuzzy



Joined: 29 Nov 2013
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PostPosted: Tue Jun 24, 2014 9:16 pm    Post subject: Reply with quote

Dodgy my arse..
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Lurkalot



Joined: 08 Mar 2014
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PostPosted: Tue Jun 24, 2014 9:25 pm    Post subject: Reply with quote

fuzzy wrote:
Could the company not deduct the £350 fee from any repair bill, that would seem reasonable. Does installation or maintenance require scaffolding?


To be honest I don't know about the money aspect , my friend dismissed that quote almost immediately without really getting any more details. He can be short tempered and decides things quickly sometimes without properly thinking things over. I haven't seen him for a couple of weeks as our work patterns are different. Installation would indeed need scaffolding although presumably an initial inspection wouldn't I assume.
My friend and I live in Staffordshire so probably RC's guys wouldn't be able to help unless it's a national company
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Little John



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PostPosted: Tue Jun 24, 2014 10:42 pm    Post subject: Reply with quote

fuzzy wrote:
....It is just about possible to make an old time inverter.,,,.


One of the funniest things I have seen on the internet is a home-made mechanical investor someone made. Basically, it consisted of a shaft being turned that had brushes on it that, as the shaft rotated, switched the current back and forth. It was used to power a small AC device. Presumably, once the current has been converted to AC, a transformer could then be used to take it to whatever voltage was required. I would think such stepwise mechanical inverters would kill any delicate modern electronic device, though.

edit to add:

found it..Smile

https://www.youtube.com/watch?v=k46Z8Pg0I4g
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Tarrel



Joined: 29 Nov 2011
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PostPosted: Wed Jun 25, 2014 12:12 am    Post subject: Reply with quote

"Mechanical Investor"?? No wonder the stock markets keep climbing! Very Happy
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adam2
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PostPosted: Wed Jun 25, 2014 7:33 am    Post subject: Reply with quote

A modern solid state inverter, either grid tied or stand alone, either works or does not work IME. I doubt that much is gained by routine servicing.

In case of failure, replacement is the only realistic option in most cases. Repair might be viable but is most unlikely to be a DIY project unless one has considerable experience of modern power electronics and a well equiped workshop.

It is well to ensure by frequent observation that a grid tied inverter is indeed producing about the expected output. A failure that goes undetected for months could result in significant financial loss.

If a large installation contains several identical grid tie inverters, it might be worth keeping a spare on site. Unlikely to be worth while for a smaller installation.

If a stand alone inverter supplies anything important then it is sensible to have a spare. If life depends on electricity, then the entire installation should be duplicated, AND a spare inverter stocked.

Routine servicing of components OTHER than the inverter might be prudent, but since this consists largely of a visual inspection, many people could do this themselves.
Inspect modules for cleanliness, security of fixings, and any damage. Ensure that modules have not become shaded by tree growth etc.
Check cables for damage.
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fuzzy



Joined: 29 Nov 2013
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PostPosted: Wed Jun 25, 2014 2:40 pm    Post subject: Reply with quote

stevecook172001 wrote:
fuzzy wrote:
....It is just about possible to make an old time inverter.,,,.


One of the funniest things I have seen on the internet is a home-made mechanical investor someone made. Basically, it consisted of a shaft being turned that had brushes on it that, as the shaft rotated, switched the current back and forth. It was used to power a small AC device. Presumably, once the current has been converted to AC, a transformer could then be used to take it to whatever voltage was required. I would think such stepwise mechanical inverters would kill any delicate modern electronic device, though.

edit to add:

found it..Smile

https://www.youtube.com/watch?v=k46Z8Pg0I4g


rotary convertors were found in all sizes to convert single to 3 phase or for frequency changing back in the day:

http://ddunlop.com/2009/10/irt-substation-13-rotary-converter/

But after that came the transformer based DC to AC inverter, much heavier than a modern switch mode, but good old tech

I think airplanes still use 400Hz supply so that transformers can be smaller
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RenewableCandy



Joined: 12 Sep 2007
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PostPosted: Tue Jul 01, 2014 11:38 pm    Post subject: Reply with quote

Update: techie chap arrived bright and early on Monday morning. It turned out that the Inverter was perfectly correct in telling us there was no mains supply to it: one of the connections (round the back of the attic wall where I couldn't see) had dropped off! It looks as if the whole escapade hasn't even cost us anything (other than about 30 quidsworth of lost FiTs). Phew!

However it offers all-and-sundry a chance to learn one thing: check, fill-in, return, and keep a copy of, any guarantee-type paperwork for anything big like a PV Smile You never know when it might come in useful!
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