Solar PV repair quote.

[Blockhead]

Hello.

I'm a newbie on here so hope I'm posting in the correct place and hope someone may be able to offer some advice!

About 3 years ago I had an extension built and had to move two PV panels to accommodate the new roof joining the existing one. I have 16 panels (thin film, installed in 2014) in 4 strings (I think!, there's 8 cables down to 2). I moved the two panels and joined them into the other panels. The array has, in my opinion, worked fine since. Then a couple of weeks ago I noticed the array was not producing any power on the inverter (SMA sunny boy SB2000 HF30).

I asked a local electrician / solar installer to troubleshoot my problem. 

He tested the array from the last two T joints, so assuming 2 strings at a time, and identified an imbalance of voltage between the two. He asked if there had been any modifications and I told him I had altered the panels a few years previous but it had been ok until a couple of weeks ago. There followed a lot of tutting and headshaking and telling me I shouldn't have touched them and lucky I didn't burn the house down!!

Fair play...I've got broad shoulders, I can take a telling off (which I did).

His theory is, because there is an imbalance due to my intervention in 2018, that that has probably damaged the inverter. He has quoted me £900 plus vat to put scaffolding up to take the panels off, check for damaged / burnt connectors, re-connect them correctly and if the inverter is damaged another £650 plus vat. I have no problem with the chap, came recommended and has good customer reviews, so no doubt about his credentials. Not sure if its worth doing, just under 2k will take me up to 5 years to get my money back by FiT. 

Does each string have to be the same voltage as the other strings?

Can the inverter sense an imbalance when the voltage comes down to 2 cables, surely there is only one voltage when it gets to the inverter?

Could it just be the inverter has packed up? 

Would appreciate any advice/opinions on this....thanks.

 

[SPECIAL LOCATION]

Hello.

I'm a newbie on here so hope I'm posting in the correct place and hope someone may be able to offer some advice!

(1) Welcome to the forum.

(2) Yes I would say your question is in the right place.

(3) I haven't got a clue about your problem, as me & Solar are about as probable as Boris Johnson speaking at a Labour Party Conference!!

(4) Have a few forum Beers/or Wine.. .  :Y Guinness   :Y Guinness :Y Guinness :Y Guinness :Y Guinness :Y Guinness

Then wait for Binky to return from his normal daily workload managing all of his customers who pay him money to keep the bills paid!

As Solar & Binky are joined together like the words of the old song..

"Love & Marriage or Horse & Carriage" 

Or..   like "fish & chips"...

They are just a 100% perfect match for each other!!

:Salute  

 

[Murdoch]

Unfortunately too many people with PV ignore the maintenance costs when doing the initial calculations - I was told to put aside some money each year to "save" for when the inverter needs replacing.

I've got an APP on my phone for mine so can see what each string is producing etc which is very helpful.

Could your issues be pigeon related ? This is quite common

Fingers crossed @binky will be along soon 

BTW I think the £900 is very reasonable for scaffolding etc ....

 

[binky]

Seems I have a fan club  :^O

OK, imbalancing strings does affect peformance, your inverter will be trying to find the maximum power point from a predesignated input curve, but effectively it has 2 curves to try and track. It will work like this but you lose some performance.

Prices quotes for the works seems quite reasonable, but I suspect your inverter has just died due to old age. The old SB HF series hasn't proved to be especially reliable - check it hasn't got an extended warranty on it. 

I've always been suspicious of T jointing DC strings - it's a practice I've always avoided. If you are going to the trouble of lifting panels, I would ask your contractor to consider re-arranging the panels into 2 strings. Your new inverter will almost certainly have 2 MPPT trackers, put half the array on each input. It might not be possible with the thin film panels to arrange the strings like that, I really can't remember the electrical characteristics of those panels as they dies out a long time ago, but I would be surprised if what I'm saying can't be done. Depending on where the T joint is, it maybe possible just to rearrange the cabling at that point and not lift the panels. I wouldn't be looking to lift panels unless testing showed a break in DC cable runs. 

 

[Andy™]

Seems I have a fan club  :^O

of course, you know much more about solar than many of us

 

[binky]

of course, you know much more about solar than many of us

 I think that's the nicest thing you've ever said to me  :^O

 

[Andy™]

 I think that's the nicest thing you've ever said to me  :^O

well i could have continued with 'but knows nothing about anything else electrical'

 

[Blockhead]

Thank you for your replies and the ideas.

Good to know that my moving the panels probably and hopefully hasn't completely ruined them over the 3 year period. 

So by moving a couple of them, I'm assuming I have unbalanced the strings and made them less efficient. Looks like I'm best off getting them sorted properly.

Thanks again.

 

[ProDave]

This highlights a problem with solar PV on a roof.  To do anything with them needs scaffold which is not cheap and is probably a large part of the cost.

My own are ground mounted at this house (shading from tress was the reason for that) and at the previous house they were on the garage roof which at a push you can access just with a pair of ladders or a small scaffold tower which you could DIY erect for a lot less than full on scaffold.

 

[binky]

This highlights a problem with solar PV on a roof.  To do anything with them needs scaffold which is not cheap and is probably a large part of the cost.

My own are ground mounted at this house (shading from tress was the reason for that) and at the previous house they were on the garage roof which at a push you can access just with a pair of ladders or a small scaffold tower which you could DIY erect for a lot less than full on scaffold.

It's only an issue if something goes wrong, or someone put panels on a knackered roof. Other thatn that they should be fine for 30 years or so. I've only come across 3 fialed panels, 1 was directly under an aerial and the birds shat all over that panel eventually cuasing a hot spot and burn out, the other 2 were donw to a prat with a pressure washer cleaning the roof and damaging the anels in the process. The most failure is water ingress into a connector, cable tying the connecotrs to the rails stops that, along with actually doing the connectors up properly in the first place with MC$ spanner which costs a couple of quid. Pidgeons can be an issue nesting under the panels, the build up of debris can cause earth leakage via the backsheets of the panels. The backsheets are slightly permeable soft plastic sheet, bits of stick sticking in it doesn't do it a lot of good. 

 

[Blockhead]

Very interesting!.......there's so much more to it than you think!

We do have a lot of pigeons in this area and my neighbour was only saying the other day that they sit on the edge of my roof and do their business on her pathway!

I'll highlight the fact to the contractor....

 

[Geoff1946]

Pidgeons can be an issue nesting under the panels, the build up of debris can cause earth leakage via the backsheets of the panels. The backsheets are slightly permeable soft plastic sheet, bits of stick sticking in it doesn't do it a lot of good. 

Glad you mentioned that. My installation is on a bungalow roof in a relatively rural place and I've often thought the space behind looked ideal bird nesting territory. It hasn't happened yet, over seven years, but I will continue to keep an eye out each spring. Any visitors will be quickly given their marching orders before they can get established..

 

[Geoff1946]

they sit on the edge of my roof and do their business on her pathway!

That must be quite difficult to do. Perhaps she's done something to upset them.

 

[Blockhead]

LOL.....the pigeons sit on her roof as well, but apparently only poo from mine

 

[Murdoch]

Very interesting!.......there's so much more to it than you think!

We do have a lot of pigeons in this area and my neighbour was only saying the other day that they sit on the edge of my roof and do their business on her pathway!

I'll highlight the fact to the contractor....

If you don't have mesh installed around the perimeter of you panels I would say NOW is the time to add them when the scaffolding is up

We have mesh around ours but I left a slightly larger gaps between the top and bottom rows and the ruddy pigeons can drop in between them ........ and like doing that. So I am in the the process of trying things to get the gap filled up! Fingers crossed it won't mean scaffolding.

 

[Blockhead]

That's a good idea Murdoch.....I'll look into that!

Noticed someone down the road had it fitted last year and For the life of me I couldn't think why.....until now!

 

[Bruspark]

to troubleshoot my problem. 

He tested the array from the last two T joints, so assuming 2 strings at a time, and identified an imbalance of voltage ...

His theory is, because there is an imbalance due to my intervention in 2018, that that has probably damaged the inverter. He has quoted me £900 plus vat to put scaffolding up to take the panels off, check for damaged / burnt connectors, re-connect them correctly and if the inverter is damaged another £650 plus vat. I have no problem with the chap, came recommended and has good customer reviews, so no doubt about his credentials. Not sure if its worth doing, just under 2k will take me up to 5 years to get my money back by FiT. 

So if there is an imbalance of voltage but still within a credible range   the inverter should not have failed and should  be able to produce at least some power. 

You may have made the array sub-optimal (TBH the UK weather is sub optimal too) but if there's voltage into the inverter I'd far rather the guy tried a different inverter at ground level before going £££ ape on scaffolding - perhaps to no avail.

 

[Geoff1946]

Just out of interest, although I may have a serious interest at some time in he future, are there no independent repair services for invertors? 

It can't be that hard, if you could access circuit schematics. The majority of failures are likely to be overloaded and overheated semiconductors, or dried up capacitors.

My own unit failed at about three years old but it was just a burned out DC connector, probably due to duff crimping. The installing company, (and their 5 year guarantee),  had left the business, so I just replaced the connectors, but who knows what the future may hold?

It seems to me quite wrong that a £xxx piece of electronics is scrapped for the want of a few £x components.

 

[binky]

Just out of interest, although I may have a serious interest at some time in he future, are there no independent repair services for invertors? 

It can't be that hard, if you could access circuit schematics. The majority of failures are likely to be overloaded and overheated semiconductors, or dried up capacitors.

My own unit failed at about three years old but it was just a burned out DC connector, probably due to duff crimping. The installing company, (and their 5 year guarantee),  had left the business, so I just replaced the connectors, but who knows what the future may hold?

It seems to me quite wrong that a £xxx piece of electronics is scrapped for the want of a few £x components.

 In short, no, apart from one inverter manufacturer, Samil,  that has gone completely. A fella that used to work them repairs their gear. 

I suspect most of the failures are simple components, a favourite for cheap inverters is the AC relay. SMA offer a service swap for their stuff, ie they will send you a repaired unit under warranty should there be any issues, so it's not like inverters can't be repaired, but if there's a design fault that causes a failure in the frst place, then swopping like for like components is not such a good idea. Biggest issue I can see is a/ software, b/ new inverters can be bought relatively cheaply and are more efficient than old units, so there's limited scope for the cost of repairing a unit. 

 

[roys]

 In short, no, apart from one inverter manufacturer, Samil,  that has gone completely. A fella that used to work them repairs their gear. 

I suspect most of the failures are simple components, a favourite for cheap inverters is the AC relay. SMA offer a service swap for their stuff, ie they will send you a repaired unit under warranty should there be any issues, so it's not like inverters can't be repaired, but if there's a design fault that causes a failure in the frst place, then swopping like for like components is not such a good idea. Biggest issue I can see is a/ software, b/ new inverters can be bought relatively cheaply and are more efficient than old units, so there's limited scope for the cost of repairing a unit. 

When my SMA inverter failed last year, out of warranty, I phoned up SMA and they weren’t interested in part exchange, told me I needed to but a new one at £800 which I would get a 5 year warranty with. Needless to say I bought a Solis at £400 still with a 5 year warranty.

Gave my old SMA to ProDave to play with.