Help with string inverter problem

PotentialEnergy

Hi everyone

I had a 3.99kW solar panel installed in Oct 2010 with an SMA brand inverter which was a Sunny Boy 3800 - in production for >5years by then. 5yrs8mths on, the readings per day seemed to halve. My installer sent an electrician who confirmed the voltage levels were OK and that it is the SMA Sunny Boy 3800 inverter that is faulty. SMA say it is out of their 5yr warranty and so I stand to fork out 500Euros+transport costs + VAT to repair and get a 'whopping':mad: 1yr extension to warranty. Thankyou for 'absolutely appalling customer care' is all I can say to SMA as when I rang to take the matter up on the basis of the Consumer Sales of Goods Act 1979, and it being under 6 years since I purchased the item, the chap scoffed/sneered at me.
Since then, I've found an academic paper that says string inverter reliability in 2006 was 5-10years whilst by 2011 it was 12years.

http:// engineering.case.edu/centers/sdle/sites/engineering.case.edu.centers.sdle/files/peshek.pdf

So, I've been very unlucky! Any thoughts on how to approach this with regards to recompense from SMA? How would the Small Claims Court look on my experience and their response? To my knowledge, I was never offered an extension beyond 5 years.

Going forward, my solar installer has provided quotes for a Samil 4400 inverter or a Solar Edge 3680 or 4000. What is the point of a Solar Edge 4000 over a 3680 i.e. What extra does it offer?

When it comes to reliability how do Samil(5yr guarantee) compare to Solar Edge(12 year guarantees)?

As I've got 19years left of FiT payments is it worth extending warranties to say 20years?

Samil 4400 is priced at £480+VAT with 5,10 and 15 year warranty extensions of 113,337 and 522 all with VAT to be added. So a new Samil with 20yrs warranty for £1202.40

SolarEdge 3680 £780+Vat with an 8 year warranty extension of 167+VAT. So a Solaredge 3680 for with 20yrs warranty for £1136.40

Solaredge 4000 is £810+VAT with same price for extension of warranty.So a Solaredge 4000 for with 20yrs warranty for £1172.40

So, in summary

1/ What comeback do I have against SMA? Supposedly a top brand German company!

2/ How does Samil compare with Solar Edge when it comes to reliability of their string inverters?

3/ What does a Solaredge 4000 offer above a 3680 for a standard FiT home installation of 3990W. The forum below goes into some detail but I'm still unclear.
http:// https://www.navitron.org.uk/forum/index.php?topic=19552.60

4/ Would you advise varying my warranty at all i.e. beyond 5 years for Samil or 12 for Solaredge

Thankyou for all guidance/views given. :beer:

I quizzed my installer on the 3680v4000 business and he's simply responded saying he's go for the Samil with just a 5 year guarantee? Is he just ducking out of answering because the Solaredge 4000 offers me no benefit over the 3680? I appreciate only £36 is at stake but I still want to know if it is £36 worth spending.

Ectophile

If you didn't buy the inverter direct from SMA, then you have no contract with them and so no grounds to take them to court.

Any legal action would have to be against the supplier. It would be up to you to persuade the court that an inverter should last more than 5 years. Even if the court finds in your favour, then you would still not be entitled to the cost of a brand new one, as you had 5 years' use out of the old one.

Martyn1981

PotentialEnergy wrote: »

Hi everyone

I quizzed my installer on the 3680v4000 business and he's simply responded saying he's go for the Samil with just a 5 year guarantee? Is he just ducking out of answering because the Solaredge 4000 offers me no benefit over the 3680? I appreciate only £36 is at stake but I still want to know if it is £36 worth spending.

Hiya.

Sorry to hear of the inverter failure. I appreciate you are a bit peeved at it not lasting longer, but even if life expectancies are (on average) much longer than expected, somebody has to be at the poor end unfortunately.

I'm slightly confused by you mentioning SolarEdge (SE) inverters. I have one, and they are excellent, but the inverter itself is 'dumb' the clever bit is done by PO's (power optimisers) which you need attached to each panel. This set up maximising the individual potential of each panel, and minimising the effect of shade.

If you don't have PO's, then I'm not sure why you'd use a SE inverter.

I've heard good things about the Samil's, but that's just hearsay, however they are cheap and efficient. Apparently their shade management software isn't as good as SMA's, which may account for some of the extra expense of SMA kit. But if you don't have any significant shading then that's not a concern.

I'm following a lead here, not trying to persuade you, but if you are still looking towards the Samil, then it seems to me that the 10yr cost, is the best, since you extend the warranty by 100% for 24% cost outlay. It's half the 20yr cost, so why pay more more up front, just see how it goes. If it lasted 12 yrs, then you'd already be within the 20yr warranty for no extra money. If it lasts 20yrs, then you're laughing.

Size wise, anything that can output 3,600W A/C (or so) will do. Bigger might get less capping at peak times, but a 10% undersized inverter should make up for it with slightly higher efficiency at low generation levels.

Keep chatting, better to make sure this all makes sense than to go off confused and make a rash decision.

Mart.

PS. My SE inverter still has 8yrs left on the warranty, but my two SMA's will be 5yrs old in a couple of weeks. Ho hum!

PotentialEnergy

Hi Martyn
Thankyou for questioning the selection of Solar Edge Inverter. I'd assumed it could be used as a like-for-like replacement of the string inverter so the 12year warranty had appeals. As you say though, if all the smart tech stuff is done in the microinverters on the panels it is pretty dumb. But, what extra is a standard string inverter - dare I suggest SMA - offering? Equally, with a 20year warranty the SE is cheaper than Samil's

You may want to contact SMA or your installer about an extension of the warranty on the SMA. I was never given the option. Obviously your choice.

Plenty of people wax lyrical about SMA in terms of reliability. One installer who provided feedback to someone else a couple of years ago spoke of SMA's average reliability being 19years. Ha ha ha ha is all I can say. I appreciate as you say that average means there will be winners and losers. But I feel I've been an unreasonable loser. It is housed in a garage that is largely sheltered from direct sunlight so nothing like the extreme warmth of a loft.

I'm trying to find an analysis of string inverters available in the UK giving me a chance to see how Samil compares with its peers. One website I found referred to Huawei being topnotch but what brand names does it use and there again, does it do 3.6kW 1ph inverters?

Thanks again.

gefnew

Hi
there was always an option to upgrade your inverter warranty
if you would have done some research.
sma have some options to extend your original warranty up to 20 years within the first five years of ownership with two variants of execution. self replacement, or comfort replacement where it is installed by approved technician.
by the way Martin check out sma website if your inverters are nearly out of warranty and look at the prices

PotentialEnergy

Hindsight is such a wonderful thing. But thankyou for making me aware of it as I can bet what SMA's stance will be now. But, we'll see.

I'm not used to being able to extend warranties of my own volition. It is usually part of the push of sales teams to drum up extra business. Mind you, plenty of mis-selling in that line of course is perhaps why it isn't done so much now.
But, I don't know what the sigma factor is in terms of the normal distribution or bell curve but I suspect I'm well over 3sigmas under the mean time between failure. The mean was 15years in 2011 and 5-10years in 2006. Was my equipment a refurbished item and hence typical of an older system is one question? The Sunny Boy 3800 was available several years before 2010. My installer assures me it was new. If the mean was 14 years in late 2010, in excess of 8 years seems awfully far away. 3 sigmas is 99.7%

If you go to the location below it says strong rights for 6 years. The Sales of Goods Act 1979 (as amended) in effect in 2010 had the same length of time.

http:// https://www.moneysavingexpert.com/insurance/cheap-free-warranties#rights
You have strong statutory rights anyway

When you buy anything, you will be protected by the Consumer Rights Act 2015. It says goods should be of satisfactory quality, fit to do the job intended and last a reasonable length of time.

Where goods are faulty, take them back within six months and this law means the shop has to prove they WERE NOT faulty when you bought them.

Even after that you still have strong rights for six years, but from then on you must prove the goods WERE faulty when you bought them. So at the very worst, if you buy, take it home and it doesn't work, take it back and you are entitled to a full repair, replacement or at least a percentage towards the cost of a replacement.

Martyn1981

Thanks folk for the warranty tip, but I'm hoping to replace the two inverters on my ESE with a single dualMPPT inverter as and when one of them fails.

It's a bit tricky as one string is 13 (185W) panels, whilst the other is 5 (235W) panels, so there is a huge voltage difference. However I've now found 2 inverters (ironically SMA and Samil) that have a voltage range wide enough to cope with both strings. The main problem actually wasn't the minimum voltage, but the minimum MPPT voltage.

Both inverters are 3,680W models, but I'm hoping to find something a bit smaller, perhaps 3.3 to 3.4kW to better match the 3.58kWp of panels.

My current inverters are 95% and 91% efficient, so I should get a boost from a newer (and better) inverter too, and sharing input may also speed up turn on time, and slow down turn off time too ..... not sure!

I'm not belittling the expenditure of a new inverter, but for earlier installs on high FiT, there's a lot more room for mistakes and 'lessons learned', which would be partly reflected in the higher income. For those installing now, there's less room for mistake, and hopefully the huge drop in inverter costs*, and better knowledge, will help.

*I seem to recall that during my install in 2011, the SMA 3600 dualMPPT couldn't quite cope with the lower voltage, but cost about £1,400 ..... Ouch! Even my 'ickle' SB1200 was around £500, but several small inverter models like that are now available for around £250.

Mart.

gefnew

Hi Martin
If you go to the sma website and take a look at the sunny design portal this may help in your future design of your system.
regards
Geoff

gefnew

Quick note Martin
I used this back in 2011 when looking at quotes and information the guys where spouting and just put there info in to give me at the time optimal arrangements.
Regards
Geoff

Martyn1981

gefnew wrote: »

Hi Martin
If you go to the sma website and take a look at the sunny design portal this may help in your future design of your system.
regards
Geoff

Thanks Geoff. I do have Sunny Design installed, used to use it a lot when chatting with folk thinking about installs on here a few years back.

It was also handy when one 'I'm an electrical genius' kept telling folk that an undersized inverter was the same as 'overvoltage' and could cause it to blow up.

I'm not joking, he used this argument multiple times to criticise my advice, the irony being that all of my inverters are slightly oversized, whilst his was slightly undersized. I chatted with SMA in the end, and they e-mailed saying that they might issue a cease and desist if he kept it up, but he went quiet after a friendly leccy engineer on here explained the difference. He's gone quiet now.

He was one of the original 'anti-PV/FiT boys', with a penchant for nuclear.


Back to my inverters, mine don't have the top of the range SMA shade management software, but I'm very surprised at how little loss I'm suffering. I think my ESE has a small but significant amount of shading, but generation is in line with the PVGIS gross figures. That probably sounds good ..... so far?

But paranoia has set in, and I don't know if the SMA's are doing a really good job, or nothing special, as I'd like to get a dual MPPT Samil to replace the pair. More efficient, one inverter, and nice and cheap ....... Oh what a dilemma. :think:

Mart.

PotentialEnergy

Martin
Don't suggest I know the ins and outs but do you risk leaving yourself vulnerable to both systems being out if something goes wrong with this single dualMPPT box? At present if one box goes, your other produces. or does this DualMPPT have built in resilience so it can cope with 2 streams if one part of it goes?