Solar edge optimisers

Exfarmer

Member
Location
Bury St Edmunds
Has anyone got any hard reliable figures for improved out put from the use of this system.
We are currently looking at stripping a roof and refitting for various reasons and it has been suggested, that it is an ideal time to fit them. Sadly we do not need to replace the inverters for any other reason
 

sjt01

Member
Mixed Farmer
Location
North Norfolk
A friend of mine is now working on solar installations, and is very sceptical. This was his response, although without hard financial figures:

Don't do it!
Or maybe do it in some circumstances.

The systems may be marginally higher producing, we would have the data to prove it one way or the other. It would be interesting to do the analysis some time. In my opinion they cause more problems than they're worth.

The good thing is that when there's a problem it's obvious which panels have issues. It's definitely better when you've got a complicated site with shading because you've effectively got a maximum power point tracker for every panel or pair. That also means you get per panel/pair generation data and when there's a faulty panel or optimiser then the monitoring shows that very clearly. On this picture you can see optimiser 9 on inverter 4 has generated nothing today.

image.png


For all these panels on a uniform roof with no shading who knows why some generated 72Wh today and some were only 56. A bit further along that roof there are some that did 82Wh today. That's a flat roof with no shading. Maybe one has a birds' nest nearby and so is covered in poo? The ones that generated 0Wh on this roof are due to a faulty optimiser. This is a 2 year old system, 120kWp and has two faulty optimisers. That's one of the better systems, a failure rate of 1% on that roof. Taking the whole portfolio that use Solaredge I'd guess that maybe a 2-3% failure rate was typical with an average age of about 18 months. I haven't done the maths, but almost all our SE sites have had optimiser failures and some have had multiples.

If you're living on site, don't have to travel to fix it and have a flat roof that's not a problem. If you're managing it remotely and need to use scaffolding then the optimisers will likely just remain broken until enough have failed that it's worth fixing. I've got two sitting with me at the moment waiting for me to be driving past a site with some free time. If you do the maths on a 900kWh/kWp/year site, a 600W faulty optimiser will lose 540kWh per year. If you're using that power to substitute imported electricity at 11p/kWh that's £60/year. By the time you get on the roof, find the faulty optimiser and check that it really is the optimiser at fault it takes at least an hour if your map is accurate. You then go home, order another one and repeat the process. It's at least two hours of labour to fix one on a flat roof (1 hour diagnosis, one hour fix). Plus travelling. How much does an engineer cost? How much does an engineer cost if you're buying one in from an O&M company?

If you go back to the picture above it would be great to find out why there's such a relatively huge difference in production. Maybe it was just today? But again the investigation would cost you more than you'd gain from it. All the data exists if you want to look into it. If you've got access to a fancy pants AI system that can go through it all in a blink then it's more useful.

Optimisers aren't the only things that can go wrong, I'd say so far the most common cause of faults that I've seen are dodgy connections that have let water in so are causing high earth leakages or have gone so badly wrong they've burnt out. In some cases having optimisers can help in finding those faults but actually having a load of extra electronics on the string makes doing tests a bit more confusing. It's nice that when they detect a fault they drop the output voltage to about 1V per optimiser, it's safe. However it does mean you can't measure the earth to string voltage to pinpoint where a break has happened so easily.

Dodgy connections are probably one of the more common problems on a roof, so in my opinion you probably want to minimise the number of joints. In a normal system you have a plug and a socket per panel. In a SolarEdge system you have that, plus two plugs and two sockets per optimiser. Two connect to the pair of panels, two for connecting to the string. So you're doubling the chances of one of those connections failing.

If you have a panel failure on a non SolarEdge system there's a pretty good chance you wouldn't notice it. You could go through each panel in turn checking it's OK but I don't know if that's worth the time. Perhaps once every five years. This is an advantage of SE as it's obvious when there's a failure (even if it usually is because of SE).

Finally you're tying yourself in to using SolarEdge inverters in future (unless you want to go back and rip out all the optimisers when your inverters die).

The remote monitoring is nice though. For a site with complicated shading, on site staff and easy access then go for it. For a remote site or with tricky access then no.
 

f0ster

Member
we have installed about 18 container loads of pv over the years and there has not been any panel failures that we know of, quite a few inverters going down after about 5 years of use, panels are quite reliable, they are simple technology and usually do what they are supposed to, it is the electronics you add to them that gives failure, as mentioned above if you have a shaded roof you might justify micro inverters but you are multiplying the potential failure rate, instead of just one or two inverters you are installing lots of them, any one of them has the potential to fail, we replaced a 6 year old inverter recently with a one twice the size of the existing, we also fitted 20% more panels on to the spare inputs of the new inverter, more production, the customer was going to inform his energy supplier but for just 20% he might have forgot, he did give the old panels a good clean because the new strings were more than double the output of the old ones due to a large build up of dust, he had a farm track right next to the panels location,
 

curlietailz

Member
Arable Farmer
Location
Sedgefield
I have SolarEdge and I really like it
I like the monitoring aspect and all the stats and charts and the fact I can see each panel and how it’s performing
Having two strings and two inverters means I can compare them to make sure they’re working
Not sure if it’s cost effective though !
 

Exfarmer

Member
Location
Bury St Edmunds
I have SolarEdge and I really like it
I like the monitoring aspect and all the stats and charts and the fact I can see each panel and how it’s performing
Having two strings and two inverters means I can compare them to make sure they’re working
Not sure if it’s cost effective though !
How big is your system?
 

SFI - What % were you taking out of production?

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Red Tractor drops launch of green farming scheme amid anger from farmers

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As reported in Independent


quote: “Red Tractor has confirmed it is dropping plans to launch its green farming assurance standard in April“

read the TFF thread here: https://thefarmingforum.co.uk/index.php?threads/gfc-was-to-go-ahead-now-not-going-ahead.405234/
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