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Solar edge optimisers
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<blockquote data-quote="sjt01" data-source="post: 7259632" data-attributes="member: 30726"><p>A friend of mine is now working on solar installations, and is very sceptical. This was his response, although without hard financial figures:</p><p></p><p>Don't do it!</p><p>Or maybe do it in some circumstances.</p><p></p><p>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. </p><p></p><p>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.</p><p></p><p>[ATTACH=full]923370[/ATTACH]</p><p></p><p>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.</p><p></p><p>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?</p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>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).</p><p></p><p>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).</p><p></p><p>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.</p></blockquote><p></p>
[QUOTE="sjt01, post: 7259632, member: 30726"] 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. [ATTACH type="full" alt="image.png"]923370[/ATTACH] 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. [/QUOTE]
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