Solar panel drop outs

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Hi we recently had solar panels installed and using the monitoring app have noticed regular drop out lasting approx 5 mins each time. The company say it is normal and blame cloud cover. I do not agree as sometimes it has happened when there are no clouds and I do not believe energy production would drop to zero even if there were clouds. Also they always last approx 5 mins. Almost as though something is tripping and restarting.
I have included an example below




Please advise me on whether this is normal or indicates a fault.
Thank you
Philippa Chalk
 
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I can't see anything attached.

One possibility is that the main grid voltage is getting too high whilst the pannels are producing power.

If the mains voltage gets too high the solar pannel inverter will cut out for safety reasons.
 
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The inverter is tripping out.
Under periods of bright sunshine, power flows in the distribution network change or even reverse - such that voltages at your supply point rise. Unless the DNO has adjusted their network to compensate, then the voltage may exceed the upper limit laid down in the standards.
All embedded generation systems are required to have "anti islanding" protection. Basically this means that they must not try and feed an isolated section of network - whether that's just your own house, or the street, or even the whole village - should the bit of the network it's connected to become disconnected from the national grid. In theory, without such protection, it would be possible for a such a section of network to remain powered by the embedded generation with significant risks of equipment damage (eg re-closing a tripped breaker when the voltages aren't synchronised) or injury (eg to DNO personnel working on what should be a dead circuit).

So each device must detect such a situation - and the terminal voltage going outside of limits would be one factor in this. So bright sunshine, voltage rises, inverter trips out until it decides the situation is resolved.
My brother had exactly this problem, and the suppliers adjusted the limits to stop the trips. Go back to the installers, tell them they are spouting male bovine excrement and to adjust the limits. It may mean contacting the DNO and getting them to adjust their network. Either way, your installer should understand this and be able to sort it. I do however suspect that many installers have no idea how any of it works - and so will fob you off with any old story.
 
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That’s what I thought but the installers are insisting it is. I contacted northern power grid about voltage spikes and they advised getting installers out to check our equipment and said they could also check the voltage. If it is outside normal range they will investigate.
I will have to be more assertive with the solar panel installers I guess.
Clouds wouldn’t make the output zero would they unless they were very thick and black and they wouldn’t pass over in 5 minutes!
 
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Either they know it’s not clouds and are lying to me or they don’t know what the real issue is. Not sure which option is worst
 
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Either they know it’s not clouds and are lying to me or they don’t know what the real issue is. Not sure which option is worst
As has been suggested, I strongly suspect it's a bit of both - they don't know what the real issue is, and so are 'pulling out of the air' (and maybe even believe) the best think they can think of ('the cloud'explanation').

I wouldn't mind betting that, when they were wearing their marketing hats, the same company would 'reassure' you that the energy production would not fall to zero even if (during daylight hours!) there were 100% cloud cover.

Kind Regards, John
 
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Had another drop to zero this morning and it’s just blue sky so I will give them a ring this afternoon. So I have to insist they come and have a look? I fully expect them to fob me off and tell me to contact northern power but I will stick to my guns.
Thanks for your help.
 
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Tell them you have contacted Northern Power and they say/suspect the fault is with the installation. If you don't stand firm this will just keep getting backwards and forwards until you give up and just accept the situation.
 
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That readout is showing that the grid voltage (253.2v )is too high in your area that's way your inverter is shutting down, as it is meant to.

Your installers should get the grid involved.
 
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Any other houses in the area with solar, or solar farms?
 
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