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Solar Controller over-voltage cutout problem


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Hi All

 

Our solar pv has recently started cutting out due to, what appears to be, an over-voltage condition. It goes off (zero amps) for approx 5 mins then comes back on and behaves normally, until the next time (which is all too frequent on wash days). The Epever 40A controller shows a 22.5v 'battery maximum' on the days we have this problem but the battery monitor shows a normal maximum circa 14.7v. This only happens when using a moderate intermittent load, most frequently when using the twintub. The rest of the time it ticks along fine just as it always has.

 

I'm just wondering what might have gone wrong (whilst hoping for a miraculous solution AND researching new controllers)! We did add another 320W to our existing 500W this Winter so the controller is clipping now we're 'in season' but the manual says it's good for 2 (or 3 depending what you read) times the stated capacity of 520W. I've checked and fiddled with all the settings in a bid to resolve it but the best I managed was by disconnecting some of the panels to reduce the input. However, that didn't completely solve the problem but just  reduced the frequency a bit.

Any ideas guys, apart from getting a new (and better quality) controller! ;)

 

Thanks

Richard

 

 

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Last weekend we have recenty had a problem with the solar - the MT50 display would be perfect, charging good volts, good amps, then suddenly it would 'pop' and go off.

 

Went thru the wiring couldn't find a fault, checked the fuse, passed continuity, checked the batteries 'normal' 13+ volts.

 

Checked the solar output 100-110v - no problem

Checked the controller output 25v - strange ?

 

Spoke with Bimble technical guy who spend (seemed like) hours talking me thru fault finding and eventually suggested it may be the internal fuse in the controller which is not 'user replaceable' but can be if you want to open it up, find it, desolder and solder in a new one.

 

Went all the way thru the wiring again, new fuse, new fuse holder still the same.

Completely rewired from the controller to the batteries, still the same - THEN - the MT50 'came back' wonderful, got to about 10amps going into the battery and 'pop' off it went again.

 

Repeated all checks - another new fuse holder, and then noticed that the negative wire from the controller output was loose - jiggled it about and the MT50 came on, went off, came on. Tightened it up (I'm sure I'd tightened it in all the previous tests and replacing cables) and everything working perfectly.

 

Today in the sunshine 110v out of the (170w) panel, 14.6 volts at 10 amps (146w) going into the batteries, happy days. Working all day !

 

Check all you connections.

 

Basically, my problem was the epever controller was not connecting to the battery (loose wire) and defaulted to 25 volts output.

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Wow that's unbelievably similar! I did notice today by chance, whilst watering the batteries, that the circuit breaker/fuse on the solar positive was somewhat warmer than I expected but ran out of day to explore that avenue. Guess what I'm doing first thing tomorrow!

 

Absolutely brilliant!

Many Thanks

Richard

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50 minutes ago, Richardcn said:

We did add another 320W to our existing 500W this Winter so the controller is clipping now we're 'in season' but the manual says it's good for 2 (or 3 depending what you read) times the stated capacity of 520W.

 

Post a link to the manual for your exact model of controller please, and more details about your solar array - what is the maximum voltage the way it's wired?

 

I've installed quite a few Epever controllers and I've not yet seen one that can handle 2 or 3 times rated power.

 

All of them can be overpanelled within voltage limits, but they do specify the maximum wattage allowed.

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9 hours ago, Richardcn said:

the circuit breaker/fuse on the solar positive was somewhat warmer than I expected but ran out of day to explore that avenue.

Is that between the panels and controller or panels and battery. There are some types of breaker/ fuse sold for solar that are known to be poor such as the types shown, giving high resistance due to poor contacts. Post a photo of the breaker and we may be able to advise.

 

 

s-l1600.jpg

s-l1601.jpg

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At the risk of derailing the topic, does any one have anything to say about these 10x38mm fuse holders and fuses for high voltage series strings of solar panels? I'm helping with an installation where the voltages are sufficiently high that we want to prevent a chance of fingers touching anything live before the mppt controller. How reliable are they? I'm guessing reasonably so, since they are used in commercial solar arrays.

https://uk.rs-online.com/web/p/fuse-holders/8207259

I've linked to RS, but other suppliers are cheaper. RS do good photos and data sheets though.

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12 hours ago, TheBiscuits said:

 

Post a link to the manual for your exact model of controller please, and more details about your solar array - what is the maximum voltage the way it's wired?

 

I've installed quite a few Epever controllers and I've not yet seen one that can handle 2 or 3 times rated power.

 

All of them can be overpanelled within voltage limits, but they do specify the maximum wattage allowed.

I'm well within all voltage and wattage limits, I was careful to check that before adding the extra panel but you have to check these things whenever you get a issue. With Alan's similar experience I'm hopeful that I have a wiring issue, possibly a faulty circuit breaker. Just waiting for the rain to stop so that I can disconnect the solar up top and check.

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3 hours ago, PeterF said:

Is that between the panels and controller or panels and battery. There are some types of breaker/ fuse sold for solar that are known to be poor such as the types shown, giving high resistance due to poor contacts. Post a photo of the breaker and we may be able to advise.

 

 

s-l1600.jpg

s-l1601.jpg

Controller to battery (near the battery) and it's one of those in the bottom of your picture. Supplied to me by Bimble when I knew nothing worth knowing about solar. My recent research for a replacement had already led me to look something different! Probably just a standard fuse arrangement.

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1 hour ago, Richardcn said:

On the subject of circuit breakers and fuses, what are people using and what do people recommend? I want to replace mine no matter what I find!

For me when I fit stuff to my boat  anything that is Ultra Low Voltage* is on a fuse. Anything that is Low Voltage** is on an MCB. So all my 230vac stuff is on MCB all my DC stuff is on fuses.

Helps to know that if it's an MCB it's going to hurt if you get it wrong.

There are many MCB that are not rated to work with DC

 

*ULV =less than 50vac / 120vdc

**LV =less than 1000vac / 1500vdc but higher than ULV

 

Edited by Loddon
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27 minutes ago, Loddon said:

For me when I fit stuff to my boat  anything that is Ultra Low Voltage* is on a fuse. Anything that is Low Voltage** is on an MCB. So all my 230vac stuff is on MCB all my DC stuff is on fuses.

Helps to know that if it's an MCB it's going to hurt if you get it wrong.

There are many MCB that are not rated to work with DC

 

*ULV =less than 50vac / 120vdc

**LV =less than 1000vac / 1500vdc but higher than ULV

 

Thanks for the suggestion.

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1 hour ago, Richardcn said:

Controller to battery (near the battery) and it's one of those in the bottom of your picture. Supplied to me by Bimble when I knew nothing worth knowing about solar. My recent research for a replacement had already led me to look something different! Probably just a standard fuse arrangement.

Mine just goes through a midi fuse in a plastic holder.

  • Greenie 1
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36 minutes ago, Alan de Enfield said:

 

 

Yes - you might get better connections if the screws were 'IN' the fuse and not lying next to it.

Sounds like a prison related joke to me!

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I replaced the cheap CB/Fuse with a midi fuse holder and I'm pleased to say that it looks like the problem is solved. I'll give it a week and another wash day before I'm 100% convinced but it's lookin good. I only had a 40A fuse to hand but that'll be fine until I can get a 50A as we never draw anywhere near that.

 

Many thanks to everybody for their assistance particularly Alan for his invaluable help.

 

Richard

  • Happy 1
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2 hours ago, Richardcn said:

I replaced the cheap CB/Fuse with a midi fuse holder and I'm pleased to say that it looks like the problem is solved. I'll give it a week and another wash day before I'm 100% convinced but it's lookin good. I only had a 40A fuse to hand but that'll be fine until I can get a 50A as we never draw anywhere near that.

 

Many thanks to everybody for their assistance particularly Alan for his invaluable help.

 

Richard

It would seem that both you and Alan shared the same issue of an unnoticed loosening of screws clamping stranded wires. As the engine vibrations are strong in the electrics cupboard, it might be a good idea in all cases to use  bootlace ferrules on the wire ends, giving a better 'bite' surface for the screws. And possibly to check tightness on such essential connections as part of the check-up routine.

I'm saying all this to remind myself to do such when I install my solar setup next month!

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1 hour ago, Puffling said:

It would seem that both you and Alan shared the same issue of an unnoticed loosening of screws clamping stranded wires. As the engine vibrations are strong in the electrics cupboard, it might be a good idea in all cases to use  bootlace ferrules on the wire ends, giving a better 'bite' surface for the screws. And possibly to check tightness on such essential connections as part of the check-up routine.

I'm saying all this to remind myself to do such when I install my solar setup next month

Actually mine was a faulty circuit breaker/fuse but those ferrules do look useful nonetheless.

 

Good luck with the solar installation next month.

  • Greenie 1
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11 hours ago, Richardcn said:

I'm well within all voltage and wattage limits, I was careful to check that before adding the extra panel but you have to check these things whenever you get a issue. 

 

I don't think you are if you insist the controller will take 2 or 3 times rated power.

 

What model of solar controller do you have please?

 

 

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8 hours ago, TheBiscuits said:

 

I don't think you are if you insist the controller will take 2 or 3 times rated power.

 

What model of solar controller do you have please?

 

 

Epever BN4215 40A. Trust me, the manual states that you can install 3 times the 520W rating thus 1560W on our 12V system. We have 820W of panels running at under 40V. Clipping is, I believe, the term used to describe what the controller does when the much used practice of overspec'ing panels to extend into the less productive seasons (among other reasons) is employed.

Screenshot_20220521-085032_Xodo Docs.jpg

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I have same (but the 20a).

 

It was explained to me :

It is designed so that you can have a huge amount of solar (3x) so that it just uses/ provides its rated wattage in the Summer but due to the reduced panel outputs in Winter you can use 3x, but still get a useful amount.

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