Surges in voltage

[thirteen]

My neighbor has problems with his solar system. I had my meter on his solar and about every 1/2 hr there will be a surge of voltage going up from 10v to 30vs. It will kick out the 60a breaker ever so often but in no order of time, but nothing else. The amps seem to remain steady. There is a small fluxuatin in the battery voltage when in float but the batteries test out ok.  I think he has a bad cable somewhere in his system. any ideas? 24v system 1200 ah bank lead acid  2 Midnite controlers. There are 2 seperate solar panels some 40 ft apart. they all feed to one piont. 6 250 w 24v panels on one set , 6 - 180w  24v one the other set of panels. ?? 13

[SparWeb]

Where are you picking up 10 volts?  Nothing in the system should be below 24 volts.  When charging, between 25 and 28 volts.

"batteries test out ok"...  Have you measured the electrolyte SG?

Consider the possibility of a shorted plate in one of the batteries, even if they aren't very old.  A short in a battery plate could cause all of your problems.

[thirteen]

isolating one half. He still has an old 12v system hanging on the wall with  invertor, controler, and switch gear. That can easily be put back in service with just a couple of wires. It would isolate one half for a few minutes. I'm not ssure about his solar panels which are 24v I would think the controler would handle the load for a little while. He'll have to look.
I should have said he gets a rise from 10 to 30 volts just as a spike. so it would be around 34 to 42 volts spike. A fast count of 1-2
the electrolyte sg.  checks out
Jay from city electric gave me a heat gun to check out the heat in the batteries. He said it might save some searching if one show up hotter than the rest. A partially shorted plate sounds better than my cable thinking.
I'll be back up there Tuesday maybe he will have found something.
The only other thing would be a pissible controler failing just not sure.
Thanks for the input 13

[SparWeb]

10 volts still isn't normal.  It's a "very unhappy" number in my books.

After a 12v nominal lead-acid battery goes below 10.5v, its life is drastically reduced.  Is this the resting voltage?  Is it being loaded by the inverter when you measure 10v?

Loose cables can do intermittant strange things, but usually you can provoke the strange behaviour by wiggling the wire again.

[Frank S]

Like sparweb said loose cables or corroded connections will cause strange voltages
 if the panels are connected with MC3 or MC4 connectors a bad crimp in the cables leading to the combiner if he has 1 or from the use cable to the main lead cables.
 On my array I have 8 panels in parallel I made up 2 sets of 4 cable leads using 10 ga Use cable with MC4 connectors on 1 end then put the 4 opposite ends in a single 2ga terminal end crimped and soldered. then Connected  those to 2 ga copper run lead cables with SS bolts and copper washers .
 after the system had been in operation for a month I was noticing strange amperage readings on the display of my PWM It turned out that 3 of the MC4 connectors from the panels had poor crimp connections and were not soldered. SInce it was not feasible to reuse the connectors I replaced them with new and did it my way by crimping & soldering then coated with CRC aerosol dielectric grease before assembling the plastic housings
 Problem solved for me at least
  Any time I have ever had a phantom voltage or amperage anomaly in anything I have always looked first at connections
 With PV you should be able to use a known resistance dummy  load and an ohm meter  by  going up stream from the charge controller . It helps if you have a disconnect or  a fuse that you can pull to isolate everything from the array.
 Use a methodical process or elimination to locate a short or intermittent circuit   

[thirteen]

The batteries are not going below there voltage they go above it. The system was  and is still in use. It is a spike when they are being charged by the solar panels. When they are rest there is no readable spike. Nothing is adding up.   It only spikes when it is being charged by the panels. But we did not try his generator. There should be nothing there for a feed  from the genset. The genset has to be started by hand so it is not an automatic turn on and start. He starts it then throws the breaker on. He is replaceing all of the hoses so it is not runable at this time. 13
Things like this just makes life interesting.

[thirteen]

He is suppose to call me Sunday night if he needs any parts. I plan on going up there Tuesday. he was going to go thru everything today and tomorrow. I guess it is tomorrow already. 13

[southpaw]

Hi Thirteen
At which point in the system are you measuring the voltage spikes? 24V panels are capable of producing about 40V open circuit, if there is a poor connection between the charge controller and batteries you might get voltage spikes when the controllers cut in. If the poor connection was in the battery interconnects you would probably have a problem with the inverter cutting out on low voltage under high loads. 

As far as the breaker tripping, those panels are capable of producing very close to 80 amps.

[dbcollen]

with that small battery bank and fair sized array, it is probably just the controllers tracking the panels. most mppt controllers periodically track the mpp, when they do, the batt volts can spike

[thirteen]

the inverter does not cut out. The breaker tripping started him looking as to where it came from once he found the spike. getting it between the controlers and the batteries leading up to the inverter . The voltage coming out of the inverter stays constant maybe 2-3 volt drop change when a load hits it but stays well with in limets. I left a message for him to put his genset back together and try just using it for a couple of hours without the solar controlers working. That will eliminate the panel system all together. Plus get his batteries back up to full capacity. You have to drive 4+ miles to get cell phone service. No net service yet. I'll pass everything along mentioned here. Maybe one of Caspers relatives are visiting. (Ghosts). I'll be going back up there Tuesday morning. 13

[thirteen]

Just got off the phone and he found the problem. He disconnected the solar panels and fired up his genset. There was no problem it worked as it should have. So he went back to the solar system. He has switch gear to isolate everything from each other. On the large solar panel system he opened the disconnect box and used the heat gun on it and found it was hot. He opened  the cover plate and found that inside the blades on the disconnect were stuck and were arching. There was a broken spring or pin. I'll get him a new disconnect switch tomorrow and take it up to him Tuesday.  My question is is why did it show up after the controler unless it is going bad also?? He bypassed the disconnect and everything works as it should.
I've had a breaker go bad on a genset and the power was getting back fed thru the windings and would give you a wild leg that the voltage would be 1 1/2 times higher than it shouold be. We had another smaller genset that we used as a back up to supply power as needed.  The breaker was its isolation from the circuits.  I thought I would pass this along someone might be able to use the info. 13