system intermittantly switching off

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system intermittantly switching off

Postby judoal on Fri Jul 14, 2017 12:30 pm

I have an older system with 3 GVFX3648 inverters, 4 MX60 charge controllers, and a Mate2 with 10KW of PV panels. The batteries on the system are beyond their useful life and don't hold a charge for more than a couple of hours. If grid power goes down, there is zero backup power even though at the time, the batteries are registering adequate voltage to at least provide minimal power. I am waiting to be able to afford new batteries. The problem that the system is having is that every once and a while, it switches off power to the house which gets restored about 10 seconds later. This generally happens while the sun is shining. House loads are minimal but I don't have any information if the event happens when something like something turns on that draws current. All of the high current loads are not on the critical load panel except for the pump in my cistern. Since I don't have battery backup functional I am unable to review the logs (Wattplot) to see if I can determine the source of the problem. I am guessing that it is either the batteries or one or more of my inverters failing. The only warning condition is that one of the inverters (not the master) needs to have the temp sensor replaced, but otherwise it seems to operate normally, even when the sun goes down or is hidden behind a cloud. Switching from solar to grid is usually seamless. Any ideas out there about why this is happening or what I might look at to resolve this issue?

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Posts: 24
Joined: Tue Mar 24, 2009 3:24 pm
Location: Nederland, CO
My RE system: 3 GVFX48, 4 MX60, 30 SolarWorld SW 175, 12 Sharp ND-208U1, 12
Sharp NT-S5E1U (185 Watt) panels, all pole mounted, 16 Deka 8G31, 12 volt, 98 amp-hour batteries, grid tie

Re: system intermittantly switching off

Postby hendrik krijt on Sat Jul 15, 2017 4:24 am

Hi judoal,

I have 3x FM80 charge controllers and I am not familiar with the MX series, but on my side it sometimes happens that they all do a wake-up, rescan, new voc. rather simultaneously. If I have a number of high loads running, I suddenly have to load-shed them. (I have a separate load control system not integrated into the outback system), it then detects a sudden volt drop on the batteries. Could it be that you get a similar situation, with your dead batteries, that cause your inverters to die and not being able to "think" till the MX's have finished scanning and return power to the system, and the batteries, and the invers' brains. Could this result in your "dead" spells? Perhaps your inverters are taking their time to synchronize to the grid due to low batteries, and while in the process the voltage is gone and it cannot even think what to do next as it needs battery power to think?

Lots of South African Southern Sunshine to you all!
Hendrik Krijt
hendrik krijt
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Posts: 32
Joined: Sat Dec 31, 2016 6:33 am
Location: South Africa, KZN province
My RE system: pv=4.9Kw, 2xflexmax 80, 2x 24v-240v 50Hz outback inverters, fla's 12x Willard rt25 tubular 2v cells. rsa, kzn prov. (may change to aquion batteries)

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