question

carlos-farfal avatar image
carlos-farfal asked

Why is my off grid system shutting down overnight?

Hi: 
I have an off grid system consisting of 6 270W panels, 1 Victron Phoenix of 500VA / 48V, a Blue Solar 150/35 48V regulator and an 8x100Ah battery bank in two series of 48V each. The loads are luminaires of a corridor (210W installed) that must be turned on when the darkness of the afternoon starts and off at dawn, however they go out between 1 and 3 in the morning. 
I checked the sizing and it is fine, what I don't know, is if there is any voltage parameter that is incorrectly configured in the inverter or regulator, and that causes the system to shut down, due to low voltage maybe. As a background, the maximum battery voltage during the day reaches 57.5V and the minimum voltage, when the charges are switched off is 37.44V. 
I would appreciate comments to someone with more experience in this type of configuration, to see if I can solve it. 
Thanks in advance,
battery chargingPhoenix Inverterbattery system voltage
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4 Answers
carlos-farfal avatar image
carlos-farfal answered ·

Last night I measured the batteries of two off grid systems, after it turned off completely. At sunset 9:15 p.m., the interior luminaires were turned on and the voltage was 51V. Then, at 1 am, the voltage dropped to 36V and the system stopped working. At that moment, we desconnected all the bateries bridges and proceeded to measure voltajes of each battery individually. Batt1=7V ; batt2=12V ; batt3=7V ; batt4=12V ; batt5=5V; batt6= 12V ; batt7=10V ; batt8= 12V

And other Off Grid System:

Batt1=10V ; batt2=12V ; batt3=12V ; batt4=10V ; batt5=12V; batt6= 10V ; batt7=10V ; batt8= 10V


Than you for advance. @Guy Stewart (Victron Community Manager)

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

When the system is shut off at 37.44V, check the individual voltages of each of the batteries with a multimeter and see if they are all consistent.

Write down the voltages and report back.

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Murray van Graan avatar image
Murray van Graan answered ·

It does appear that the battery bank is not coping with your load. Further, batteries discharged down to between 7-10Vdc will certainly damage them. You definitely need a battery balancer, to keep all batteries at the same level. Ultimate solution would be to replace them with lifepo4 batteries

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loramoser avatar image
loramoser answered ·

is the inverter and it's fuse wired to the battery terminals, or to a Load terminal on the charge controller ?

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carlos-farfal avatar image carlos-farfal commented · 
The inverter and its internal fuse are connected directly to the battery bank through a 6 mm2 solar cable. In turn, the output of the regulator is connected to the battery bank through a 6 mm2 solar cable
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