I have had my system installed for 2 and a half years. last week the breaker tripped and the battery stopped charging/discharging. I reset the breaker, but the same thing has happened another 2 times in the last week.
This has never happened before.
The 1st event was BMS Communication Failure
then the following event was Battery voltage low
breaker tripping,
What kit have you got?
Which breaker?
Breaker on side of battery?
Mains breaker in consumer unit. What type RCD? MCB? RCBO?

If it's the DC breaker between the battery and the inverter then the Battery Voltage low is a consequence of the breaker tripping. If it is this breaker there is some more detailed advice in earlier forum messages but basically your connecting screws in the the breaker may be loose and need tightening or your DC breaker is failing.
Similar thing happened to me just before GE demise. I got National Grid out who confirmed that the voltage was within limits, which eliminated one issue. Transpired it was the breaker at fault, which got replaced a few days before GEs administration. National Grid came out the same day I asked.
Windy Miller
Hi - this happened to me in February after a third battery was installed.
It turned out to be bad connection with the main DC breaker - the two large fat cables need to have a proper D-shaped ferrule crimped firmly so it fits properly into the brekear slot
AndyZ900rs do you have a photo and who fixed it?
this company - south wales https://www.theelectricalgroup.com/ - contact is Craig - great job!
No photos I am afraid