My installation has been running for 10 years, but is now experiencing some weird problems. Thought I would post here for some help?
The system consists of an array of 40 AstroPower 120-watt, 12-volt panels.
The system's 2 combiner boxes, 1 GFI array protection/breaker unit, 2 charge controllers, 2 SW 4048 invetrers and 2 GTI units are all Trace (Xantrex).
A single circuit Battery bank consists of 4 Concorde 12-volt, 255Ah, series-connected (48 Volts)
The array, combiner boxes and GFI are mounted on my house, the charge controllers, battery bank, inverters and GTI units are mounted in an enclosed storage area adjacent to my garage (35 feet away).
The PVs are divided into 10 groups (or circuits), each group of 4 panels is series-connected to obtain 48 volts.
There are (2) combiner boxes, capable of 10 circuits each. (5) PV circuits terminate in each of the combiner boxes, as the capacity of each of the charge controllers is only 40 amps (wanted some 'headroom').
The outputs from each controller connect to the single battery bank.
The battery bank travels through (2) 175 Amp disconnect switches (1 for each inverter).
My wife recently informed me that she heard loud 'buzzing sounds' coming from 'those boxes' at the back of the house. These would be the combiner boxes.
The problem only happens during daylight hours. The buzzing starts off as slight pulses (intermittent), then become longer and more frequent, a short constant buzz for 10 seconds, then the buzzing stops for a while (half hour ~ a couple of hours). The period of time of the 'buzzing' starts and stops varies in length - anywhere from 5 ~ 10 minutes.
I checked the utility meter and noticed it was not spinning backwards when this problem is occurring (not supplying power to the grid). After the 5 ~ 10 minute 'outage' the system returns to 'normal' operation and spins the meter in the correct direction (supplying power to the grid).
This happens several times during the day, but not on any particular schedule.
I for the life of me can't figure out why the combiner boxes 'buzz' ...
Has anybody else had this problem? ... know what is causing it? ... and more importantly, the fix?
Thanks in advance ...