Usually means battery is low, if covering the panels when parked up always a good idea to have the batteries on a good quality charger which will just trickle away keeping it/them in good shape....................or at least turn 12v power off to stop drain.
Topray 555 1230 charge regulator manuals are easy enough to find on the internet. I suggest reading it very carefully- about 3 times should be enough.
Here's what I've found (after months of annoying beeps and unnecessary expenses)
This alarm is set to go off by default when your van battery goes to 10.7 volts. My experience is that this often happens at night. It probably means your battery is dying. A quick test will indicate a full charge but this may only be a 'surface charge' which isn't enough to run a load. Things may look ok during the day when the sun is shining but after sunset the battery may not be holding a load properly.
It could also mean something else is drawing a current - possibly a short circuit somewhere.
Either way it's time to visit your auto electrician. If your battery is an AGM (most likely) you should get a full load test but this means giving up the disconnected battery for 24 hours which is a hassle if you are traveling and off grid.
I also suggest you check your 240v battery charger and make sure it is set to the right battery chemistry (eg AGM). The wrong setting here can reduce your battery life.
Frequent discharges of AGM batteries (like when your regulator is bleeping) shorten battery life, so once this problem starts you are on a downward spiral with ever shorter periods between bleeping.
You can stop the buzzing by disconnecting the solar leads to the regulator. Black (negative) FIRST, then red (positive), though the latter may not be completely necessary. The ORDER you disconnect the leads is IMPORTANT or you could damage your regulator.
Don't tape over the buttons this can also cause damage to the regulator.
I can't remember exactly what I did when it started beeping one day- I vaguely think it was related to the load on/off setting when the left button has been pressed? So try pressing the left button then the load, or left button twice then load..or something like that
Hello @starcraft and @pharlap66 , just in case you do not have the full instructions for your Top Ray 1230 solar controller, here is the proper instructions for you to download. Please note that unless you have wires connected to the "Load" terminals, the display will NOT show discharge in amps, only amps IN and Voltage. I have provided wiring diagrams for this easy connection if you also want to know what current is going OUT of battery. But only simple if you do not have a Drifter panel, in which case, you should monitor the Drifter panel to see what is happening. By the time the Top Ray starts beeping at 10.8 volts, your battery is stuffed and probably beyond recovery to recharge and hold a reasonable capacity. 11.80 volts is the last stop before battery goes into serious decline, so the Low Voltage Disconnect at 10.8 volts is far too low IMO. For your info @Gonemissing .