Pwm solar controllers

Chester.
A longtime ago I has a similar experience with a PWM unit. The screen wasn't black but the voltage was too high.
If you have the battery negative AND the solar Negative wire connected together somehow, ( most people think all negatives join together but they don't.) the solar regulator uses the Negative solar li=ine as the interrupt, ie, PULSED LINE, in the PWN controller. IF the negative solar line is also connected to the battery negative, it eliminates the PWM action ability and the SOLAR panel will give all it can to the battery, hence overvoltage reading.
First thing is to MAKE SURE all solar negative connections ARE NOT connected to anything else, only the regulator/controller. These systems use MOSFET transistors positioned IN the negative side of things and if the solar negative and the battery negative are touching each other, the MOSFET control, ie, the PWM ability is NEGATED . Actually it is shorted across it's MOSFET and becomes a path for electricity instead of a controlled by pulses path. If the unit has been HOT then it's screen might still be OK if disconnected and cooled and the above precautions regarding negative paths are observed. Hope this all makes sense.

Yes to both, OK to go bigger and OK to leave in sun disconnected.

Chester : I also had a solar controller that was faulty and pumping 16 volts into my battery so I bought victron mppt wifi 15 amp ( from solar 4 RVS at a very competitive price) for my 200w panel that i have mounted in box on back of tray back ute , not a fancy set up ,
I can read the solar data on my phone w victon app that works well no need to open the box that way.

I am not by any means a solar expert just the way I set it up including with suggestions from this forum .

As pointed out it probably is postive ground, if you checked the voltage by placing the volt meter negative on ground and the positve on the output of the regulator it will show panel voltage.

Was the vlotage you measured across the battery terminals, if so then yep the regulator is kaput.

Andrew, the "Load" circuit is provided for connection of non-essential loads that will be disconnecteted should the available voltage falls to a low level, giving prerence to more essential loads. If you have no need of it them just ignore it..... no bad things will happen.

As to the significance of " negative switching" regulators, this is simply a more convenient style of manufacture and has no significance to the connection or use of the output PROVIDED that no connection is made to earth of the input to the device AS WELL AS THE OUTPUT of the device as this would bypass the regulation. In other words... do not earth your solatr panels ahead of the regulator and all will be OK.

As mentioned, it's likely positive ground. If you tested the voltage by placing the voltmeter's negative lead on the ground and the positive lead on the regulator's output, it should display panel voltage. Did you measure the voltage across the battery terminals? If so, then yes, it seems the regulator is indeed malfunctioning.