Sounds like a battery issue... run down too far. Typical of pretty much any solar charger.
IS this your fencer? The guage on the front there is supposed to tell you how much charge is in the battery. Here's their instructions for that:
When the Mag 12 SP is first turned to ON position, the performance meter on front of fence charger now performs 3 exclusive functions: 1. Meter operation test 2. Battery charge level test 3. Fence charger voltage output on fence.
1. Meter Operation Test: This test will sweep meter needle to full scale and back. This test shows that meter movement is smooth and able to indicate full scale. If meter is functioning correctly the needle will go to the top of green (full scale) and then return to bottom of red.
2. Battery Charge Level Test: The meter will indicate the charge level of the battery. If the meter indicates "RED" the battery should be recharged before operating fence charger. If the meter indicates "YELLOW" the battery is low and should be recharged soon. If the meter indicates "GREEN" the battery has a good charge. To get the most accurate reading of the battery charge level, the battery should be in a no load/no charge state. Battery charge level will be indicated for the first 5 seconds immediately following the Meter Operation Test.
It has a 12-volt internal battery, but you can also hook up any 12 volt car/tractor/RV battery to it too if you want to. I'd recommend a deep cycle type. Lots of guys keep two, and then just keep switching them every so often, and recharging at home as needed.
I have 0 confidence in solar chargers... Aside from the eternal battery issues, they're ALWAYS minor players as far as oomph on the line... they have to be, or they'd drain the battery too fast... which they already have problems with. This Parmak states a MAX joule rating of 3.1, and the "regular" joule rating of 1.1... and then they call it a "30 mile fencer". That's like "nothing" basically.............. That having been said, it IS one of the "larger" solar fencers available. I have a 58 joule Gallagher5800i (plug in charger), rated for 87 miles of "typical fence" (430 miles of perfectly clean fence...). That's meaning "miles of wire"..., so if you've got a 4 wire fence, reduce that number by 75%. Fencer company "miles of fence ratings" mean absolutely nothing. TSC is a rebranded Zareba... and they will have different "miles of fence ratings" on the same model fencer. It's the joules... or amount of energy the fencer is capable of throwing down that line, that counts.
If you have ANY "drag" (shorts along the line somewhere, grounding through wet weeds, or even just damp air...), you'll be asking alot more from your fencer... and it'll end up draining the battery, even if you do have sun. That "drag" is measured in amps... a good fence tester/short locator will tell you how much "drag" your fence has at any given time... the locator will direct you toward the short as well. My Gallagher reads out the "drag" right on the fencer in amps... I have ALOT of fence running on it, some 3 wire, some single wire. On a dry summer day, it might be reading like 25 amps "drag", on a foggy day on the very next day, it might be reading over 100 amps.
You need JOULES to overcome that... and if a "solar fencer" had that much power, it'd drain the batteries way too fast. IMO, if reasonably possible to accomplish at all, spend more and get a good plug in, and use the Parmak as a back up in places you might need it, or sell it on FB Marketplace. Your goal is to keep the critters in reliably...
Parmak Magnum Solar-Pak 12 Electric Fence Charger
12 volt – Solar/Battery Operated – 30 miles