I agree. The fully charged battery will be between 12.6 and 12.8 volts. You can get a good reading on this only after the battery has lost its "surface charge," which is an unevenness in the concentration of the electrolyte. To remove the surface charge, let it sit for at least four hours to allow for the surface charge to dissipate. (Or, if you have a battery load tester, apply half the CCA rating for fifteen seconds and then wait 5-10 minutes.)
You'll routinely find voltages all over the place when the battery is charging: in the low to mid 14s during the bulk charge phase, in the mid 13s for the float phase, and the 12s when sitting. You'll also get all kinds of different voltages when you have a load on the battery . . . hook a big inverter to it and turn on a microwave or resistance heater and you can see voltages in the high 10s. (As an aside, big fast discharges will reduce the amount of capacity available. Discharge a 100 AH battery for an hour at 50 amps and you'll have considerably less than half the capacity left. You can find the science on the internet.)
The point being that if the ArkPak battery is, say, hooked up to the car or mains charger and has some loads attached, don't pay too much attention to the panel voltage reading if it's not something in the 12s. Try to get a charge back on it before it hits the 11s; 12.0 volts is about 75% discharged.