A CDI should get around 14.2V at the battery terminals after being running for a short period. If you're not, it's most likely the main positive loom has got corrosion in it at the starter terminal. Check to see if you're getting over 14.2V at the alternator, then check for volt drop between the battery positive and the alternator main output.
You can either remove the loom, drill two holes in line with the end of the cables and using a blow lamp/oxy-acy torch run plenty solder through the crimps, or just get a new loom.


14.8V?
That's really only needed if you're bulk charging the batteries after they've been run down. And to acheive that voltage on that much capacity, will take a lot of current!
Provided the solar is doing a good job of reguarly keeping the batteries around 13.2-13.5V, the continual trickle charge should keep them conditioned.


You're not using AGM batteries are you?
If you are, then you'll need some way of limiting current when charging, otherwise they'll pull every last bit of power from the vehicle they can when charging. They absorb charge far quicker than conventional lead acid batteries, and the voltage doesn't rise until they've got that charge.
We maintain some vehicles that have had AGMs fitted on the vehicle, and I've seen a flat one sit pulling 20A from a battery charger for 30minutes before the voltage even creeped above 12V, and if you jump start one, you can hear the load on the alternator and the voltage gradually creeps up.