Charging 4 12-volt house batteries with portable charger

RoyB wrote:
The BATTERY SCIENCE rules for charging a depleted 12VDC battery in a short three hours time is to hit it with 14.4VDC for two hours and then 13.6VDC for an additional hour.

That last hour at 13.6V is where solar comes handy. Pretty much any panel will generate enough amps to keep it at 13.6V.

It will also help keeping batteries from becoming too deeply discharged, so there would be less need to push a lot of charge in there in a short period of time.