First time energy setup advice? (battery+solar)

It is a concern and why you might want to consider a couple of 6 volts. They are more giving. And you don't want a 12 volt car battery. You want a 12 volt deep cycle battery. Whether you go 6 volt or 12 volt, plan on spending at least $75 or so on just one battery. 6 volt batteries will be a little more. You are talking several hundred dollars or more just for a solar hook up of the size you mentioned. Not to include installation if you have someone else do it.