One way to look at this is how many watts of panels will you need to make all the power you consume.
Another way to look at this is how many watts of panels will you need to keep your batteries happy.
Though related, they will not be exactly the same value.
I tend to think
batteries are your single most expensive component, so you should scale your system to how to keep the batteries healthy. As a general rule of thumb, you want to charge at a certain rate related to the capacity of your battery. Those would be....
A low rate of 1/20 of C or 0.05C. At 12V that works out to be 395Ah X 0.05C X 13V charging X 1.2 fudgefactor = 308W. Call that 1 300W panel. This rate may or may not keep up with demand. Expect it to take two days for a full charge.
A medium rate of 1/10 of C or 0.1C. At 12V that works out to be 395Ah X 0.1C X 13V charging X 1.2 fudgefactor = 616W. Call that 2 300W panels. This rate may keep your batteries fully charged every day.
A high rate of 1/8 of C or 0.125C. At 12V that works out to be 395Ah X 0.125C X 13V charging X 1.2 fudgefactor = 770W. Call that 3 260W panels. This rate will charge fast, and still provide a bit of power on less than optimal days, when there's some cloud cover.
You can get cheap 250W grid-tie panels now in the range of 50-55$ per panel, so there is no good reason anymore to not try to maximize your wattage. With a good MPPT controller, you could wire three 30V panels in series to feed
the controller, which will transform the raw high solar voltage down to the 13-14V your batteries need to charge. I personally would go with the third 1/8C option.