smkettner posted a link to a group from a site others have used. Here is one of the 160w kits available.
160w kitWe use a simple 230w portable system. It kept a grp 27 battery up for a week and we use more power than you are thinking. It was also not all that sunny, by 11am or noon the clouds had moved in. That was more than enough to replace our day to day needs. I would check the voltage of the battery when I got up in the morning and the lowest I saw was 12.5v. That's if I caught it before the system woke up and started charging.
We could go like that forever but we have extra battery for when the clouds wont co-operate for a week or so.
Actually for a few days a week and with as little power as you are suggesting, a few batteries should last you. You will just have to take them home in between and charge them.