yes def possible. But imo sunlight tanks are volitile. because you cannot regulate the amount of light the tank gets on any given day. most likley the tank will be algae ridden.
1wpg is about the lowest you want to go and still be keeping your plants alive.. 1.5wpg is about ideal for a low light tank... high light is anywhere from 2wpg all the way up to 4-5wpg, though IMO anything over 3wpg is overkill and you are just asking for trouble with algae.yeah i would be careful with sunlight. I keep all my blinds near my tanks closed during the day and just simulate sunlight for them with my tank light and turn it off when I go to bed. If I was you I would think about getting a light for the tank if you can afford to do it right now, I think the guys on here recommend 1 WPG (Watt Per Gallon) But I could be wrong, Dippy is the man you need to talk to. Good luck man.