Solo is only allowed until Gaumukh. For Tapovan, you need a guide. You can not remt anything im between, you have to take all necessary things from Gangotri
That said, in bhojwasa, there are couple of places to stay, which you have to book in advance from the national park office at the starting point of the trek. In tapovan, there is a Mauni baba hut, however he usually doesn't allow anyone to stay in there