Solar charger I use and here is the battery pack. You do not need sun you need very bright light. At the cottage we have a skylight which is ideal for me to place the panel when charging the battery pack. 8 hours of charging per day was more then enough to keep me going for the 3 weeks we were at the cottage. With the battery pack the charging time of the iPad is the same as connected to the wall charger. It also kept an iPhone charged during the same period.