Solar panels range from those that are cheap to those that are thin and flexible to those that are the most efficient. The cheapest tend to be the least efficient, but they required less energy to manufacture and are perfect for light applications such as trickle charging a battery. Small and flexible are not the most efficient in spite of their incredible convenience and ability to be applied to rounded surfaces.
The Best Solar Panels are either thin-film or multi-junction cells. The thin film can be used in flexible solar panels and have the most promise for growth in the short term future. Multi-junction cells increase their complexity in order to deliver more efficiency per square foot.
It is best to think in terms of kilowatt per dollar. If space is not an issue, then using more solar cells that are cheap are probably the best option. There are only a few instances where space is at an absolute premium.
