I actually use one of the flexible panels in our very small popup to charge a small U1 style battery. The only thing I dislike about the flexible ones is that they surface seems to be more prone to scratching...which will reduce efficiency. If I had the space to go for a full size regular glass panel, I probably would have. Even with a 50W panel and this battery, its more than enough to charge phones, power lights, water pump, and any other USB charging that we need for our 2-3 night stays. As said, if you can afford the more expensive panels and controllers, they will certainly give you more efficiency per cubic foot than the cheaper systems. The return on expense for more panels, I think..., is higher than getting more efficient gear.