I don't think you were following what I was saying in my previous post. Yes, you can make this charge up a powerbank, and yes, you can use it to power a remote weather station. However, one designed for one application may not be well suited to supply the other.
To achieve longer charging, yes, add in more series cells. More current, go parallel. Inefficiency will come when you reach peak charge on the battery in 4hrs, but then it taking 4 weeks to deplete the battery.