When the Mini560 boards arrived, i desoldered the voltage converter from the original PCB.

I sawed out a piece of the pcb, so that the Mini560 board could fit.

Now, the converter could deliver 4A - great, i got more than 20 Watts out of it!

But it seemed to be finicky. The mini560 boards are just buck converters, and they don't have any MPPT - maximum power point tracking. This is a feature needed to get the most power out of solar cells. 

So, i decided that i would build a poor man's version of an MPPT control - just using the Mini560 board.