We stock this MPPT as a more flexible budget option compared to the Genasun. It is not waterproof, and doesn't have quite as good of a warranty, but for $75 it's really handy, especially when you have batteries of multiple voltages for a single bike.
"400 watt maximum power point tracker (MPPT) for your special solar panel needs.
Programmable up to 84V output for higher voltage eBike batteries and with LED display showing both input voltage and current, and output voltage and current, for immediate readout of solar panel performance and charge current into battery pack.
24V-85V battery output (10S to 20S Li) - MAX 15A - current limited
18V-55V Solar Input - MAX 400W or 15 amps, ~0.5W quiescent draw.
No Reverse Polarity Protection on battery output
Not Waterproof, but seems pretty water resistant"
^Above description and pictures are provided by Grin Technologies, the distributor of this product.