[M_a_t_t]

So I have these solar panels and charge controller I was going to put on my van for an alt delete, but recently I came to my senses and realized that I don't drive the van enough (<3000 mi a year) to get much of a ROI out of any ecomods.

I am looking at getting an ebike for my commute because it is 2.5 mi each way with minor hills. I would like to use the panels to charge it (almost primarily), but the problem I am finding is that the charge controller only supports 12v, 24v, and 48v batteries. I already have a 12v LifePo4 pack that I can add cells to, but I can't find a decently priced 24v ebike kit. I am not very interested in going straight to 48v because of the cost of the cells + the BMS.

I have found plenty of well priced 36v systems ( like Ecky's) Is it safe to under-volt the motor, but have a 24v motor controller to control it? If I find its not powerful enough could I eventually upgrade to a 48v motor controller and battery and just over-volt the motor? I understand it could vary motor to motor, but for the most part is it safe?

I'm a college student that doesn't get paid much so the initial cost is pretty important. I'm thinking in the $500 total area. Suggestions are welcome.

Thanks, Matt

Links:
Solar panels, I have 2 100W
Charge controller Manual (Trakmax 30L)
Battery Cells