Solar Module,1A 4.4-6.5V input 4.2V output 18650 LiPo Li-ion Lithium Battery Charger MPPT Solar Controller Module(without Pin), Battery Charging Units

Works well

Does the job well and cheaply

OK

This board uses the CN3163 chip which yes, is lithium battery controller optimised for use with solar panels. It does not, however, do any maximum power point tracking (MPPT) despite that being mentioned in the product title.That being said, it’s pretty much plug and play. If you have a project that requires a battery to be charged from a solar panel and you’re not bothered about maximising power output from the panels, then this will do the trick. If you need MPPT, then it’s probably best to look elsewhere.

Smaller than you think so it's difficult to solder. Never got it to fully function but that might be a limitation of my battery. Better off buying a fully functioning commercial unit.