I'm thinking about using a solar panel to extend the life of an IoT device. However, I'm questioning if this will give me good results or if it will only be an expense that wouldn't give any benefits.
I'm thinking about using eight 3.7V 2600mAh 18650 Li-Ion batteries in parallel connected to a solar power manager circuit (this one, with MPPT) that provides up to 900mA to all batteries (112.5mA to each). Given that the Charging Factor (CF) would be very small (112.5/2600 = 0.04C), could it be harmful to the batteries? Maybe it reduces the number of cycles, thus their life span? Or perhaps it has even other negative implications that I'm not seeing?..
Also, I notice that many IoT devices that use both batteries and Solar Panels to power up their circuits usually use less batteries (e.g. one or two ~2000mAh cells only). Is it for an expensive reason? Sparing 2 or 3 batteries for example is really that money-saving? Or maybe they do it to keep the CF higher? if so, why is it necessary?
Thank you in advance from a rookie hardware developer.