[Power] Charge controller ?

[Mikus Grinbergs]

Rightly or wrongly - my present thinking is that it takes a "charge
controller", placed between the solar panel(s) and the battery, to keep
a solar-powered charging system happy.

Assuming the intent is to have a 12 V battery supplying power to two XOs
at a time, any recommendations on "charge controller" __specifications__
for that kind of a setup ?

Thanks,  mikus   (hobbyist, U.S.A.)