I think "Solar Generator" is a deceptive and dishonest marketing term when applied to a battery pack.
B
attery packs are storage devices, which are charged and discharged, but
don't generate electricity.
Refrigerators are also storage devices. One can put food in a fridge (at least until it is full), one can take food out of a fridge (at least until it is empty), but,
the fridge doesn't generate food.
There are many ways to generate electricity. For example, one could use gasoline, diesel fuel, wind, water, humans, and/or the sun. It can be quite useful to store this energy for use at another time. Perhaps for when the wind isn't blowing, the sun isn't shining, when one wants the quiet of a non-running engine, or simply doesn't want to pedal at the moment.
Batteries can be used to store energy for those times. "Battery Packs" have a battery, or batteries, for storage.
Solar panels covert solar energy in to electrical energy. Battery packs don't convert solar energy in to electrical energy, but, rather, they can store electrical energy from gas generators, diesel generators, hydro, humans, and from solar panels.
Please don't be fooled by the marketing term "Solar Generator". Please don't trust any company that uses the marketing term "Solar Generator" on anything that isn't (only) a solar panel.
So just how do we get electricity from water? Actually, hydroelectric and coal-fired power plants produce electricity in a similar way. In both cases a power source is used to turn a propeller-like piece called a turbine.
www.usgs.gov
www.usgs.gov