That post was predicated on them being hooked up . .if you hooked it to some marine batteries or glass mat batteries you could run and inverter and getplenty of energy to run a aquarium tank heater or a light bulb.
jon
The caveat was the amount of winter daylight charging the batteries.
Even in low daylight, however, one could buy a couple batteries and lug one out to provide power & bring the other in to recharge . . .