Many years ago my first retail experience was with a (now defunct) big box catalog showroom we'll call 'Mervis Searchendise'.
All our registers had an 'emergency power outage kit' so we could keep ringing orders if the power went out. It contained manual register forms, pens, a tax table to figure out sales tax, and a calculator.
One day the power did go out, and except for the feeble emergency lights, it was pitch black because as a big box, there were no windows other than the front entrance and exit doors.
All the department cashiers broke out their emergency kits, only to find that ALL THE CALCULATORS WERE SOLAR POWERED!!! Apparently HQ did this so we wouldn't have to concern ourselves with dead batteries.
As I worked in the department that carried calculators, we had a sudden rush of cashiers frantic for our display case of non-solar models. Luckily when the lights came back on we were able to get all the displays back.
Needless to say, we never used the emergency kits again.