The result is that, if you wind the handle faster, it gets harder to turn, and the battery is charged more quickly.

ECONOMIST: MONITOR

Local utilities here say that, at times, they are already producing more wind power than the electrical grid can handle.

NPR: Young Workers Find Opportunity In Power Industry

As a result, a system using wind and solar has to be built with sufficient system capacity from conventional sources to be handle the system full load without the wind and solar systems.

FORBES: Why Shale Gas is Closing Coal Plants: So Why Do the Hippies Hate Shale?