My grid is almost never down and its nuclear made electricity is cheap, especially at night and on weekends. My neighborhood cheers and has a party when the grid is rarely down. Only 2 houses in 100 have solar panels on their roof. A few traffic lights and huge signs have a solar panel and battery.

 

It could be related to a so called "ripple control": frequencies from 160Hz to 1050Hz are being added to the mains to control some loads in Peak and Off-peak periods. This is done to regulate the load in the network and some equipment reacts on those tones changing its load. In Australia it happens around 10pm: some power supplies may start "buzzing" around this time (can be a TV, LED lamp, etc). It lasts for 10-15 minutes, then stops. Depending where you are it may or may not be related to this. Here is a WiKi page about it: https://en.wikipedia.org/wiki/Load_management

 

In my area generators burning propane from the 20 pound tanks run about 5 to six hours per tank. That makes power very expensive. My Gasoline powered generator will run for about 24 hours on about 3 gallons of gasoline, so that is vastly cheaper. I have not yet made the connections to run on natural gas, but the consumption should be quite a bit less than running on propane, and the price for natural gas per unit of energy is much less than propane.
And the grid in my part of town is down long enough to require using the generator several times a year. Except for the first year after purchasing the generator, which there were no outages for almost 18 months immediately after that. Then the outages resumed.
Control of consumer load shedding is done with RF links in my area, not sure how the utilities control their remote devices.. The highly touted new scheme will be "gen5 internet connections". I predict that scheme will be quite hackable.