In the UK we've had off peak power overnight for decades. My current one is something like 1/3rd of the price of daytime power between 2300 and 0700.

However this is somewhat old fashioned, the most modern tarrifs vary on a 30 minute window, with prices set a day ahead. If there's a lot of solar and little demand on say a sunny sunday afternoon or windy february nighttime, then the prices may even go negative.

You want your consumption to be tied into there. You can do this with batteries -- for example on Tuesday I used 34kWh, 24kWh overnight (mainly to charge the car) and 10kWh in the day. If I had a battery I could have charged that battery overnight and saved a couple of quid, or about £600 a year (depends on what my daytime usage is)

However with a 30kWh battery I could have charged it on Sunday afternoon and been paid for that, and not used any power on Monday, Tuesday or Wednesday for the house. But then the agile rate last night was 25p/kWh. I did look at getting a battery and inverter installed but it wasn't cheap.

On top of that you've got self generation. I have very little solar generation, but in theory I reckon I could have 8kWp on the roof -- I'd want to charge the car (and house battery, and any heatpump or ac) when the sun was shining then, which would be even cheaper than charging at night. Home Assistant will do that, but it feels a little fragile with my car charger (if the HA dies, the charger won't start, and then I can't go anywhere. It's not a great charger)