It is. There is no single comfortable temperature, it's a range. The first step is when electricity is cheap, cool the house to the low end of the range.
The next step is to cool a tank of water. People already have a hot water tank, it doesn't seem like much of an engineering or cost challenge to have a cold water tank, and using that to cool air.
A further step is to increase the thermal mass of the house, which means it will take longer to heat up. Thermal mass can be simply adding a big pile of rocks in the basement and blowing air through it.
In the summer, even if you cool your house down to 60F, it'll be back to 70F in a couple hours max. Electricity rates from renewable overproduction do not vary on the timescale of hours. It's not a solution without new equipment to "store" the hot or cold that you produce when electricity is cheap.
(Besides, I grew up in Arizona, and was comfortable up to 78 or so.)
This isn't as simple as you make it sound. You can't just cool your house once when electricity is cheap and then have it stay cool all day. Keeping your house at a different temperature than outside is a constant, active process.
There are industrial systems that "store" cold by making large blocks of ice when electricity is cheap, and then using that ice as part of the HVAC system to cool the building throughout the day. This could be adapted to home use, but I have no idea the relative cost of the machinery vs electricity savings.