What is the rate of consumed electricity during day vs night

There is a tip by the bird that says that there is less electricity consumed during night in the city, so the player should lower the budget of the electricity production during night.

Is there a way to determine the exact rate of the consumed electricity during night?

The electricity info panel tells you how much electricity is being used at a given moment, and how much you're producing. During the night cycle, open the panel and monitor how much power is being used. By comparing how much is being used at night, vs how much is produced you can decide how to affect the budget.