[spiderfarmer]

> The batteries are [used] during the peak period, which is in the evening, typically around seven o’clock, producing as much as 40 percent of the peak capacity requirements.

In most countries the peak period is a 4-5 hour window.

[rented_mule]

Yep. PG&E is the electric company for most of Northern California. Their "time of use" plans typically specify 4 PM to 9 PM as the peak period.