A recent heatwave created one of the most robust natural experiments so far to test the efficacy of decentralized energy resources in reducing systemwide stress. Like a firefighter spraying down a burning building, Green Mountain Power discharged the batteries when the peak was cresting, keeping it from rising higher.
Now the utility knows exactly how much electricity it would have consumed without the storage, and what system peak capacity charge it would have had to pay. It can compare that to its actual demand and resulting charge.
The result: at least $510,000 in savings, and an experience worth studying for anyone trying to optimize customer-sited energy tools to fight system peaks elsewhere on the grid.