ISO-New England, the folks who run the six-state power grid, estimate that there are 4,000 MW of “behind-the-meter” solar (i.e., rooftop, although some of that is ground-mounted) in the region. That’s a little more than three times the output of Seabrook Station nuke plant, although of course solar is intermittent so Seabrook’s annual production is much more.
They’ve added a tweak to their online system-watching tool, showing real-time estimated BTM solar. Right now (a sunny Wednesday at 3 p.m.) it makes a big difference. Here’s the chart without BTM – yellow is total production, blue is forecast:
… and here it is with BTM:
By the way, if you fiddle with the tool you’ll see there’s a setting called “Pump Load” – that, I found out after asking, is the amount of energy used to pump water uphill as part of the pumped-hydro storage system. It’s “charging the battery”, if you will.
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I’m still a little annoyed that my rooftop solar hot water heating isn’t recognized as it’s value in offsetting either gas, oil or electric energy. The difficulty of accounting for this is about impossible. In the grand scheme of accounting it doesn’t really matter since in our state of NH, domestic hot water use is so tiny. I only know of a couple of other systems. Still, after 31 years, the total offset to my power bill has been worthwhile. Even in those tough months of January and February I still have all the hot water I need. The backup electric elements in my 120 gallon make the system completely transparent to us.