Update: To see solar (and all other supply sources) on the California grid in real time, just go to this CAISO page.

Solar 1 GTM.png
Source: Greentech Media

California already has more mid-day solar power than it knows what to do with. The above graph, published yesterday in an excellent article in Greentech Media, shows the hour by hour source distribution from the California Independent System Operator (CAISO) for March 26th. As you can see, the biggest chunk (natural gas – here called ‘imports’) takes a dive mid-day because there’s so much solar from 9am to 3pm.

This next graph shows what’s called ‘curtailment’ for that same day. Curtailment is when CAISO dials back the amount they’re taking from a source because the grid simply can’t handle it. For reasons to do with contracts and opaque energy-grid politics, only renewables (wind and solar, but mostly solar) get curtailed. On March 26th, according to GTM’s article, about eight percent of solar capacity ended up being curtailed, or unused.

Solar 2 GTM.png
Source: Greentech  Media

This wastage is only going to get worse, as more solar and wind capacity get installed every day in California. We’re already selling as much of it as they can to Arizona, which is a new phenomenon. And it’s already changing the grid’s price curves in the West – at some points during the day, local marginal energy prices even go negative.

What to make of this?

  1. We really want big batteries to suck up all that mid-day juice so we don’t need to use so much fossil fuel at night.
  2. We really want variable time-of-day pricing for most customers to encourage demand to shift to when renewable energy is in oversupply.
  3. We really need better visibility into the economics and politics of California’s energy grid. Per this LA Times article, the people running the show are making terrible decisions, investing in just the wrong kind of overcapacity.
  4. In the meantime, use as much of your power on sunny days mid day as possible!

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