Net metering compensates solar customers for the power they contribute to the grid — but if they route the electrons through a battery, they’re out of luck.
Utilities understandably don’t want to pay net-metering rates for batteries charged by grid power. So far, that means solar generation stored in batteries for later use doesn’t earn net metering dollars either. That could change, once the California Public Utilities Commission responds to a petition that, unusually, drew support from both the solar industry and utilities.
“If I’m not charging from your electricity, if I’m charging only from a solar source, the battery is basically an accessory to the solar system,” said Joshua Weiner, who worked on the concept as president of design engineering firm SepiSolar, which specializes in solar plus storage. “All the policies in place support this. […] Somebody just needs to say that this is allowed.”
If certifiably solar-powered batteries can get paid, that could unleash a market signal with sweeping ramifications for solar customers and utilities trying to balance a highly renewable grid.
California’s shift to new time-of-use rates lowers the value of solar at midday, when it floods the wires, and increases the price of evening power. That means reduced payback for traditional solar customers who can only export when the sun shines and then have to buy power at night.
Those who pair solar panels with batteries, though, could store midday generation and sell it to the grid at the peak time-of-use rates, if allowed. That personal profit addresses a systemic challenge: the dreaded “duck curve.”
Solar customers would make more money by exporting just when utilities are scrambling to fulfill the steep ramps required in the evening, when solar generation drops off and electrical demand spikes.