Should we get excited about California’s latest virtual power plant?

PG&E, Google, and the nonprofit Rewiring America have launched a program called SHARE that pays Northern California homeowners to let the utility tap their batteries and smart devices to help the grid. PG&E will recruit more than 20,000 customers who already have Sunrun or Tesla solar-charged batteries or Renew Home smart thermostats, offering an as-yet-unspecified reward for letting the utility control those devices at times of grid stress. Separately, Google and Rewiring America will offer discounts on Carrier's new battery-equipped heating and cooling units — $5,000 off, or $10,000 for the first 25 customers who sign up. Google is covering the cost, starting with about $14 million for the first phase, so the program won't add charges to PG&E bills.

The bigger context: PG&E has launched similar pilot programs before and canceled them, and critics, including clean-energy investor Jigar Shah, argue California utilities have failed to build lasting networks out of the huge number of home batteries already installed in the state, unlike utilities in Massachusetts, Utah, and Vermont. There's also a dispute over whether SHARE is really meant to offset costs tied to a large Google computing facility planned in San Jose, something both companies deny.

For homeowners, this mainly matters if you already have or are considering a home battery, a Tesla or Sunrun system, a smart thermostat, or a new HVAC unit — those are the devices eligible for enrollment or discounts. Programs like this vary by utility and state, so it's worth checking what your own utility offers.