Sunrun and Tesla said more than 140,000 home batteries sent a record 580 megawatts into California’s grid on Sept. 9.

  • More than 140,000 household batteries discharged for three evening hours on Sept. 9, peaking above 580 megawatts—enough, the companies said, to cover every home in Sacramento County at peak. 
  • About 110,000 Tesla Powerwalls supplied 517 megawatts; Sunrun owns or runs 55% of those units. 
  • Sunrun CEO Mary Powell said the home-battery network now rivals many traditional backup plants.


Sunrun (RUN) and Tesla (TSLA) said on Monday that more than 140,000 household batteries sent power into California’s grid on the evening of Sept. 9, when a heat wave lifted demand and wholesale prices.

The companies reported a peak of more than 580 megawatts over a three-hour window and described the coordinated discharge as the biggest residential virtual-power-plant event they have recorded.

State officials and utilities asked the companies to tap customer batteries for three hours so the grid had extra supply and prices could ease. About 110,000 Tesla Powerwall batteries supplied 517 megawatts. Sunrun owns or runs 55% of those units. Sunrun also used more than 30,000 batteries from other makers, adding 63 megawatts.

Tesla rose about 2.4% on Monday to near $373 amid a broader market rally. Sunrun gained about 4% to about $8.87.

A Second Night In Southern California

The next evening, Southern California Edison asked for another three-hour release. The companies said they delivered more than 140 megawatts. If both nights had overlapped, they estimated more than 720 megawatts.

Sunrun CEO Mary Powell said the home-battery network now rivals many traditional backup plants and can lower costs even for people who never bought a battery.

Other News Impacting The Stocks

On Monday, the Czech Republic provisionally cleared Tesla’s supervised Full Self-Driving software, the seventh European Union country to do so. Tesla said a local rollout would start soon. Drivers must still stay alert; the system is not fully self-driving.

Goldman Sachs also cut its Sunrun price target to $13 from $15 and kept a ‘Buy’ rating. The fresh price target still implies a potential upside of about 52% from the stock’s last close.

How Did Retail Traders React?

On Stocktwits, retail sentiment around TSLA was extremely bearish at the time of writing, while sentiment around RUN stayed at bearish levels.

TSLA stock has fallen 17% this year, while RUN has lost 52%. 

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