San Jose bus depot solar and battery microgrid, more than 3 years in the making
Santa Clara Valley Transportation Authority, called VTA, broke ground on September 26, 2025, on a San Jose bus depot solar and battery microgrid at the Cerone Bus Division in San Jose. VTA, Proterra Powered and Energy, and Scale Microgrid Solutions first announced the project in January 2022. A microgrid is a small power system that can run a site on its own solar power and stored battery energy even when the main electricity grid goes down. For an agency switching to electric buses, that means charging can continue through a power outage.
The project changed considerably over the more than 3 years between the 2 dates. The planned solar capacity fell from about 1.5 megawatts to 500 kilowatts, a drop to roughly a third of the original size, while the number of electric buses the depot is meant to charge grew from 34 to 35. The original target date for the system to come online, late 2023, slipped to 2026, nearly a 2 year delay.
Planned in 2022 figure from source 2. Built starting 2025 figure from sources 3 and 4.
Show the numbers
| Planned in 2022 | 1.5 |
| Built starting 2025 | 0.5 |
How VTA is charging its electric buses at the finished depot
The built system pairs 500 kilowatts of solar panels with a battery that stores 4 megawatt hours of usable energy and can put out 1 megawatt at once, according to Scale Microgrids, which built it. 2 fleet chargers rated at 1.5 megawatts each, 3 megawatts total, plug directly into the buses. That charger capacity is separate from a 3 megawatt grid upgrade Pacific Gas and Electric is installing at the same site so it can deliver that much power, according to a blog post VTA published. The 2 numbers describe 2 different pieces of hardware that happen to share a figure, not the same 3 megawatts counted twice.
This is the kind of collaboration that moves clean energy forward. By supporting EV charging infrastructure, we're helping VTA build flexibility and resiliency into their operations.
Jeremy Howard, senior regional manager at Pacific Gas and Electric. Source 4.
Solar, battery peak output and charger capacity from source 3, also stated independently in source 4. Pacific Gas and Electric grid upgrade from source 1, also stated in source 4.
Show the numbers
| Solar panels | 0.5 |
| Battery peak output | 1 |
| Electric bus chargers | 3 |
| Pacific Gas and Electric grid upgrade | 3 |
What the microgrid is expected to save
Scale Microgrids states the system cuts electricity costs for VTA by 48%, cuts carbon dioxide emissions by 61%, and can keep buses charging for more than 4 hours during a grid outage. VTA, in a separate blog post, puts the saving at over a third of electricity costs and 1.2 million dollars a year.
Expanding our zero emission bus fleet reflects my priority to modernize VTA's operations while improving air quality and reliability for the communities we serve.
Sergio Lopez, VTA board chair and mayor of Campbell, California. Source 1.
A pattern other transit agencies are watching
The nearly 3 year gap between the 2022 numbers and what got built shows how much a transit infrastructure plan can shift before a shovel goes in the ground. The battery and charger specifications held steady the whole time, while the solar plan shrank and the schedule slipped. For other agencies planning a similar bus depot solar and battery microgrid, the finished VTA project is a record of what changed and what did not, not an announcement of what was promised.