Sunnyvale Runs Its Net-Zero Civic Center on 736 kW of Solar, 330 kWh of Battery and a 1 MW Generator

Sunnyvale, California’s rebuilt civic center runs on a grid-connected microgrid pairing 736 kW of rooftop solar with 330 kWh of battery storage and a 1 MW diesel generator. The system began operation in fall 2025. Designers aimed for the solar to offset 100% of the campus’s annual energy use and reduce peak demand by 73%. The campus, housing city hall, the library, and public safety headquarters, carries both net-zero energy status and LEED Platinum certification.

The microgrid addresses a problem created by the all-electric design. Sunnyvale removed gas from the buildings to meet energy targets. This decision eliminated the fuel-fired equipment a civic campus typically relies on during an outage. Wildfire and earthquake risks made this gap unacceptable for a site housing police dispatch and a library used as a public gathering point.

How the controller decides

The microgrid switches between resources in real time, avoiding generator startup on every outage. During a daylight outage, the controller powers the buildings using the battery and rooftop array. At night, it activates the generator. The emergency operating center maintains its own separate backup, meaning the microgrid does not solely handle city crisis functions.

This sequence of operations is the battery’s primary function. A conventional standby system burns diesel from the first second of any interruption, including brief ones. Sunnyvale’s design prioritizes stored electricity, treating fuel as a last resort.

Why It Matters

Cities electrifying public buildings face the same challenge Sunnyvale encountered. Reach codes and net-zero targets eliminate gas from civic construction, leaving the backup generator as the last gas-burning device. A microgrid controller transforms that generator from a first responder into a resource of last resort. The ratio in this project offers a practical reference. Sunnyvale deployed 330 kWh of storage against 736 kW of solar and a 1 MW generator, covering short daytime interruptions with stored energy and reserving fuel for extended night outages. Any city sizing a similar campus must determine its priority: short daytime interruptions or long night outages, as this decision dictates battery requirements.

The part the project does not answer

Neither the city nor its design team has released data on how long the campus can operate islanded or the microgrid’s cost compared to a standard standby generator. A 330 kWh battery is small relative to a 1 MW generator, meaning the diesel handles the bulk of the load in any prolonged event. The resilience claim hinges on the controller’s swift and accurate decisions, and no public record details the system enduring a multi-hour outage. Marco Alves, an engineer and project manager at PAE, discussed the design process, not operating results. Sunnyvale is not alone in adopting this approach. Houston is planning microgrids across approximately 12 neighborhoods requiring resilient police, fire, and water services.

SmithGroup served as the architect for the campus, with PAE as the engineering and design firm. Hensel Phelps managed construction. PAE guided stakeholders through a Choosing-by-Advantages process to select design options, and the team met Sunnyvale’s reach codes, which exceed California state code.

Critical Perspective

The most telling decision in this project is the one the city made about its emergency operating center. That building keeps its own separate backup rather than depending on the microgrid. Sunnyvale put the function with the least tolerance for failure outside the system it is promoting for resilience. That choice is defensible engineering, and it also sets a limit on how far the microgrid claim reaches.

The headline numbers measure different things than an outage does. Offsetting 100% of annual energy use and cutting peak demand by 73% are accounting results across a year. Neither describes the hour the grid fails. A 330 kWh battery is modest next to a 1 MW generator, so any long interruption still runs on diesel, and the campus has not published how long it holds islanded or what the microgrid cost against a conventional standby system. Until Sunnyvale reports a real multi-hour outage, the resilience case rests on design intent rather than on measured performance.

Sources

• Microgrid Knowledge: California City’s Civic Center Faced Critical Energy Question for its Master Plan. A Microgrid Answered it (Sept. 9, 2026)
• Hensel Phelps: Sunnyvale Civic Center Microgrid project record
• PAE Engineers: Sunnyvale Civic Center project record

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