Commercial Solar + Storage Case Study | The Crossings Church, Costa Mesa, CA
How a high-attendance Southern California church added a Fortress Power eSpire commercial battery storage system to its existing solar array to cut peak demand charges and keep the lights on for thousands of worshippers every week.
Location: Costa Mesa, CA
Clients: The Crossings Church
System Size: 280 kWh
System Components: Fortress Power eSpire 280 | 260.4 kWdc / 212.5 kWac Solar PV Array | Keystone EMS | Keystone Microgrid Controller
Installation Partners: Treepublic
Application: Peak shaving
The Need
A church the size of The Crossings is not a quiet building on Sunday mornings. Multiple worship services run back to back, filling the sanctuary with thousands of attendees across the course of a single day. Throughout the week, the campus stays active with small groups, ministry programs, and community gatherings. Private events fill the calendar on evenings and weekends. At any given time, the facility is running lighting, sound systems, climate control, and all the infrastructure required to host a large, active congregation comfortably and consistently.
That level of sustained activity drives significant energy demand, and in California’s utility environment, the cost of that demand is not just about kilowatt-hours consumed. Peak demand charges, which are based on the highest level of power drawn from the grid during a billing period, can represent a substantial portion of a commercial electricity bill. For a facility that routinely draws heavy loads during Sunday services, those peaks add up fast.
The Crossings had already made a meaningful investment in on-site solar generation. But without battery storage, the benefits of that solar were constrained. The church was generating clean energy, but had no way to store it and deploy it strategically during the high-demand windows that were driving its largest utility costs. Adding a commercial battery energy storage system to the existing array was the logical next step.
The Solution
The Crossings partnered with Treepublic, a California-based clean energy solutions provider, to design and install a Fortress Power eSpire 280 battery storage system alongside the church’s existing solar infrastructure.
One of the defining advantages of this project was its simplicity. Because the eSpire is AC coupled, it was integrated directly with the existing PV system on the 480V AC side, with each system maintaining its own inverter and power conversion system. There was no need to redesign or modify the existing solar array. The eSpire was added cleanly alongside what was already there, minimizing disruption to the church’s operations during installation and allowing the project to move efficiently from design to completion.
Keystone EMS provides the intelligence layer, managing battery dispatch, monitoring system performance, and coordinating the interaction between the solar array and the eSpire in real time. The addition of the Keystone Microgrid Controller takes that a step further, giving the facility the capability to operate as an independent microgrid when needed, adding a layer of resilience that a high-occupancy public gathering space genuinely benefits from.
The system was fully operational by August 2026.
Results
With the eSpire in place, The Crossings now has the ability to store solar energy and deploy it precisely when it is needed most. During Sunday services and other high-attendance events, when the facility’s power draw peaks, the system draws from stored battery energy rather than pulling from the grid, directly reducing the peak demand charges that had been inflating the church’s monthly utility bills.
The AC-coupled configuration means the existing solar array continues to perform exactly as it always has, with the eSpire adding storage capacity without any disruption to existing generation. The church gets the full benefit of its solar investment alongside the added value of intelligent peak shaving, all managed through a centralized platform that gives facility managers clear visibility into system performance.
For a campus that hosts thousands of people every week across worship services, weekday programming, and private events, reliable and cost-efficient power is not an afterthought. It is what allows the ministry to focus on its mission rather than its utility bills.
Smart Storage for High-Demand Facilities
The Crossings project is a strong example of how commercial battery storage can be added to an existing solar investment without starting from scratch. For churches, event venues, schools, and other facilities that see predictable high-demand windows, peak shaving with the Fortress Power eSpire delivers immediate, measurable cost savings alongside improved energy resilience.
The combination of Keystone EMS and the Keystone Microgrid Controller means the system is not just reactive, it is intelligent, giving facility operators the tools to manage energy proactively and keep operations running regardless of what the grid is doing outside.
Ready to explore what a commercial solar + storage system could do for your facility? Start a C&I Project Quote.
