The Challenge

A Napa-based full-service energy contractor was tasked with helping a renowned winery in the Russian River Valley reduce high utility bills, particularly demand charges that peaked at $22 per kW under PG&E’s B-10 rate schedule. While the winery had already invested in an expansive rooftop solar system, spanning four buildings and featuring 2,284 panels, the site’s remote location presented a major challenge: PG&E substation constraints capped the combined export capacity of solar and battery systems at 980 kW AC.

To stay within these utility-imposed limits while maximizing the value of clean on-site generation, the contractor partnered with Energy Toolbase to implement a solar-plus-storage solution that combined Tier 1 energy storage hardware with intelligent control software. The goal was to dynamically control energy dispatch, slash demand charges, reduce electricity bills, and optimize time-of-use (TOU) savings, all while staying within the export cap. The system was also designed to maximize energy production for powering cold storage, wine-making equipment, bottling lines, compressors, and other energy-intensive equipment.

The Solution

The contractor collaborated with Energy Toolbase to deploy an energy storage system (ESS) integrated with ETB Controller with Acumen AI™, which utilizes dynamic economic dispatch to perform demand charge management based on real-time site conditions and utility signals. As a certified BYD reseller, Energy Toolbase oversaw the seamless procurement, commissioning, and deployment of three 120 kW / 266 kWh BYD CHESS units, totaling a system size of 360 kW / 798 kWh.

Due to the PG&E substation export cap, the contractor implemented a limited export control scheme using SEL 751 relays and inline contactors managed by ETB Controller. This manages battery dispatches to support on-site loads while ensuring the system remains within the export threshold. The batteries are only permitted to export when additional headroom exists, ensuring compliance without sacrificing performance while maximizing system performance. Thanks to the close coordination between the contractor and Energy Toolbase, the winery is now fully leveraging its solar and energy storage investment to achieve its economic and environmental goals.