Willowbrook-Integration to Enable Solar as a Distribution Resource

PROJECT PURPOSE The primary objective of the project was to identify scalable community models to maximize the economic and environmental benefits of solar photovoltaic energy systems for low-income populations and affordable housing facility operators. With Southern California Edison as a key partner and local utility, this resource integration project also evaluated how to further scale and to enable grid flexibility, reliability and greenhouse gas emission reduction that is beneficial to the entire rate base.    The technology innovations noted above were selected based on their potential to align with the policy direction of California targeting the low income multifamily sector.  Emphasis was placed on business models that supported the economic and environmental advancement of low income residents as California Investor Owned Utilities transition all residential customers, including those on affordable discount rates, to time of use (TOU) rates with time differentiation and peak pricing and that benefitted utilities and the larger rate base including balancing solar to avoid distribution upgrades and shave peaks, reducing GHG from the California electric system and managing bulk system capacity through demand response (DR).    Most of the chosen innovations are emerging technologies, which were challenging to deploy due in part to limited product availability, lack of familiarity by permitting authorities and stakeholders, code limitations and compatibility issues.  Still, this resource integration project has garnered heightened attention not only for its energy efficiency and DR benefits but as a realized demonstration of DC distribution and appliances that could be expanded with the provision of automatic transfer switch to offer low income community resiliency as it could provide backup power and a resiliency center during local outages to support critical loads like medical devices and air conditioning.  PROJECT RESULTS EPRI partnered with Linc Housing (Linc), a California-based affordable housing owner, on siting this demonstration project at a 61-unit low-income multifamily property in Compton, California called Mosaic Gardens at Willowbrook (Willowbrook).  EPRI also partnered and received funding from Southern California Edison, the local electrical utility.  In 2020 and 2021, the team successfully deployed and tested the resource integration demonstration comprised of the following technologies:  2 battery cells 60 kW / 2-hour, provided by EnergPort 2 60-kW bifacial solar photovoltaic (PV) arrays, provided by Canadian Solar DC-coupled PV and storage system, with inverter provided CE+T Inverter meeting CA Rule 21 Phase mandates for grid supportive functions A local controller coordinating PV, battery, and inverter, provided by GridScape A level up is the Open Demand Side Resources Integration Platform (OpenDSRIP), developed by EPRI and funded through another CEC grant (EPC 15-075), coordinating overall system controls This project utilizes Virtual Net Energy Metering (VNEM). The production and operation of the PV and battery will be distributed (allocated) across each of the residential unit meters and the Common Building meter The project will include common area lighting and air conditioning DC loads, directly coupled with the battery system.   First, EPRI followed a process that involved working with the technology integrator Gridscape and EPRI technical staff to simulate and fine tune the integrated system within a lab setting at its own facility before deploying the field. The project partners had to delay construction by approximately one year to conduct comprehensive due diligence. Willowbrook is a tax credit financed property with multiple lenders, one of which had had a poor experience with previous solar projects (leaking from roof penetrations).  The second challenge was the prolonged sourcing, testing, permitting, and interconnection processes associated with implementing the emerging technologies of the project scope, especially the direct current (DC) distribution and appliance demonstration elements.    This project was unique in its DC side connection of solar and storage with a single inverter. Getting through the permitting process required a significant amount of work with the County of Los Angeles, the local permitting authority, as it was unfamiliar with a DC side connection.  It was also difficult to obtain local utility SCE approval, but it was enabled by prior work the vendor had completed with PG&E on a software based monitoring solution for non-export Rule 21` interconnect.  On the DC demonstration, several iterations of plans were submitted, and parts were not readily stocked or available as market demand was low.  For example, DC lighting in this project used low voltage, low power controls that are being used and accepted elsewhere with no UL listing.  LA County in this case forced the project team to obtain a UL field evaluation for low voltage lighting controls.  Simply the cost and scope of getting an NRTL to provide a field evaluation would prevent most customers from considering this route.   The systems were ultimately installed in two phases by Staten Solar: the solar + storage followed by the DC demonstration and monitoring and verification instrumentation.  During this time, the Covid-19 virus emerged and ensuing global pandemic resulted in elevated precautionary measures to avoid transmission and exposure among crews and property occupants and staff, supply chain issues for some of the components and related setbacks to on-site work and supervision. To address these challenges, the project team took time, hired a dedicated construction manager, addressed issues in recurring weekly meetings, followed Covid safety protocol and engaged external stakeholders. Furthermore, a technical advisory committee (TAC) was formed and met two times throughout the duration of the project, during which some of these issues were addressed.