Solar Photovoltaic Best Practices and Balance of System Lessons Learned

Southern California Edison’s (SCE) discussion focuses on lessons learned and best practices developed through installation of more than 15 utility-scale solar photovoltaic (PV) projects. SCE’s Solar Photovoltaic Program (SPVP) develops solar PV projects on commercial rooftops (along with a small number of ground mounted projects) throughout its service territory.  During installation of its first 15 projects, SCE has made significant changes to its installation practices, balance of system design to allow for increased ease of project operability and maintainability, and has identified challenges associated with installation of rooftop PV projects.

SCE shares best installation practices such as designing rooftop raceways from conduit to cable tray to allow for natural expansion as the roof heats and cools, and allow for easier maintenance of wiring, as well as changing from aluminum to copper wiring.  Redesign of interconnection architecture allowed cost savings by reducing the number of transformers.  Additionally, SCE will share design improvements made directly with vendors to increase safety and improve ease of system maintenance including: adding windows in combiner box doors; switching from spring clip fuses to bolted fuses; and rearranging cable access in the combiner box.  SCE will also share challenges with installing rooftop PV systems including: securing roof leases with unsure owners and tenants; structural soundness of existing buildings and roof membrane issues such as wrinkles; ponding; and dangerous roof hatch access.

SCE’s best practices and lessons learned provide information for companies beginning a solar PV program that can be applied to gain installation efficiencies, improve operability, and reduce costs.