Primary applications for energy storage include Peak shaving and backup power. In California, the highest peak demand occurs weekdays between 1 and 6pm. In a PV + Storage solution, batteries are configured to discharge roughly 45% of capacity each afternoon to shave the most expensive power off the power bill. The usable life of Lithium Ferrous Phosphate batteries is 15 years, equivalent to 5,475 charge cycles. The greater the level of daily discharge, the fewer charge cycles over the life of the battery array. Cold Storage facilities, Hospitals and Data Centers have clear requirements for energy storage, which can often make the difference between a complete shutdown of the facility and maintaining operations until grid-supplied power is restored. A commercial PV system with energy storage accelerates PV system returns and enables off grid capability.
In PV + Storage systems, batteries are charged each day by PV modules tasked with supplying peak power to the facility and at the same time, charging banks of batteries PV + Storage systems use what are referred to as Island Compatible inverters. The primary function of both PV-only and in the case of island compatible inverters for PV + Storage, the inverter converts DC energy generated by PV on the roof to AC power supplied to the utility meter. In PV-only systems, when the grid goes down, the PV system and conventional grid-tied inverter shut down also. This is to prevent the PV system from back-feeding the grid and causing an unsafe condition for service personnel trying to restore power. Alternatively, island compatible inverters used in conjunction with energy storage feature an automated transfer switch activated within milliseconds of the grid going down. The transfer switch prevents back-feeding the grid. When the grid goes down, island compatible PV+ Storage systems operate in a closed loop between the PV modules, the batteries and your facility. If there is not enough energy / battery storage capacity to provide backup power for the entire facility in real-time, the batteries are configured to supply mission critical circuits in the building instead. PV + Storage systems run in a closed loop as standalone power generation systems, backed up in most cases by diesel generators. Should the PV array not be able to keep up with both the battery charge requirement and facility demand, the generators charge the battery array and provide power directly to the facility.
Harmonizing energy storage capacity, discharge settings, load requirements and solar production determines the overall size and capability of PV + Storage systems. Contact us today for more information on how energy storage can reduce operations spend and provide back up power for your facility.