| A bimodal system is a PV system that can operate in either utility-interactive or stand-alone mode, and uses battery storage. Bimodal systems are sometimes referred to as battery-based interactive systems. The key component in a bimodal system is the inverter, which draws DC power from the battery system instead of the array. In this case, the array simply acts as a charging source for the battery system.
Bimodal systems operate in a manner similar to UPS and have components similar to those found in UPSs. Under normal conditions bimodal systems operate in interactive mode, serving the on-site loads or sending excess power to the grid while keeping the battery fully charged.However, if the grid becomes de-energized, control circuitry disconnects from the utility and operates the inverter to supply AC power from the battery bank. If the system must be taken off-line for service and maintenance, a manual transfer switch or bypass circuit can isolate the array battery, and inverter from the remainder of the system and directly connect the loads to the utility supply. Bimodal systems are typically used to back up critical loads, but can also be used to manage the energy supply for different times of the day in order to reduce the electric bills. |
