A Voltage Transformer is a device that transfers electric energy from one alternating-current circuit to one or more other circuits, either increasing (stepping up) or reducing (stepping down) the voltage.
How they work
The transformer design works by defining the voltages at each stage of the AC circuit. This includes the inverter's output voltage, the output voltage from the AC panel (if applicable), and the interconnection voltage. Then, whenever there are changes in the voltages (defined by the user), a transformer will be added. Note that you do not directly add transformers to the design.
The output voltage of the inverter defines the AC Home Run (A) voltage. If the output voltage of the AC Panel is different, as defined in the “Panel Transformer” (C) drop-down menu, then HelioScope will include transformers at the AC Panels (Primary Side of the transformer is the connection tied to the facility/utility grid). Similarly, if the grid voltage at AC Interconnection (D) is different from the voltage in range C, then an additional transformer will be included at the PCC.
How to configure them in HelioScope
For more control over the design of an AC system, HelioScope can configure transformers. Please follow these steps:
- In your Design, please go to the Electrical Tab.
- Check the "Configure Transformers" checkbox at the bottom of the AC electrical menu to open the Transformer section.
- Make sure you have AC panels enabled in AC wiring settings (transformers will be placed at the AC Panel, which determines where the voltage will be stepped up or down)
- Set the inverter output voltage in the "Inverter Voltage" field. Note: Depending on the Inverter Selected, this might be pre-defined by the manufacturer. If not user has to define the Inverter Voltage Issues Selecting Inverter Output?
- Set the transformer output voltage in the "Panel Transformers" drop-down. Note: How to determine if a Panel Transformer is needed? Depending on the Inverter used for the project, an AC Panel with a second Transformer might be needed to step down the voltage between the Interconnect and the Inverter.
- Set the grid interconnection voltage by clicking the AC Interconnect Voltage drop-down. Note: if the grid voltage is set, you can change it by clicking the "update" link. *transformers displayed on Single-Line Diagram for explanation purposes, not currently shown on HelioScope Single-Line Diagram
Efficiency and yield impact
Transformers will change the operating voltage of the system, and therefore the wiring losses. Higher operating voltages lead to lower operating current - and therefore, lower, though the transformer efficiency is not currently calculated in HelioScope.