
Modbus TCP
SunSpec Model 120 — Nameplate
SunSpec
Overview
SunSpec Model 120, titled Nameplate, is a vendor-neutral information model defined by the SunSpec Alliance for Distributed Energy Resources. The template reads device identity and static nameplate ratings via Modbus TCP, covering continuous active power (wrtg), apparent power (vartg), per-quadrant reactive power limits (varrtgq1 to varrtgq4), current rating (artg), per-quadrant power factor (pfrtgq1 to pfrtgq4), energy capacity (whrtg), charge capacity (ahrrtg), and maximum charge and discharge rates (maxcharte, maxdischarte). Every measured value is paired with a SunSpec scale factor register. Knowing these nameplate figures lets you cross-check live readings against design limits across any compliant inverter or storage device.
Use cases
- Verify that the active power rating reported by wrtg matches the device datasheet after initial commissioning.
- Compare per-quadrant reactive power limits (varrtgq1 to varrtgq4) against grid-code requirements at each site.
- Monitor the rated energy capacity (whrtg) of a battery-backed DER to track whether the manufacturer rating is correctly advertised over Modbus.





