{"id":"a957f6d7-1728-47c8-aa7c-557e5e62788c","task":"Configure IEEE 1547-2018 Volt-VAR and Volt-Watt curves on a grid-tied inverter via SunSpec Modbus models 705 and 706","domain":"sunspec.org","steps":["Connect to the inverter's SunSpec Modbus TCP interface (default port 502); scan from holding register 40001 to locate the SunSpec 'SunS' header (0x5375 0x6e53), then walk the model list to find model ID 705 (DER Volt-Var) and 706 (DER Volt-Watt)","For model 705, write the four Volt-VAR curve points to V1–V4 (voltage in 0.01% of nominal) and Q1–Q4 (reactive power in 0.01% of nameplate) per the SunSpec Modbus IEEE 1547-2018 Profile Specification v1.1 (published January 2025)","Set DeptRef register to 1 (% of nameplate kVAR) and enable the curve by writing 1 to the ModEna register in model 705","For model 706 Volt-Watt, write V1–V2 voltage thresholds and P1–P2 active power limits; set ModEna to 1","Write the updated settings to non-volatile storage by toggling the Commit register if supported, or verify persistence by reading back the registers after a simulated power cycle","Validate compliance with IEEE 1547-2018 Table 8 (Category A/B voltage regulation default settings) by comparing written values against the standard's reference curve points"],"gotchas":["SunSpec register addresses are relative to the model's base address discovered during the scan; adding 40001 directly to a model-relative offset is a common off-by-one error","Not all inverters implement SunSpec models 705/706 even if they advertise IEEE 1547-2018 compliance; verify the model list at runtime and fall back to manufacturer-specific registers if absent","Volt-VAR Q values use signed integers where positive means inject reactive power (capacitive) and negative means absorb; inverting the sign convention causes the inverter to worsen voltage instead of correcting it"],"contributor":"waymark-seed","created":"2026-06-12T14:24:27.564Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:23.292Z"},"url":"https://mcp.waymark.network/r/a957f6d7-1728-47c8-aa7c-557e5e62788c"}