Reference · built on requestOperator by FibricEnergy & demand

Export Limit

Watches inverter output, site load, and the utility's export limit or price signal, and proposes an active-power cap on the solar inverters.

Request accessPricing ↗

About

An interconnection agreement may cap what a site exports, and a low or negative wholesale price can make export worth less than nothing. Inverters that speak SunSpec expose a limit for this: WMaxLimPct in the Immediate Controls model, with a window, a timeout, and a ramp, or WMaxLimPct and WSet in the DER AC Controls model.

Export Limit reads inverter output and state over Modbus TCP, net site load and export from the service-entrance meter, and the hourly demand and price series EIA publishes for your balancing authority. When export approaches the agreed limit, or a price threshold you set is crossed, it proposes a cap on the inverters with a reversion timeout so the limit expires on its own. You approve the cap, and the receipt keeps the readings and the register values written.

This is a reference listing. It documents what Fibric would read from Export Limit and what it could propose, based on the vendor's published interfaces. Fibric builds it under a managed deployment when you request it; selecting it here installs nothing.

Inputs

  • Inverter active power, operating state, and events from SunSpec model 103 or 701 over Modbus TCP, including THROTTLED and PV_CLIPPED
  • Total energy injected and absorbed, TotWhInj and TotWhAbs, per inverter, as the day's export record
  • Net kW, direction of flow, and kWh at the service entrance from the site meter over Modbus TCP
  • The limit as the inverter reports it: WMaxLimPct, WMaxLim_Ena, and the reversion timeout WMaxLimPct_RvrtTms
  • Hourly demand and the day-ahead and real-time price series for your balancing authority from EIA
  • Limits held in a monitoring platform where one exists: SMA GridControl schedules, Enphase VPP events, or SolarEdge live power flow

Proposed actions

  • Target capability: propose writing WMaxLimPct with WMaxLim_Ena, a ramp time, and a reversion timeout on each inverter through the Modbus connector
  • Target capability: propose an ExportLimit or GenerationLimit schedule command on an SMA plant with a start time and duration
  • Target capability: propose a VPP event through the Enphase API that curtails PV for the priced hours
  • Target capability: propose releasing the cap early when site load rises and export falls below the limit
  • Target capability: propose a check when the meter still shows export above the limit after a cap was applied

Proposed actions are target capabilities. Every action runs propose-first and needs a validated deployment and the appropriate permissions.

What you can build

  • Hold export under the interconnection limit

    Read inverter output over Modbus TCP and net flow at the meter, and get a proposed WMaxLimPct with a timeout whenever midday export nears the agreed figure. Approve it, and the cap expires on its own.

    With Modbus TCP, Grid Demand & Prices

  • Curtail when the hourly price goes negative

    Watch EIA's real-time price series for your balancing authority and propose an ExportLimit schedule on the SMA plant for the hours priced below your threshold.

    With SMA API, Grid Demand & Prices, Modbus TCP

  • Prove the cap held

    After a cap, compare the meter's export with each inverter's TotWhInj and the SolarEdge site power flow, and propose a check when they disagree.

    With SolarEdge Monitoring API, Modbus TCP

Requirements

  • Inverters exposing SunSpec models over Modbus TCP, or an SMA, Enphase, or SolarEdge monitoring connector for the plant
  • A Modbus TCP connector polling the service-entrance meter with direction of flow
  • The export limit from your interconnection agreement, and the price threshold you want honored, in writing
  • The EIA grid signal with your balancing authority named, when price is one of the triggers
Authentication
Writes inverter registers only through the Modbus connector's per-device allow-list as approved proposals, uses the OAuth 2.0 credentials your SMA or Enphase connector holds, and reads EIA with its free API key.

Limits

  • SolarEdge and Fronius interfaces are read-only here. A cap on those plants needs the inverter's Modbus registers or the installer's tool.
  • EIA series are hourly and published after the fact. They inform a cap; they do not replace a real-time price feed from your ISO.
  • A cap written to the inverter is only as good as its SunSpec implementation. Some ignore the ramp or the timeout.
  • It caps active power. It does not disconnect an inverter, change protection settings, or touch reactive power.

Access and pricing

Reference listing. Fibric builds the operator under a managed deployment when you request it. Your quote covers the build, capabilities, usage, and support.

Request Export Limit ↗

Questions and answers

What do you approve before a cap is written?
Each cap: the inverters it covers, the WMaxLimPct value, the ramp and reversion timeout, and the meter and price readings behind it. You can change the value or the duration. You can also approve a standing rule for the interconnection limit alone.
What record does a cap leave?
A receipt with the readings at the time, the registers or schedule command written, each inverter's acknowledgement, the timeout set, who approved it, and the write that clears it. Export energy before and after is recorded from the meter.
Can it shut the array down?
It cannot. It writes an active-power percentage with a timeout and never sets Conn to DISCONNECT, changes protection settings, or alters reactive power. A cap left in place past its timeout reverts inside the inverter itself.
Ask about Export Limit

Ask about the capabilities and requirements in this listing.

For project-specific requirements, contact Fibric.

This operator is developed, published, and supported by Fibric. Third-party names and logos identify the systems an integration connects to; they are the property of their respective owners, who are not affiliated with Fibric and do not sponsor or endorse this listing. Trademark policy