Nucleo GX Manual

[en] Opportunity Loads can be enabled via the GX device user interface:

[en] Navigate to: Settings → System Setup → Opportunity Loads → Enable

[en] Once enabled, detected devices can be configured as controllable loads, load priorities can be assigned, and device-specific settings become accessible.

[en] Navigate to: Settings → System Setup → Opportunity Loads → Preferences

[en] Pause Opportunity Loads if no AC input is connected

[en] When enabled, Opportunity Loads pauses whenever no AC input source is connected. This is useful for backup systems where only essential loads should remain active during grid outages. When disabled (the default), controlled loads are shed as much as possible on AC input loss to support system stability; after approximately one minute, Opportunity Loads may resume if sufficient surplus is available.

[en] Nominal inverter utilisation limit

[en] Defines the maximum continuous power level the inverter/charger should plan for when serving both base loads and controlled loads. The base load is deducted from this value; Opportunity Loads then enables additional loads up to the remaining headroom. AC-PV is always utilised up to 100% regardless of this setting.

[en] This helps avoid inverter overload, maintains headroom for sudden consumption peaks, and improves stability during fluctuating PV conditions. In grid-tied systems, it does not restrict the inverter's ability to export to the grid.

[en] Example: With an 80% limit on a 6,500 W system, the algorithm plans for a maximum of 5.2 kW. At a 2 kW base load, up to 3.2 kW is available for controlled loads. With an additional 4 kW of AC-PV present, up to 7.2 kW becomes available for Opportunity Loads.

[en] Pause Opportunity Loads when Active SoC limit exceeds 85%

[en] Relevant for ESS systems using BatteryLife. When BatteryLife's active SoC limit reaches 85%, Opportunity Loads pauses to give battery charging priority and improve the likelihood of the battery recovering to a healthy SoC. Operation resumes automatically once the active SoC limit drops below 85%. See the ESS Design and Installation Manual, chapter 6.2, for further information on BatteryLife.

[en] Navigate to: Settings → System Setup → Opportunity Loads

[en] When multiple controllable loads are configured, priorities determine how surplus energy is distributed. Devices are arranged in a priority list (top = highest), adjustable via the up/down buttons in the Opportunity Loads overview.

[en] Priority relative to the battery

[en] Each load is positioned either above or below the battery in the priority list:

[en] Priority-Aware Best Fit

[en] If the available surplus is insufficient for the highest-priority load, the system may temporarily activate a smaller lower-priority load instead. Once enough surplus becomes available for the higher-priority load, the system switches preference back — potentially turning off the lower-priority load. This ensures surplus energy is never left unused while still preferring higher-priority loads whenever conditions allow.

[en] Example: A 3,000 W load has higher priority but only 1,200 W surplus is available. A lower-priority 1,000 W load runs temporarily. When surplus rises to 3,000 W, the system switches to the higher-priority load.

[en] Multiple loads can also run simultaneously when sufficient surplus is available. The GX device continuously rebalances active loads as conditions change.

[en] Navigate to: Settings → System Setup → Opportunity Loads → Battery

[en] Allow additional loads starting at a battery SoC of

[en] Defines the SoC threshold from which lower-priority loads (placed below the battery) may begin using surplus solar energy. Below this threshold, only loads placed above the battery will run; all other available solar is used to charge the battery.

[en] Reserve for battery charging

[en] Two reserve power values can be configured — one at the SoC threshold and one at 100% SoC. Between these two points, the reserved charging power is adjusted gradually, giving the battery higher priority at lower SoC levels and making more surplus available for Opportunity Loads as the SoC rises.

[en] Example: Reserve 2,000 W at 80% SoC, and 100 W at 100% SoC. This maintains healthy charging behaviour, ensures the battery reaches full charge regularly, and maximises solar utilisation at high SoC levels.

[en] If the EVCS was previously connected via the legacy Modbus TCP method, it must first be migrated to the new MQTT integration before use with Opportunity Loads. See EVCS MQTT migration guide for the required firmware and migration guide.

[en] For Opportunity Loads to take control of a charging session, all of the following conditions must be met:

[en] The EVCS has its own built-in surplus charging algorithm that operates independently using metrics from the GX device. Opportunity Loads, by contrast, performs centralised coordination across all configured devices — multiple EVCS units, Shelly loads, and others — preventing independent controllers from competing for the same available energy.

[en] When no GX-controlled algorithm is active (e.g. at night when Opportunity Loads releases control), the EVCS automatically falls back to its own built-in algorithm. In this fallback state, if battery or grid power is permitted in the EVCS surplus charging configuration, charging may start even without available solar surplus. To prevent this, it is recommended to disable the following setting in the EVCS via its web interface or VictronConnect:

[en] Navigate to: Settings → System Setup → Opportunity Loads → EV Charging Station

[en] Maximum charging power

[en] Limits the maximum power the EVCS may use as a controlled load, even if more surplus is available. This can reserve surplus for lower-priority loads, improve parallel operation with other Opportunity Loads, and reduce load fluctuations in smaller systems.

[en] Remember detected EV phases

[en] Stores the previously detected EV phase configuration (1-, 2-, or 3-phase) and reuses it for subsequent sessions, reducing phase-detection delays and improving charging start-up behaviour. Recommended only when a single EV is regularly connected, or when all EVs using the station share the same phase configuration. Enabling this setting with vehicles of different phase configurations may prevent some vehicles from charging correctly.

[en] Steps to configure a Shelly device as an Opportunity Load:

[en] Navigate to Settings → Integrations → Shelly Devices and enable the devices. [en] In the device list, navigate to the Setup section and configure the Position and Phase Setting. [en] Navigate to the Switches configuration and set the function to Opportunity load. [en] The device will now appear as a controllable load under Settings → System Setup → Opportunity Loads, where load parameters can be configured.

[en] Navigate to: Settings → System Setup → Opportunity Loads → Shelly Device

[en] Expected power consumption

[en] The typical power draw of the connected load while active. The GX device uses this value to estimate available surplus capacity, decide when to activate the load, and coordinate parallel operation. For best results, the load should consume close to the configured value when on, and close to 0 W when off.

[en] If the load's consumption varies within a known range, configure the highest expected value. This ensures the load is not switched off prematurely after its minimum run time. Opportunity Loads will refine its estimate during runtime. Avoid loads with strongly unpredictable consumption, as this reduces control accuracy.

[en] Minimum run duration when turned on

[en] The minimum time the load remains active after being switched on. Prevents excessive switching during fluctuating PV production, reduces short operating cycles, and protects connected equipment. Particularly important for loads with compressors, pumps, heating elements, or mechanical switching components.

[en] Minimum rest duration when turned off

[en] The minimum time the load remains off after being switched off. Reduces rapid switching, protects equipment, and stabilises system operation during changing solar conditions.

[en] Recommendation for multiple loads: Configure longer rest durations for lower-priority loads. When solar power decreases, loads are shed starting from the lowest priority. If lower-priority loads use the same rest duration as higher-priority ones, they may become available again too quickly — only to be turned off again shortly afterwards. Staggered rest durations help avoid unnecessary switching.

[en] For systems with multiple Opportunity Loads, it is recommended to configure longer rest durations for lower-priority loads.

[en] When available solar power decreases, loads are disabled starting with the lowest-priority load. If multiple loads use the same rest duration, a lower-priority load may become available again too quickly, only to be switched off again shortly afterwards when a higher-priority load becomes available again.

[en] Staggered rest durations help avoid unnecessary switching.

[en] Once configured, operation is fully automatic. The GX device continuously monitors PV production, battery SoC, AC consumption, and configured Opportunity Loads. Based on available surplus and configured priorities, it dynamically activates, adjusts, or disables controlled loads.

[en] The algorithm accounts for AC-coupled and DC-coupled PV, DC-to-AC conversion efficiency, phase balancing, feed-in permissions, and whether the system is grid-connected or off-grid. It processes loads in priority order, applies Priority-Aware Best Fit to avoid wasting surplus, and rebalances active loads automatically as conditions change — for example when cloud cover reduces PV output, a large household load switches on, or battery charging requirements increase.

[en] When the grid or AC generator connection is lost, controlled loads are shed as much as possible to support system stability. After approximately one minute, Opportunity Loads may resume if sufficient surplus is available and system conditions are stable. If Pause Opportunity Loads if no AC input is connected is enabled, loads remain paused until AC input returns.

[en] In ESS setups using BatteryLife, Opportunity Loads automatically pauses when the active SoC limit reaches 85% (if that preference is enabled) and resumes once the battery has sufficiently charged and BatteryLife lowers the active SoC limit again. This prioritises a full battery charge during periods of poor solar yield.

[en] While PV production is available, Opportunity Loads actively enforces the expected state of controlled devices. If a device is manually switched on externally (e.g. via a Shelly app or physical button) when Opportunity Loads expects it to be off, the system will switch it off again. To take manual control temporarily, disable Auto — Opportunity Loads will release control immediately and not resume until Auto is re-enabled.

[en] During periods without meaningful PV production, Opportunity Loads enters an inactive state and releases control of all devices. This allows devices to follow their own local schedules or configurations overnight — for example, a Shelly-controlled boiler can run a local schedule to reach a target temperature during the night if it was not reached during the day due to poor solar yield.

[en] Opportunity Loads is designed to use surplus solar energy, but brief battery usage can occur — for example when a load cannot be switched off immediately due to its minimum run time, or when PV production drops suddenly. In critical situations (e.g. sudden loss of AC-coupled PV combined with high inverter load), inverter/charger protection mechanisms may enforce immediate load shedding regardless.

[en] SoC probing is used in off-grid and zero-feed-in systems where excess PV cannot be exported. When the battery nears 100% SoC, the system must curtail PV generation, masking the solar array's true output. To determine actual available surplus, Opportunity Loads temporarily allows the battery to discharge to approximately 97% SoC by activating controlled loads. This unthrottles PV, revealing the full available power. The system returns to normal solar-only operation once the SoC decreases.

[en] Opportunity Loads can be manually overridden at any time via the GX device New UI or VRM:

[en] When a manual override is active, the device no longer follows the Opportunity Loads algorithm until automatic control is re-enabled. This allows a load to be operated immediately even when insufficient solar surplus is available.

[en] Opportunity Loads can be monitored remotely through VRM, including live control of supported devices (EVCS via the Control Pane, Shelly devices via the Switch Pane). Configuration of priorities, battery settings, preferences, and device parameters is only available on the GX device itself or via Remote Console.

[en] VRM also provides:

[en] System Overview chart: displays actual and forecasted energy consumption alongside PV production, broken down by category (base load, EV charging, AC loads, heating), helping visualise how solar energy is distributed throughout the day. [en] Consumption dashboard: shows energy consumption by source (solar, battery, grid, generator) over time, allowing users to quantify the improvement in self-consumption and reduction in grid dependency.