NKON ESS & Victron
From connection to control

How NKON ESS and Victron work together

An NKON ESS battery stores DC energy. A Victron MultiPlus or Quattro converts that energy to AC for the connected loads and can charge the battery from an AC source. A GX device, such as a Cerbo GX, coordinates the system and makes its operating data available locally and through the Victron Remote Management portal, usually called VRM.

The battery management system, or BMS, monitors the battery and communicates the charge and discharge limits that the Victron system must respect. An energy meter measures the exchange with the grid. Solar energy can enter through an AC-coupled PV inverter or through DC-coupled Victron MPPT solar chargers; the configuration depends on which arrangement is installed.

Scope of this guide. The source example uses an NKON ESS Pro of approximately 32 kWh, a Cerbo GX, Lynx distribution and three MultiPlus 3000 units. The same principles can help explain other compatible Pro and Eco installations, but capacity, current limits, firmware and wiring must be checked for the exact battery and inverter models. A 3000 VA inverter rating should not be treated as 3000 W of continuous output in every operating condition.

These diagrams explain the system architecture. They do not replace the installation drawings, protection design, cable sizing, earthing arrangements or grid-code settings for the site. Electrical installation and commissioning should be carried out by a qualified installer familiar with Victron systems and lithium batteries.

Check the hardware before changing settings

Start with a record of the battery model, BMS revision, number of modules, nominal voltage, rated capacity and permitted charge/discharge currents. Record the MultiPlus or Quattro models, the GX device and the meter. Use the battery’s current model-specific documents and compatible Victron firmware. Save the existing configuration before making changes, and plan updates so that a loss of power cannot interrupt them.

• Confirm that the selected battery revision supports the intended Victron integration.
• Check the DC protection, isolators, polarity, conductor sizes and connection torques against the component manuals and installation design.
• Identify which loads are connected to the inverter AC output and which remain on the grid side.
• Confirm the grid connection, phase arrangement and permitted import/export behaviour.
• Make sure all expected battery modules are online before deriving the available capacity or power.
• Keep the battery BMS connected and functional throughout normal operation.

Parallel batteries

The supplied guide describes a parallel arrangement with up to 16 units. Treat that as the scope of the documented arrangement, rather than a maximum for every NKON Pro or Eco revision. Check the current model-specific instructions for the permitted unit count, addressing, master battery, communication sequence and protection.

The source describes RS485 links between the battery modules using straight network cables, with the appropriate RS485 A/B ports connected in sequence. Follow the port labels and connection order for the actual battery. These links are separate from the CAN connection between the battery system and GX device. Similar RJ45 connectors do not make CAN, RS485, Ethernet and VE.Bus interchangeable.

Connect the battery to the GX device

The integration described here requires a GX device running Venus OS. It receives the battery’s limits and status and passes the appropriate control information to compatible Victron equipment. Establish reliable communication before relying on battery readings or configuring charging behaviour.

1. Select the battery protocol. On the battery display, open Menu → Protocol → CAN_VICTRON and confirm the selection. The exact menu wording can vary with BMS firmware.
2. Use the specified Type A cable. The supplied guide identifies a Victron VE.Can to CAN-bus BMS Type A cable, part number ASS030710018. Check the approved cable for the actual NKON revision; the current Victron cable reference also lists ASS030710118.
3. Connect the labelled ends. Connect the Battery BMS end to the battery CAN port and the Victron end to the appropriate GX CAN interface. Do not connect it to VE.Bus or an Ethernet socket.
4. Configure the GX CAN interface. Select CAN-bus BMS (500 kbit/s) on the interface used by the battery. The source shows Settings → Services → VE.Can; newer Venus OS versions can place connectivity settings elsewhere.
5. Check bus termination and detection. Follow the GX and battery instructions for termination, then confirm that a managed battery appears in the device list and supplies plausible live readings.

Cable diagram clarification. The source illustration and the current Victron Type A reference differ in their battery-side ground-pin assignment. Do not use this illustration as a cable-manufacturing drawing. Confirm the correct pre-made cable and pinout for the exact battery revision before connecting it. Victron CAN-bus BMS cable reference ↗

If communication is lost, investigate the cable, selected interface, termination, protocol and firmware. The system must respond safely to missing BMS information. The source mentions a five-minute shutdown period, but the actual response must be verified for the specific equipment and firmware; it should not be used as a universal timeout guarantee.

Understand the limits before adjusting them

Open the battery in the GX device list. Check the overview, cell information and parameters. The supplied screenshots use example device names, including LBSA SMARTBMS and BMS16S300A-SP136. The name shown by an actual NKON battery can depend on its BMS and firmware. A visible battery name or SoC reading is only the first check; the limits and alarms must also be communicated correctly.

Also check the highest and lowest cell voltage, temperature readings, installed/online module count and any module that blocks charging or discharging. These details often explain a reduced current more clearly than the overall SoC alone.

About the voltage ranges in the source. The original text gives several inconsistent CVL ranges and typical values. This page therefore does not turn those ranges into a fixed operating specification. Use the current battery instructions and the BMS’s valid live limits for the installed revision.

Why the numbers move during normal operation

VEConfigure and the ESS Assistant

Use the configuration method appropriate to the installed MultiPlus or Quattro system. In a parallel or three-phase installation, first confirm the system arrangement and applicable grid code. The settings below reproduce the supplied NKON example so that each value has a clear purpose. They are not generic LiFePO₄ defaults for unrelated batteries.

Grid connection matters. A valid grid-code configuration is needed for grid-connected ESS operation, including systems where deliberate export is not intended. The installer must select the applicable code and verify the resulting operation. Victron ESS configuration manual ↗

Inverter tab

Which limit actually controls the system? These values are not the complete protection strategy. When the ESS Assistant’s dynamic cut-off is active, all three Inverter-tab settings—low shutdown, restart and pre-alarm—are overridden by the Assistant’s dynamic cut-off and restart settings. The three values above document the source configuration; they are not the operative ESS thresholds. Do not treat the 43.20 V entry as a target discharge voltage or as permission to override a BMS stop request.

Charger tab

Select the lithium iron phosphate battery type and enable the lithium setting as shown in the guide. Then check the charging profile and the maximum charger current.

Virtual switch and Assistant selection

On the Virtual switch tab, select Do not use VS. Open Assistants, add the ESS Assistant and start its configuration. The supplied procedure uses the ESS Assistant rather than the older virtual-switch method.

1. Select the battery system. Choose System uses LiFePO₄ with other type BMS, as shown in the source.
2. Enter total capacity in Ah. Use the rated Ah capacity of the complete battery bank at its nominal voltage. For the example, 628 Ah × 51.2 V = 32,153.6 Wh ≈ 32.15 kWh. Add the Ah capacities of approved parallel modules; do not add their voltages.
3. Keep the chosen battery type. Select Do not change battery type at the relevant Assistant step.
4. Check sustain voltage. The supplied example uses 50.00 V.
5. Check the dynamic cut-off curve. The example sets all four displayed points to 46.00 V.
6. Check restart offset. The example uses 2.00 V above cut-off(0).

Source correction. The original prose labels the last dynamic cut-off point as 1 C, while its screenshot labels it 2 C. The image above is retained unchanged and its caption follows the visible label. Confirm the actual Assistant fields and approved NKON values for the installed revision before commissioning.

A C-rate expresses current relative to capacity: for a 628 Ah battery, 0.25 C corresponds to 157 A. This definition helps explain the curve; it does not mean the battery or inverter is approved to operate at every C-rate shown in the Assistant.

Leave the internal battery monitor enabled. The NKON guide warns that disabling it on the VEConfigure General tab after configuring ESS clears the stored battery capacity. The GX device can still use the managed battery’s SoC as its system measurement.

Connect and verify the VM-3P75CT meter

A grid meter lets the ESS see the site’s actual import and export. Its measurement boundary, phase assignment and current-transformer direction must match the installation. A reversed reading can cause the system to respond to the wrong condition.

Configure the VM-3P75CT in VictronConnect with Role: Grid meter, select the correct phase arrangement and confirm the network settings. For Ethernet discovery, connect the meter and GX device to the same local network; DHCP is normally the starting point. The source screenshots show discovery through the GX device’s Modbus TCP/UDP menu; newer versions may use Settings → Integrations → Modbus Devices. VM-3P75CT configuration guide ↗

1. Open Modbus TCP/UDP devices in the GX settings.
2. Select Scan for devices and start a scan.
3. Open Discovered devices.
4. Enable the discovered VM-3P75CT, then confirm it appears in the device list with the correct role.

If the meter is connected by VE.Can instead, use the correct 250 kbit/s interface and termination. Keep it separate from the battery’s 500 kbit/s CAN-bus BMS connection.

GX device and DVCC settings

After the battery is detected, open its Parameters page and compare the reported CVL, CCL and DCL with the battery’s condition and model-specific limits. Check the online module count. A fully charged battery can legitimately report a reduced CCL.

DVCC stands for Distributed Voltage and Current Control. In this integration it coordinates compatible chargers using the managed battery information. The following table documents the source configuration, including settings that should be reviewed rather than copied without context.

DC solar export exception. When DC-coupled PV export is enabled, the DVCC charge-current cap is not applied to the relevant MPPTs in the usual way. Their local current limits and voltage control remain important. Review MPPT limits before enabling this export option. Victron DVCC limits and ESS exception ↗

ESS modes, reserve and grid settings

Open Settings → ESS. Decide whether the installation primarily cycles energy for self-consumption or keeps the battery ready for a grid outage. Then set the meter, load arrangement and reserve to match the site.

For the pictured grid-meter installation, select the appropriate external meter. Set whether the inverter AC output is used and whether battery energy serves all measured system loads or only critical loads. Confirm the phase-control strategy for the actual installation; the screenshot’s Total of all phases is an example.

Minimum SoC and the active SoC limit

The configured minimum SoC is the normal reserve setting while the grid is present. BatteryLife can raise the active limit above it. In the source screenshots, the configured minimum is 10% while the active limit is 15%. Those two readings are therefore not inherently contradictory.

During a grid outage, ordinary minimum-SoC behaviour changes: backup operation remains subject to battery protection and the system’s shutdown criteria. The installer must explain which circuits are backed up and test the approved outage behaviour.

Peak shaving

Peak shaving lets the battery assist when AC demand would otherwise exceed the configured threshold. The source shows Always, with system AC import and export current limits disabled. This is an example configuration, not a reason to disable limits on every installation.

Always can use energy below the ordinary minimum SoC to support peaks. That may reduce the energy reserved for an outage. Choose the setting and AC current limits together with the site’s connection rating, load profile and backup priority. ESS peak-shaving configuration ↗

Grid feed-in and solar topology

The guide shows AC-coupled PV — feed in excess: Enabled, DC-coupled PV — feed in excess: Disabled, and Limit system feed-in: Disabled. First identify how the solar array is connected. AC-coupled solar reaches the AC installation through a PV inverter; DC-coupled solar charges the battery/DC bus through an MPPT.

Enable feed-in only where the connection, contract and installation allow it, and configure required limits in the appropriate control layer. Simply having solar panels is not a reason to enable DC-coupled export. The source’s Feed-in limiting active: No is a status reading, not proof that unrestricted export is permitted.

MPPT solar charger settings

This section applies when Victron MPPT chargers are connected to the battery/DC bus. It does not describe the setup of a separate AC-coupled solar inverter.

1. Select User Defined as the battery preset.
2. Check the source values: 57.60 V absorption and 55.20 V float.
3. Enable expert mode where required to access the relevant fields.
4. Select a fixed absorption curve with an absorption time of 1 hour, as in the supplied guide.
5. Set each charger’s maximum current so that the complete installation remains within the permitted charging capability.
6. Verify that the charger participates in the intended managed-battery control and that BMS communication and alarms are working.

The local charging profile and the BMS’s live commands serve different roles. A stored absorption value is not evidence that the charger should continuously drive the battery to that voltage. When several chargers operate together, check the combined current and the DC-export exception described in the DVCC section.

Dynamic ESS in the VRM Portal

Dynamic ESS adds planning to the NKON ESS and Victron system. It coordinates charging, stored energy and permitted export using your electricity tariff, expected consumption and solar forecast. It can charge during favourable periods and reserve energy for later use. Results depend on your contract, weather, consumption and equipment; switching it on does not guarantee savings. A correct installation and reliable battery communication remain the starting point.

Before you configure Dynamic ESS

Complete the standard ESS configuration first. Confirm that the GX device sees the NKON battery, reports credible state of charge and receives its charge and discharge limits. Check grid-meter readings and the installation’s import/export direction. Use compatible, up-to-date stable firmware, a working VRM connection and an account authorised to change the installation.

Set the installation location correctly so solar forecasting is relevant. Consumption history helps the system learn the installation’s behaviour. Dynamic ESS also supports suitable fixed time-of-use tariffs; a dynamic contract is not the only possible arrangement. Check the country, provider and tariff options currently available in VRM rather than relying on a fixed country list. How Victron Dynamic ESS plans energy use.

On the GX device, the Dynamic ESS setting for operation through VRM is Auto. Configure the schedule in VRM and avoid running a second controller that competes with it. Victron Dynamic ESS mode reference.

Open the installation and setup wizard

1. Sign in to the VRM Portal and select the correct installation.
2. Open Settings, then Dynamic ESS.
3. Work through the system, battery, buying-price, selling-price and confirmation steps.

The screenshots show the source document’s interface. Menu names and placement can change between VRM versions, so identify each field by its function.

System settings and operating mode

Answer Can you sell energy back to the grid? using your actual connection agreement and energy contract. Enter the installation’s import and export capabilities. The source guide uses 17 kW as an example; it is not a setting for every installation. Your installer must account for the grid connection, phase arrangement and equipment.

Green mode prioritises household consumption and battery charging before exporting surplus solar energy. Battery energy is reserved for consumption, while useful charging from the grid can still occur. Trade mode also uses battery storage for permitted export when the price calculation favours it. Choose according to your objective and contract. Victron’s explanation of Green and Trade mode.

Battery capacity and charge or discharge power

Enter the total battery capacity in kWh. The guide’s 32 kWh example is an energy quantity: it describes storage capacity. Charge and discharge limits are in kW: they describe the rate of energy transfer. The illustrated 5.5 kW values must be replaced with values appropriate to your battery bank, inverter system and installation.

For a parallel bank, use its verified combined capacity. Do not assume that adding batteries increases inverter power. Likewise, a larger inverter does not increase the battery’s permitted current. The battery-management system can reduce available charging or discharging even when the configured maximum is higher.

Battery cycle cost and balancing

The guide uses this simplified allowance for battery wear:

Battery cycle cost per kWh = purchase price ÷ (estimated full cycles × battery capacity in kWh).

For an illustrative €3,000 battery with 6,000 equivalent full cycles and 30 kWh capacity, the result is approximately €0.0167/kWh. These are calculation examples, not specifications for an NKON battery. Use supported cycle-life assumptions and their stated operating conditions. This allowance represents battery use; it is separate from the electricity purchase tariff.

Review the advanced restrictions and balancing options. A restriction can prevent an energy flow that your contract does not permit. Periodic balancing charges give the battery an opportunity to reach full charge; select the interval and duration using the applicable NKON battery guidance. A balancing period can explain why the battery remains fuller than expected. Victron’s balancing feature explanation.

The supplied NKON guide requires Optimized with BatteryLife for batteries used in regular cycling. Retain that NKON requirement. If the active SoC limit rises, review charging history and the battery’s condition with the installer before changing BatteryLife. Its reserve management and DESS balancing serve related purposes, but should not be treated as interchangeable settings.

Configure buying and selling prices

Select Fixed or Dynamic prices as applicable, then choose the correct country and provider. The guide illustrates Netherlands–Tibber; this is an example. Select the price interval that matches the contract, such as 15 or 60 minutes where available.

Check buying and selling separately. A suggested formula is a starting point: confirm that fees, taxes and other applicable components reproduce the prices you actually pay or receive. Compare several time periods with the provider’s published prices. A green validation mark confirms a formula is accepted, not that it matches your contract.

Activate and verify operation

Submit the reviewed configuration. Open Controls and confirm that Dynamic ESS is on. For the procedure in this NKON guide, retain Optimized with BatteryLife as the ordinary ESS mode. Do not select the separate ESS External control mode merely because those words appear in the dashboard.

Check that VRM shows a valid DESS plan, current data and no relevant errors. Compare planned activity with actual battery and grid power over time. The dashboard’s External control status is part of the source example; that label alone does not establish that DESS is correctly configured. Avoid combining ordinary scheduled charging with DESS, because it interferes with the plan. Victron Dynamic ESS setup and troubleshooting.

Commissioning and handover checklist

A saved setting is not the same as a verified installation. After configuration, reopen the settings and confirm that the intended values remain stored. Then check the resulting behaviour under controlled conditions appropriate to the site.

Keep a configuration backup and a handover record with firmware versions, battery capacity, current limits, grid limits and the reason for each installation-specific choice. Explain to the owner which settings they may adjust and which require installer review.

For a problem that needs support, include the battery model, BMS and Venus OS versions, module count, recent alarms, relevant settings and screenshots of the live battery parameters. Contact [email protected]. Share only the installation information needed to diagnose the issue.

Troubleshooting common questions

Start by comparing the requested operation with the live limits and measured power flow. Avoid raising limits simply to make a warning or restriction disappear.

The terms used in this guide

ESS

Energy Storage System. In Victron terminology, the configured system that manages battery storage and power exchange.

DESS

Dynamic ESS. Planning that uses tariffs, forecasts and installation capabilities to schedule operation.

BMS

Battery Management System. The battery’s monitoring and protection system, which communicates operating limits.

GX and Venus OS

The GX device is the system controller/monitor; Venus OS is its operating software.

DVCC

Distributed Voltage and Current Control. Coordination of supported chargers using shared system and managed-battery information.

VRM

Victron Remote Management. The online portal for monitoring and supported remote configuration.

kWh, kW and A

kWh measures energy capacity; kW measures power; A measures current. They are not interchangeable.

Ah

Ampere-hours. Charge capacity; multiplying Ah by nominal voltage gives an approximate energy capacity in Wh.

AC-coupled PV

Solar generation connected through a PV inverter to the AC installation.

DC-coupled PV

Solar generation connected through an MPPT charger to the battery/DC side.