ESS Design and Installation Manual - VE.Bus

Update all system components to the latest firmware version:

The following settings must be made in VEConfigure before the system will operate correctly. For general guidance on using this tool, see the VEConfigure manual.

General notes

Low battery warning levels

Before configuring the ESS menu, set up the AC system so the inverter/charger knows what is connected to each AC input and where the loads are located. These settings are found under Settings → System Setup → AC System.

AC input 1: Set the role of the first AC input: Not available, Generator, Grid, or Shore power. Set the input to Generator when a generator is connected. The system will then enable generator charging and load the generator correctly while it is running. Additional configuration is required to complete the setup of these options.

AC input 2: Set the role of the second AC input, using the same options as AC input 1. On a Quattro, AC-In 1 has priority over AC-In 2, so the usual arrangement is the grid on AC-In 1 and the generator on AC-In 2. Reverse it, wiring the generator to AC-In 1 and the grid to AC-In 2, only where the generator must take priority over the grid, which allows forced generator intervention even when the grid is available.

Position of AC loads: Tell the system where the AC loads are connected relative to the inverter/charger, so they are displayed and accounted for correctly: AC input only : the AC output of the inverter/charger is not used. AC output only : all AC loads are on the output of the inverter/charger. AC input & output : the system automatically displays loads on the input of the inverter/charger if a grid meter is present. Loads on the output are always displayed.

Monitor for grid failure: When enabled, the system monitors for loss of the AC input and triggers an alarm if it is detected. The alarm clears when the AC input is reconnected.

The Mode setting determines the overall strategy the system uses to manage the battery, grid, and solar. It is found under Settings → System Setup → ESS → Mode. Four modes are available.

Mode: Select the operating strategy for the system. Keep batteries charged The battery is discharged only during a failure of the utility grid. Once the grid is restored, the battery is recharged from the grid, and from solar when available. Use this mode where the battery's primary purpose is backup rather than self-consumption. Optimized with BatteryLife and Optimized without BatteryLife When excess PV power is available, it is stored in the battery. That stored energy is used later to power the loads when there is a shortage of PV power. The two Optimized modes differ only in whether the BatteryLife algorithm is active: Optimized with BatteryLife dynamically manages the minimum SOC so the battery is regularly recharged to a healthy level, protecting battery life. This is the recommended mode for most systems. See BatteryLife for a full explanation. Optimized without BatteryLife holds the minimum SOC fixed at the configured value, without the daily adjustment. External control The ESS control algorithms are disabled. Use this mode where the system is driven by an external controller running its own control loop.

Determines whether the battery is used to supply loads on the AC-In side of the inverter/charger while the grid is connected. It has an effect only when loads are present on the AC-In side; in a system where all loads are on the AC-Out, there is nothing on the AC-In for it to act on.

Self-consumption from battery: All system loads : the battery supplies both the loads on the AC-Out and the loads on the AC-In. Power is drawn from the battery to cover the whole system, so self-consumption extends to loads on the grid side of the inverter/charger. Only critical loads : the battery supplies only the loads on the AC-Out. Loads on the AC-In are still covered by solar when it is available, with any shortfall taken from the grid, but the battery is not discharged to cover them.

Peak shaving limits the power drawn from, or fed into, the utility grid at the grid connection point. When demand exceeds the configured limit, the battery supplies the difference; when export would exceed the limit, the system reduces solar production and battery discharge. This allows a system to support loads that exceed the capacity of the grid connection, and to operate within a contracted or physically limited grid connection.

With and without a grid meter

Peak shaving is available in two forms, depending on whether the system has a grid meter.

Without a grid meter, peak shaving is performed by the inverter/charger itself, using the AC input current limit. That limit is the threshold for the AC current at the AC-In of the inverter/charger, and it applies to current in both directions, so it also caps the current fed back into the grid. When the loads exceed the limit, the battery supplies the difference. Use this method for peak shaving in any system without a grid meter, including systems that use AC current sensors connected directly to the inverter/charger.

With a grid meter, peak shaving acts on the current measured at the grid connection point, using the import and export current limits set on the GX device. It therefore applies to the whole system, including high-power loads installed on the AC-In of the inverter/charger, such as EV chargers and heat pumps. This is the form to use when there are loads on the AC-In side.

Peak shaving: determines when the battery is used to shave peaks. Above minimum SOC only (default in the Optimized modes): peak shaving operates only while the battery is above the minimum SOC. Below the minimum SOC, the battery is not discharged to shave peaks. Always: peak shaving operates regardless of SOC, so the battery is used to shave peaks even below the minimum SOC. The following two settings act on the current measured at the grid connection point and require a grid meter. Limit system AC import current: when enabled, the field 'Maximum system import current (per phase)' appears. Set the maximum current to be drawn from the grid per phase. When demand would exceed this limit, the battery supplies the difference. Limit system AC export current: when enabled, the field 'Maximum system export current (per phase)' appears. Set the maximum current to be fed into the grid per phase. When production would exceed this limit, solar production and battery discharge are reduced.

How peak shaving works

In an installation with a grid meter, the system continuously monitors the current at the grid connection point and acts to keep it within the configured limits:

Peak shaving and the Mode setting

Peak shaving operates in all modes, but the way the battery is managed around it differs.

In the Optimized modes, the battery is also used for self-consumption, so its state of charge varies with daily solar and load. Peak shaving draws on the capacity available above the minimum SOC. When the battery reaches the minimum SOC, the system does not force a recharge from the grid; it draws from the grid to cover the loads and relies mainly on solar to bring the state of charge back up.

In Keep batteries charged mode, the battery is held at a high state of charge and is discharged only to shave peaks or during a grid failure. This keeps the full battery capacity available for peak shaving at all times.

Requirements

Three-phase systems

In three-phase systems, peak shaving interacts with the way the system regulates power across the individual phases. For details of this behaviour, see Multiphase regulation.

Scheduled charge levels allow the battery to be charged from the grid during defined time windows. Up to five schedules can be configured, each defining a day or day pattern, a start time, a duration, and a target state of charge. This is typically used to charge the battery during off-peak tariff windows (time-of-use tariffs), to prepare the battery ahead of a known grid outage, or to give the battery a regular maintenance charge.

Scheduled charge levels are only available when Mode is set to one of the Optimized modes. They have no effect in Keep batteries charged mode, where the battery is already held at a high state of charge.

How it works

At the start time, the inverter/charger begins charging the battery from the grid. Charging continues until the duration elapses or the SOC limit is reached, whichever comes first. The period defined by the day, start time and duration is referred to as a scheduled charge window.

While a scheduled charge window is active, the ESS state on the Overview page indicates that scheduled charging is in progress.

Planning multiple schedules

Schedules can be combined to shape battery use across the day. For example, a schedule with a lower SOC target following one with a higher target allows the battery to be used down to the lower state of charge between the two windows.

This is useful when planning around known outages, such as published load-shedding schedules. For example, with outages scheduled at 8pm and again at 4am, the battery can be recharged after the 8pm outage but left to rely on PV after the 4am outage, since solar production will resume shortly afterwards.

Configuring a schedule

Each schedule contains the following settings: Enabled: turns the schedule on. The remaining settings appear only when the schedule is enabled. Day: the day or day pattern on which the schedule runs. Options are Every day, Weekdays, Weekends, Monthly (the first day of each month), or an individual day of the week. Start time: the time at which grid charging begins. Duration: the length of the charging window. SOC limit: the state of charge the battery is charged to during the window, using power from the grid. Self-consumption above limit: appears when the SOC limit is set below 100%. Determines how the battery behaves once the SOC limit is reached: PV: the battery is not discharged until the window ends; available PV is used to power the loads. PV & Battery: the battery is discharged for self-consumption down to the SOC limit, after which only PV is used.

Dynamic ESS optimises the system against a variable or dynamic energy tariff, scheduling battery charging and discharging to minimise energy costs while respecting the configured battery and grid limits.

For configuration and full details, see the Dynamic ESS manual.

Opportunity Loads increases self-consumption by automatically using surplus solar energy to power flexible AC loads, such as EV charging, heat pumps, water heating and thermal storage, pool pumps and e-bike charging. Rather than curtailing excess PV, or exporting it when feed-in is limited or unattractive, the GX device directs that surplus into useful work.

The GX device acts as a system-level energy coordinator. It continuously reacts to PV production, battery charging requirements, household consumption, available inverter capacity and grid availability, and allocates whatever surplus is available across the supported devices on a priority basis.

How a load is driven depends on the device. The charge current of a supported EV charging station is adjusted to track the surplus available. Other loads are switched on and off: the power the load draws is configured, and the load is switched on once the surplus is enough to cover it.

Because control is centralised in the GX device, several loads can be coordinated together, including multiple EV chargers. This avoids the conflicts that arise when devices run their own independent surplus-charging algorithms.

Supported devices are the Victron EV Charging Station and EV Charging Station NS, and Shelly devices that provide switching and energy measurement. A load with no control interface of its own is switched through one of these devices.

To be used with Opportunity Loads, an EV Charging Station must be connected to the GX device over the MQTT integration. Existing installations that use Modbus TCP can be migrated.

Opportunity Loads requires Venus OS v3.80 or later. The controls are available only in the new GX user interface.

For supported devices, requirements, and configuration, see the product manual for the GX device in use.

With ESS, the solar charge controllers:

Any charge parameters configured on the controllers themselves are ignored.

Some utilities do not permit export to the grid, or cap it at an agreed level. Where the PV is AC-coupled, keeping within that limit means reducing the output of the PV inverter itself. Limit system feed-in caps the total power fed into the grid, for both AC-coupled and DC-coupled feed-in. For that cap to take effect on AC-coupled PV, the PV inverter must be one the GX device can control, and it must be configured to accept that control. The sections that follow describe the supported PV inverters and the settings each requires.

5.19.1. Fronius PV inverters

The AC-coupled PV zero and limited feed-in feature is specifically designed and most rigorously tested with Fronius AC PV inverters. By using the Power Reduction feature in Fronius grid-tie inverters, the system can automatically reduce the output of the Fronius inverter to prevent or limit export to the grid.

Note the following:

• The earliest Fronius firmware version that can be used is 3.7.3-2.

• If more than one Fronius PV inverter is present in the system, all of them are limited.

• Zero feed-in is not supported on Fronius IG Plus inverters.

Connect the Fronius PV inverter and add it to the GX device. See AC-coupled PV with Fronius PV Inverters for detailed guidelines.

Change the following settings in the Fronius Datamanager web interface:

In the Fronius setup menu, set Data export via Modbus to tcp. In the same menu, set Sunspec Model Type to int + SF.
In Settings → DNO Editor, in the Controlling Priorities section, set Controlling via Modbus to priority 1.
By default, in Settings → DNO Editor, Dynamic Power Reduction is set to off. If the Fronius should stop generating when communication is lost, and it no longer receives instructions from Modbus control, Dynamic Power Reduction must also be configured. For this behaviour, set Export Limitation to entireSystem and DPL_SOFTLIMIT_POWERLIMIT to the export power limit, or to 0.

Checking operation

When the feature is working correctly, the Feed-in limiting active status in the ESS menu shows Yes. If it shows No, check that all of the above criteria are met. Feed-in limiting active shows No if the firmware requirement, the data export, or the Sunspec Model Type settings are incorrect, if the units are shut down (no available PV), or if the AC input is disconnected or unavailable.

Note

Do not use a Fronius Smart Meter for limiting export where ESS is used. ESS already provides the required metering. For details of when a Fronius Smart Meter can and cannot be used, see AC-coupled PV with Fronius PV Inverters.

5.19.2. ABB/FIMER PV inverters

Compatible ABB/FIMER PV inverters can also be controlled by the system so that the export to the grid can be prevented or limited.

Connect the ABB/FIMER PV inverter and add it to the GX device. See CCGX & ABB/FIMER PV Inverters for detailed guidelines.

Checking operation

When the feature is working correctly, the Feed-in limiting active status in the ESS menu shows Yes. If it shows No, check that the PV inverter is configured properly. Feed-in limiting active shows No if the firmware requirement, the data export, or the Sunspec Model Type settings are incorrect, if the units are shut down (no available PV), or if the AC input is disconnected or unavailable.