Solar Dynamic Load Management

1. Solar dynamic load management

Needed version

Firmware v5.33.4 or above is recommended for this feature.

What's new in 5.33.4

Solar charging functions within the DLM feature have been introduced with firmware 5.32.0, functionally extended with 5.33.0 and 5.33.4.

• Added support for switching between single-phase and three-phase charging with an additional 2-phase contactor
• Extended the list of meters that can be used for Solar DLM with measurement at the grid connection point: TQ EM420, Siemens PAC2200, Phoenix Contact MB371 and ABB B23
• Reworked the names and descriptions of functions and Solar DLM operating modes to make the use clearer to the operator

1.1. Introduction

The Dynamic Load Management function may be used to synchronize the consumption of electric vehicles with the production of a local PV system. A typical use case for this function is to charge selected vehicles with inexpensive self-produced electricity instead of relative costly energy from the public grid.

1.2. How the algorithm works

1.2.1. Overview

• The algorithm will assign the PV energy production first to all (if any) non-solar-mode connectors and distribute the remaining energy to the solar-mode-enabled connectors. This concept will prevent solar chargers from charging with electricity from the public grid.
• Solar-mode-enabled connectors will receive energy based on the first come first serve principle.
• Non-solar mode connectors in the DLM will charge electric vehicles with energy from PV system or from the grid, depending on PV production.
• Note: The algorithm assumes the use of a balancing grid meter and will distribute the current independently from the phase of production and consumption (-3600 W PV generated on L3 and car charging +3600 W on L3 = 0 W).
• Calculation is based on Active Current for Solar DLM.

1.2.2. Metering

• With solar charging, the meter locations 'Renewable Production' and 'Grid' are supported.
• With the meter location 'Renewable Production', the system optimizes to fully use the locally generated PV energy. With the meter location 'Grid' the system optimizes to not use the capacity of the grid connection at all, but to steer the total power of the grid connection meter close to 0W.

1.3. Solar modes

1.3.1. Basic charateristics

Mode	PV charging active	Uses grid power?	Switches to 1ph to reduce min. charging power to 1.4 kW
DLM standard
PV surplus
PV surplus + grid support
PV surplus with 1ph/3ph switch
PV surplus + grid support with 1ph/3ph switch

1.3.2. Mode descriptions

Mode	Description	Best For
PV surplus	Maximizes the use of solar energy by charging EVs exclusively with excess PV power. Charging only occurs when surplus power exceeds the minimum threshold (6A per phase).	Users who prioritize charging with self-produced energy and want to minimize grid dependency.
PV surplus + grid support	Balances solar optimization with charging reliability by supplementing insufficient PV production with a configurable amount of grid power. The system intelligently reduces grid consumption as PV production increases.	Installations that need reliable charging while still prioritizing renewable energy usage.
PV surplus with 1ph/3ph switch	Enhances solar utilization through dynamic phase switching. When PV production is limited, the system automatically switches from 3-phase (4.14 kW minimum) to 1-phase charging (1.38 kW minimum).	Smaller PV systems where maximizing charging time with limited solar power is important.
PV surplus + grid support with 1ph/3ph switch	Combines the benefits of grid support and phase switching for maximum flexibility. Uses dynamic phase management and intelligent grid supplementation to optimize charging under all conditions.	Installations requiring maximum flexibility and efficiency in all weather conditions.
DLM standard	Operates as a conventional DLM system without solar optimization. All chargers use available power from any source (grid or PV) according to standard DLM rules.	Situations where solar optimization is not required or when maximum charging speed is the priority.

tip

You can change the solar mode at any time, even during an active charging session, allowing you to adapt to changing conditions or requirements.

1.4. Compatible meters

See here.

1.5. Understanding hold times

The Solar DLM system uses several hold times to ensure stable operation:

• Phase Switching Hold Time:

  • Purpose: Ensures stable power before switching phases
  • Prevents rapid phase changes that could damage vehicles
  • Configurable via the parameter Phase Switching Stability Time
  • Options: very fast (1 min), fast (3 min), medium (5 min), slow (15 min)
  • Shorter times increase efficiency but may cause cycling

• PV Surplus Monitoring Time:

  • Purpose: Ensures stable PV surplus before resuming charging
  • Prevents rapid cycling between charging and paused states
  • Configurable via the parameter PV Surplus Monitoring Time [s]
  • Applied after charging was previously paused due to insufficient PV surplus

• Waiting Time After Phase Switching:

  • Purpose: Allows vehicle to stabilize after phase changes
  • Important for vehicle compatibility and safety
  • Configurable via the parameter Waiting time after phase switching to resume charging [s]
  • Some vehicles (like Renault ZOE) require longer times or are incompatible

1.6. Best practice configurations

1.6.1. Grid connection setup (optimized for reliability)

Parameter	Value
External Meter Location	Grid
Configure solar charging mode	PV surplus + grid support
Maximum Grid Support Current [A]	16
Software function to use phase switching	Enabled
Hold Times:
Phase Switching Stability Time	Medium (5 min)
PV Surplus Monitoring Time [s]	60s
Waiting time after phase switching to resume charging [s]	120s

1.6.1.1. Explanation:

This setup prioritizes reliable charging while still optimizing for solar energy usage. It uses the grid to supplement when necessary, ensuring consistent charging.

1.6.2. Pure solar setup (maximized self-consumption)

Parameter	Value
External Meter Location	Renewable Production
Configure solar charging mode	PV surplus
Maximum Grid Support Current [A]	0
Software function to use phase switching	Enabled
Hold Times:
Phase Switching Stability Time	Medium (5 min)
PV Surplus Monitoring Time [s]	60s
Waiting time after phase switching to resume charging [s]	120s

External Meter Location: Renewable Production Configure solar charging mode: PV surplus Maximum Grid Support Current [A]: 0A Software function to use phase switching: Enabled Hold Times:

• Phase Switching Stability Time: Medium (5 min)
• PV Surplus Monitoring Time [s]: 60s
• Waiting time after phase switching to resume charging [s]: 120s

1.6.2.1. Explanation:

This setup maximizes the use of solar energy, prioritizing self-consumption over grid usage. Charging only occurs when excess PV power is available.

1.6.3. Evening charging setup (time-based approach)

Parameter	Value
External Meter Location	Renewable Production
Configure solar charging mode	PV surplus
Enable Solar Mode Pause	On
Start Time of Solar Mode Pause	18:00
End Time of Solar Mode Pause	06:00
Maximum Grid Support Current [A]	0

1.6.3.1. Explanation:

This setup prioritizes solar charging during the day and allows grid charging during the night. It's useful for installations where solar production is inconsistent.

1.7. Considerations for implementation

1. Vehicle Compatibility

   • Some vehicles like the Renault ZOE are not compatible with phase switching
   • Test compatibility before enabling phase switching features
   • Consider using longer waiting times (120s) for sensitive vehicles

2. PV System Sizing

   • For 3-phase charging without phase switching, ensure PV system can produce at least 4.2 kW
   • For 1-phase charging, a minimum of 1.4 kW is required
   • Phase switching can help utilize smaller PV systems more effectively

3. Meter Placement

   • Grid location: Optimizes to keep grid power close to zero
   • Renewable Production location: Optimizes to use all available PV power
   • Choose based on your primary goal (grid independence vs. PV utilization)

4. User Experience

   • Consider enabling "Allow User to Control Solar Mode" for flexibility
   • Use "Solar Mode Pause" for predictable charging during specific times
   • Balance solar optimization with user charging needs

1.8. Usage

• Enable the Solar Mode on the DLM Master setting 'Configure solar charging mode' and choose one of the solar modes.
• Connect an external meter to the DLM Master, that measures the (positive) energy production of the PV system. Set the meter location to either 'Grid' or 'Renewable Production'.
• Select one or multiple chargers (DLM slaves) to use the PV energy when and to the extent available by setting 'Enable Solar Mode on This Charger' to 'On'.

1.9. Limitations

• Some cars - like the Renault ZOE - are not compatible with the phase switching function.
• In the mode 3 system, a charging station must provide 6A or more when charging. EVs with 3-phase-chargers will therefore need to receive at least 4.2 kW of power. In case the PV system provides less power, charging will be paused.
• Phase switching requires additional hardware (2-phase contactor) and proper configuration.

1.10. Configuration

Category	Parameter	Description
Load Management / DLM	Configure solar charging mode	This DLM feature allows EVs on a group of DLM clients to be charged with excess PV power. Activate solar mode on one or more participating DLM clients. The function requires a meter at the grid connection point or at the solar inverter. In 'PV surplus' mode, the EV is charged when there is enough surplus power to charge at the defined minimum current. EVs in this mode charge mostly without energy from the grid. The 'PV surplus + grid support' mode uses a defined power contribution from the grid to enable charging when PV production is insufficient. This allows the vehicle to be charged primarily with self-produced energy.
Load Management / DLM	Maximum Grid Support Current [A]	This current will be supplemented from the grid to sustain EV charging in case the PV surplus does not reach the threshold for charging. The supplement will be gradually reduced the more PV surplus is generated. The default of 18A allows to charge with 3 phases with 6A per phase.
Load Management / DLM	PV Surplus Monitoring Time [s]	Period for which the preconditions for available PV power needs to be met before charging the EV is resumed. It is applied after charging was previously paused due to insufficient PV surplus.
Load Management / DLM	Phase Switching Stability Time	The DLM algorithm monitors the available PV surplus during the holding time for the charging station. A switching operation (1ph <> 3ph) is only triggered if the current remains stable above or below the calculated phase switching current threshold. The hold time can be very fast (1 minute), fast (3 minutes), medium (5 minutes) or slow (15 minutes). Shorter holding times generally increase efficiency, but can lead to undesirable cycle behaviour and wear.
Load Management / DLM	Enable Solar Mode Pause	This setting temporarily disables solar mode for the entire DLM system for a defined period of time to charge EVs, regardless of PV surplus. This feature can be used to attempt to charge with PV surplus throughout the day, but definitely charge in the evening.
Load Management / DLM	Start Time of Solar Mode Pause	From this start time, all solar chargers in the DLM will temporarily be controlled like standard DLM chargers.
Load Management / DLM	End Time of Solar Mode Pause	From the end time, the preset solar charge mode is reactivated on all charging stations configured as solar chargers.
Load Management / DLM	Enable Solar Mode on This Charger	This parameter is used to signal to the DLM master that the charging station is participating in solar charging. The DLM master then checks whether there is sufficient excess PV power in the current solar charging mode to charge the vehicles connected to the station. Participation in solar charging can be terminated during a charging process if desired (setting: "Off"). In this case, the normal DLM algorithm is applied.
Load Management / DLM	Allow User to Control Solar Mode	If set to 'On', users with the 'user' role will see the solar mode parameter on the 'Load Management' page and have permission to enable or disable solar mode on this charger.
Load Management / DLM	External Meter Location	Specifies how the external meter is connected depending on its location. Either at the grid entry point, between an external load and the rest of the installation, or to a renewable energy source such as a solar panel.
Installation	Software function to use phase switching	The selected software function can exclusively use the phase switching relay. 'Off' means that phase switching between 1ph and 3ph is disabled.
Installation	Waiting time after phase switching to resume charging [s]	Wait time after switching phases before closing the contactor again. Important: Some vehicles require 120s to avoid damage. Always check compatibility with the vehicle manufacturer.
Manufacturer	Type of phase switching relay (NO/NC)	The type of contactor / relay used for phase switching can be configured as normally open or normally closed.
Manufacturer	Use phase switching relay (1ph <> 3ph)	This function allows the operator to use an additional built-in relay or contactor to switch phases 2 and 3 on and off. The switch can be connected to a relay output of the charge controller. The main purpose of this function is to reduce the minimum charging power required by IEC61851-1 mode 3 from 4,140 watts to 1,380 watts. Important: not all vehicles are compatible with this function and may exhibit defects after switching.