Sunsynk System Mode and Timer Settings Explained

Key Takeaways

• Sunsynk timers only function if the corresponding Grid charge and Grid signal (or Gen charge and Gen signal) options are also enabled in the battery settings.
• Timer slots must run consecutively from Timer 1 to Timer 6, and only Timer 6 can roll over midnight, requiring careful planning for overnight schedules.
• Setting Priority Load with a 100% battery target SOC during a timed charge can prevent power from reaching your home's loads until the timer ends.
• You can adjust most timer and battery target settings yourself, but grid protection and export settings are for registered persons only and require a Certificate of Compliance (CoC).

Understanding Sunsynk System Modes for Classic, Acure, and Elite Inverters

Sunsynk inverters, including the Classic, Acure, and Elite models, offer various work modes to manage how your solar system interacts with your home's loads and the grid. Selecting the correct mode is crucial for optimising energy use, especially in South Africa's load-shedding environment.

These inverters provide four primary work modes:

• Selling first: This mode prioritises sending all available power from solar, batteries, and micro-inverters back to the grid.
• Zero export + Limit to Load only: This mode prevents any export to the grid. It only supplies power to loads connected to the inverter's UPS port (load output port).
• Limited to home: This mode also prevents grid export but covers both UPS and non-essential loads. Any excess solar power will be used to charge your batteries.
• Solar export: This mode allows excess power to be sent back to the grid once your batteries are full or are charging at their maximum set current. The inverter will prioritise battery storage before exporting, and its own self-consumption will be drawn from the grid.

For Lifelynk inverters, a specific Zero Export mode is available. This allows the inverter to export power to the home load via the "GRID" connector and simultaneously power essential loads connected to the "LOAD" connector. When "zero export is ON", the inverter will export energy to the grid, but the maximum power will not exceed the total load power of the grid.

Configuring Sunsynk Timer Settings for Battery Management

Sunsynk inverters use a system of six timers to control when your batteries charge from the grid or a generator, or when they discharge. These timers are essential for managing energy during specific periods, such as before or after load-shedding slots.

To enable these functions, you must first tick the Use timer checkbox. This unlocks the six available timers.

Timer Structure and Operation

The timers operate on a 24-hour cycle and have specific rules:

• Chronological order: Timers must be set chronologically from Timer 1 to Timer 6. Timer 1 should start soon after midnight (e.g., 00:30), and Timer 6 should have the latest start time of the 24-hour period (e.g., 21:00 or 23:00).
• Midnight rollover: Timer 6 is the only timer that can roll over the calendar date at midnight and continue until Timer 1 then restarts. This is important for setting overnight charge or discharge windows.
• Default SOC: By default, the State of Charge (SOC) percentage for each timer is set to 80%. You will need to adjust this based on your energy needs.
• Factory defaults: The factory default settings for the timers are:
• • Timer 1: 01:00 - 05:00
  • Timer 2: 05:00 - 09:00
  • Timer 3: 09:00 - 13:00
  • Timer 4: 13:00 - 17:00
  • Timer 5: 17:00 - 21:00
  • Timer 6: 21:00 - 01:00

Activating Timers

A critical point often missed is that simply setting a timer is not enough. To use the timers, you need to activate the corresponding option in the battery settings. For example, if you want to charge from the grid during a timer slot, both Grid charge and Grid signal must be enabled in the battery settings. If these are not activated, "nothing will happen" when the timer slot begins.

The User Timer checkbox must also be checked. If it is not, the batteries will continuously charge from the grid unless the grid supply drops, at which point they will discharge to the shutdown value.

Grid and Sell Features

• Grid Charge: If Grid charge is ticked within a timer slot, the batteries will charge from the grid to the SOC% set for that specific slot. If Grid charge is unticked, the batteries will discharge down to the SOC% set for that time slot.
• Sell Feature: For Classic/Elite single-phase low voltage systems with specific firmware (LCD E43E and MCU2 xx89 or higher), a Sell checkbox is available in the timer settings. If this is checked, the battery will discharge to the set SOC, sending excess power to the grid. This feature requires the system work mode to be 'Zero-Export to CT' (Limit to Home) and 'solar export' to be enabled.
• Combined Sell and Grid: If both Sell and Grid are enabled simultaneously for a timer slot:
• • If the battery SOC is above the timer target SOC, the battery will sell until the target SOC is met.
  • If the battery SOC is below the timer target SOC, the battery will charge until the target SOC is met.
• Sell with low SOC: If the timer is set with Sell checked and the battery is already at or below the target SOC, nothing will happen.
• Power Setting: The Power value in the system timer relates only to the battery buy/sell power. For the combined inverter output power of PV/Wind plus battery power, you must use the Inverter Power Limiter setting. The Max sell power setting defines the maximum number of Watts that will be sent through the grid.

Generator Auto-Start with Timers

Your inverter can also manage a generator's auto-start function, with or without timers:

• Timer disabled: If the system timer is disabled, the generator auto-start will trigger when the battery SOC% falls below Gen Load ON Batt. The batteries will then charge until the SOC% reaches GEN Load OFF Batt.
• Timer enabled: If the system timer is enabled, the generator auto-start will trigger when the battery SOC% falls below Gen Load ON Batt. The batteries will charge until the timer target SOC%, but only during the time periods when GEN charge is ticked. Note that the highest SOC that can be obtained from generator charging is fixed at 95%.

Avoiding Common Pitfalls: Priority Load and 100% SOC Targets

Incorrectly configuring Priority Load can lead to your system not powering your home as expected, especially during timed charging slots.

• Priority Load: If you check the Priority Load box, your solar panels will prioritise supplying power to the 'Load'. If unchecked, solar power will be directed towards charging the batteries first. If Priority Load is selected, the batteries will automatically charge from excess solar once the load has been covered.
• The 100% SOC Trap: A common issue arises if Priority Load is selected and your batteries are set to charge to 100% in a timer slot from the grid or generator. In this scenario, the batteries will remain at 100% until the end of the selected timer. This means that power will not go to the load until the next timer starts, effectively leaving your house without power from the inverter during that period.
• Priority Battery: If Priority Battery is ticked, you must select a time during the day for the battery to be prioritised over the load. For example, setting a time from 12:30 to 16:30 with an SOC of 100% and no Grid or Gen options ticked will cause Priority Battery to charge the batteries to 100% between these times without covering the load, unless solar production is higher than the battery's set charge current. Before and after this set timer, the inverter will revert to prioritising the load.

Essential Battery Settings for Optimal Performance

Beyond the timers, several battery settings directly influence your inverter's behaviour and the health of your battery bank. These are found in the Battery Settings menu.

• Batt Type: This setting is where you select the type of battery. All Sunsynk batteries are lithium.
• Batt Capacity: This value should reflect the total storage capacity of your installed battery bank. For example, if a Sunsynk 5kW battery is 100Ah, two such batteries would mean you insert 200Ah.
• Discharge Amps: This determines the maximum current the battery can discharge to the load. This current is based on DC voltage.
• Charge Amps: This determines the maximum current the battery can charge from the PV array. This current is based on DC voltage.
• Shutdown: This is the State of Charge (SOC) percentage at which the inverter will shut down, and no power will be drawn from the batteries. This value should correspond to your battery's Depth of Discharge (DoD), with a recommended 5% buffer above the minimum DoD.
• Low Batt: The inverter will begin to alarm if the battery SOC% falls below this value. It should be set 5% above the Shutdown value, or can match it.
• Restart: Once the battery SOC% rises above this value, the AC output will resume, and the battery can supply the load. It should be set 10% above Low Batt.
• Activate: This feature helps recover an over-discharged battery by slowly charging it from the solar array or grid.
• BMS_Err_Stop: When active, if the Battery Management System (BMS) fails to communicate with the inverter, the inverter will stop working and report a fault.
• Protocol: This number changes based on the battery you are using and its communication protocol. Most batteries communicating via CAN use protocol 0, while RS485 batteries may vary.
• Grid Charge: This setting must be turned on if you want to charge your batteries from the grid.
• Grid Start: The battery will only begin charging from the grid when its SOC% is above this value. It should be set lower than both Low Batt% and Shutdown%.
• Grid Amps: Similar to Charge Amps, this determines the current at which batteries charge from the grid, based on DC voltage.
• Gen Charge: This setting must be turned on if you want to charge your batteries from a generator connected to the generator terminal.
• Gen Start: The battery will only begin charging from the generator when its SOC% is above this value.
• Gen Amps: Similar to Charge Amps, this determines the current at which batteries charge from the generator, based on DC voltage.
• Gen Force: When enabled, this forces the generator to start without meeting other conditions, overriding SOC conditions.
• Battery Empty V: This is the voltage at which the battery is considered completely flat.
• Signal ISLAND MODE: When checked and the inverter connects to the grid, the ATS port voltage will be 0. When checked and disconnected from the grid, the ATS port will output 230Vac.
• Low Power Mode: With this enabled, if the battery SOC falls below the Low Batt threshold and there is no PV generation, the inverter switches to Low Power Mode. It stops powering non-essential loads and reduces its own quiescent current.
• Low Noise Mode: Enabling this changes the switching speed of the inverter's internal electronics to 20kHz (from a default of 15kHz). This is intended for radio interference, not audible fan or relay noises.
• Disable Float Charge: For lithium batteries with BMS communication, the inverter maintains the charging voltage at the current level when the BMS requests zero charging current, helping to prevent overcharging.

High-Voltage Battery Configurations

For high-voltage inverters, battery configuration impacts discharge current:

• Utilising Bat1 only: This configuration allows a maximum of 50Amps discharge from the battery. The discharge current can only be set to 50Amps.
• Utilising both battery ports and 1 BMS: This setup allows for a full 100Amp discharge. Parallel Bat1&2 must be enabled for this configuration.
• Utilising each port with its own battery: This configuration also allows for a full 100Amp discharge from the connected batteries. Both battery BMS's are connected and can be viewed on the LiBms pages 1&2 on the inverter. Parallel Bat1&Bat2 must not be enabled.

The Grid Trickle Feed and South African Prepaid Meters

The Grid Trickle Feed setting is particularly relevant in South Africa, especially for homes with prepaid electricity meters.

This setting refers to the amount of power flowing from the grid to the inverter. You can set this value to '20 - 100W' to instruct the inverter to consistently draw this set amount of power from the grid. Its primary purpose is to "minimize tripping sensitive pre-paid electricity meters in case 'Reverse Power Detection' occurs." The value "Must not be set under 20W and does not need to be set any higher." This setting also allows for monitoring of the CT coil and enables the inverter to use the trickle feed for its own self-consumption.

What you can change yourself, and what you cannot

As a system owner, you have control over many settings to optimise your Sunsynk inverter's performance. These typically include:

• Work modes: Selecting how your system interacts with the grid and your loads.
• Timer settings: Adjusting start/end times, target SOCs, and enabling/disabling grid or generator charging/discharging within those slots.
• Battery SOC targets: Setting Shutdown, Low Batt, and Restart percentages (within safe limits recommended by your battery manufacturer).
• Priority Load/Battery: Deciding how solar power is prioritised.
• Smart Load settings: Configuring auxiliary load behaviour based on solar production and battery SOC.

However, certain settings are critical for grid stability and safety, and changing them requires the expertise of a registered person. These include:

• Grid protection settings: Any settings related to grid voltage limits, frequency limits, or anti-islanding.
• Export limits: The overall maximum power your system can export to the grid.

In South Africa, work on these settings must be performed by a qualified electrician or solar installer who holds a valid Certificate of Compliance (CoC) for the installation. Unauthorised changes can void your warranty, breach your connection agreement with Eskom or your municipality (which operates under NRS 097-2-1 standards), and create safety hazards. For more information on compliance, refer to our guide on The Electrical Certificate of Compliance for Solar in South Africa.

What the published sources do not tell you

While Sunsynk provides extensive documentation, there are a few points to be aware of:

• South African Grid Codes: The Sunsynk knowledge base often references UK/Ireland grid codes like G98/G99. There is no published Sunsynk guidance for specific South African grid code values (NRS 097-2-1). Sunsynk's grid-settings menu is password-protected, and the documented procedure for unlocking it is written for the UK G98/G99 configuration rather than a South African one. We do not reproduce that password here: grid-protection settings are a registered person's work in South Africa, and altering them can put an installation out of step with its Certificate of Compliance and its connection agreement.
• Menu Paths: The exact menu paths to access specific settings can vary slightly between different firmware versions and inverter models. The documentation describes the settings themselves but does not always provide a step-by-step navigation guide for every scenario.
• 'Sell' Feature Availability: The Sell feature in the timer settings is "firmware-gated," requiring "software version LCD E43E and MCU2 xx89 or higher." If your inverter has older firmware, you may not see this option. Sunsynk does not provide a timeline for firmware updates.