Configuring Sunsynk and Deye Smart Load Settings: Auxiliary Port Automation

Key Takeaways

• The Smart Load output allows homeowners to automatically power high-draw appliances such as water heaters using surplus solar energy without draining storage reserves.
• This setting is designed for when you have a good amount of PV production, and your batteries are at a certain SOC; you can activate the smart load to power up an immersion heater for example.
• In South African installations subject to frequent grid interruptions, configuring Off Grid Immediately Off ensures that non-essential loads are severed instantly when load shedding begins.
• A benchmark configuration pairing a 1000W solar generation floor with 80% activation and 50% cutoff prevents contactor cycling during transient cloud cover.
• Always disconnect utility supply breakers and isolate solar DC strings before servicing internal terminal connections.

Understanding the Smart Load Function

Managing electrical demand in a South African residential solar installation requires a delicate balance between maximizing daytime self-consumption and preserving backup reserves for load shedding. High-consumption appliances—most notably domestic geysers, pool filtration pumps, and borehole systems—can rapidly drain a lithium battery bank if allowed to operate unchecked during utility outages.

Traditional residential electrical installations wire these non-essential circuits ahead of the main inverter input on the non-backup section of the main distribution board. While this prevents them from draining the battery when Eskom power fails, it creates a significant operational drawback: those appliances cannot benefit from surplus solar generation during peak midday sun once the home batteries reach full capacity and municipal export restrictions prevent feeding power back into the grid.

The auxiliary terminal block found on Sunsynk and Deye hybrid inverters resolves this dilemma. This hardware connection can be programmed as a dynamically switched auxiliary output. This setting is designed for when you have a good amount of PV production, and your batteries are at a certain SOC; you can activate the smart load to power up an immersion heater for example. By routing dedicated non-essential circuits to this port, the inverter acts as an intelligent energy diverter, switching loads on only when surplus clean energy is available.

For comprehensive scheduling of broader inverter modes, see our guide on Sunsynk system mode and timer settings.

Navigating the Auxiliary Load Menu

Accessing the control menu on both Sunsynk touchscreen units and Deye displays follows a standardized menu architecture:

1. From the home display screen, tap the gear icon in the upper right corner to enter the primary settings interface.
2. Step 1 – From the settings menu, click auxiliary load.
3. Step 2 – Select Aux load output and click save.

```
[Main Settings Screen]
│
▼
[Auxiliary Load Menu]
│
├─► Select: "Aux Load Output" ──► [Click Save]
│
├─► Set: "Solar Power" Threshold (e.g. 1000W)
│
├─► Set: "Aux Load ON Batt" (e.g. 80%)
│
├─► Set: "Aux Load OFF Batt" (e.g. 50%)
│
└─► Toggle: "Off Grid Immediately Off" (Recommended for ZA)
```

Once the auxiliary function is assigned to load diversion rather than microinverter coupling or generator auto-start, the operational threshold parameters become editable.

Key Smart Load Parameters Explained

Configuring the auxiliary output correctly requires setting four core software parameters that dictate exactly when the internal transfer contactor engages and disengages.

Solar Power Threshold

Solar Power – This is the minimum W of solar production for the GEN port to become active (This also requires the Aux load ON batt to be above the set SOC).

This parameter acts as an irradiation gate. If heavy overcast weather restricts generation, the inverter will refuse to energize the auxiliary port even if the battery bank currently holds sufficient energy. This prevents draining stored energy that was captured during earlier sunny intervals or charged from off-peak utility slots.

Aux Load ON Batt Percentage

Aux Load ON Batt – SOC percentage for when the GEN port will start emitting power.

This threshold establishes the minimum battery capacity required before excess energy is shared with high-draw appliances. Setting this threshold high ensures that essential household loads and primary battery charging take unconditional priority during early morning generation hours.

Aux Load OFF Batt Percentage

Aux Load OFF batt – SOC percentage for when the GEN port will stop emitting power.

This cutoff parameter defines the lower boundary of battery engagement. If solar irradiation drops due to passing cloud cover while the auxiliary appliance is actively running, the inverter temporarily draws complementary energy from the battery bank. Once battery capacity declines to this programmed floor, the contactor disengages to protect remaining energy reserves.

For related battery protection settings, review our reference on Sunsynk battery cut-off settings.

Protecting Essential Backup Reserves: Grid Interruption Logic

Under South African operating conditions, managing auxiliary loads during grid outages is critical. Sunsynk and Deye firmware provides two distinct operational toggles governing how the port responds when Eskom or municipal power drops out.

On Grid Always On

On grid always on – This will bypass the above settings and always output power from the GEN terminals whilst grid is connected.

When this option is toggled, the inverter ignores both solar generation and battery percentage parameters whenever the utility grid is energized. The auxiliary terminals behave as a standard grid passthrough feed, continuously supplying connected circuits. While this guarantees uninterrupted service to heavy appliances during normal grid conditions, it eliminates midday solar optimization because the appliance draws from the grid whenever solar generation falls short.

Off Grid Immediately Off

Off grid immediately off – This will stop emitting power from the GEN terminals when the grid is lost.

In South Africa, this toggle should almost universally be enabled. When load shedding strikes, the inverter instantly de-energizes the auxiliary contactor, shedding heavy hot-water cylinders, space heaters, or pool pumps in less than a single AC cycle. This preserves the entire remaining storage capacity exclusively for protected essential sub-distribution board circuits—such as home lighting, refrigeration, communication routers, and home office equipment.

If you observe unintentional grid export while dialing in these parameters, consult our troubleshooting guide on Sunsynk exporting when it should not.

Recommended Setup Example and Hysteresis Logic

To prevent rapid on-and-off cycling of heavy electrical contactors, the firmware incorporates built-in switching hysteresis. Consider the standard reference implementation:

• Example setup Solar power: 1000W Aux Load OFF: 50% Aux Load ON: 80%

With these parameters active:

• With the settings above if the solar generation is below 1000W but the battery is above 80% the GEN port will NOT emit power.
• If the solar generation is above 1000W and the battery is above 80% then the GEN port will emit power and will then turn OFF once the battery SOC reaches 49%.

```
[State 1: Morning Startup]
Solar < 1000W OR Battery < 80% ────────► Smart Load: DE-ENERGIZED
│
▼ (Solar > 1000W AND Battery >= 80%)
[State 2: Peak Solar Production]
Surplus PV Diverted to Auxiliary Load ──► Smart Load: ENERGIZED
│
▼ (Passing Clouds / Evening Settling)
[State 3: Battery Cushioning]
Battery Discharging Slowly ────────────► Smart Load: REMAINS ENERGIZED
│
▼ (Battery Declines to 49%)
[State 4: Protection Cutoff]
Battery Reaches 49% (Below 50% Floor) ──► Smart Load: DE-ENERGIZED INSTANTLY
```

This dynamic hysteresis is vital for equipment longevity. Without the spread between an 80% activation point and a 50% shutdown floor, a transient cloud dropping solar generation would cause the auxiliary contactor to chatter open and closed repeatedly, causing contact pitting and potentially damaging compressor motors or electronic elements.

Platform Compatibility: Sunsynk and Deye Parity

Both Sunsynk and Deye hybrid inverters originate from a shared core hardware architecture developed by Ningbo Deye Inverter Technology. Consequently, the physical auxiliary connection and switching logic are identical across both brands. Deye commercial and residential datasheets explicitly specify full hardware support for the Smart Load function across their single-phase and three-phase hybrid inverter families.

Whether an installer is commissioning a Sunsynk touch-panel interface or a Deye unit running standard firmware, the menu terminology, operational logic, and protection thresholds function identically.

Electrical Safety and Sub-Distribution Wiring

Wiring heavy residential appliances to an inverter auxiliary port introduces specific installation and safety requirements under South African national electrical regulations.

• Upstream Electrical Isolation: Prior to opening the inverter wiring cover or manipulating terminals on the auxiliary block, an installer must isolate the main AC supply breaker at the distribution board and disconnect all DC isolators from the photovoltaic array. High DC voltages from solar strings present severe arc flash and lethal shock risks.
• Dedicated Protective Switchgear: The auxiliary port outputs AC power through internal switching relays. Cables exiting the auxiliary terminals must terminate into a dedicated sub-distribution enclosure containing appropriately sized miniature circuit breakers and residual current devices before reaching appliance isolating switches.
• Neutral and Earth Integrity: Inverters operating off-grid must maintain correct earth-neutral bonding across all sub-circuits. Ensure that the neutral conductor of the smart load sub-board is correctly routed according to South African national wiring regulations and never cross-connected with non-inverter neutrals.

Operational Troubleshooting

When properly programmed, the Smart Load feature transforms a standard hybrid inverter into an automated home energy manager, maximizing free solar utilization while guaranteeing uninterrupted power security during South African load shedding.