Product Overview

The SD400 is a single-phase MPPT hybrid inverter that combines solar power conversion, battery charging, AC charging, energy-source management, and pure sine wave output in one unit.

Rated output options include 3.6kW, 4.2kW, and 6.2kW, with nominal single-phase output selectable at 220V, 230V, or 240V AC. The inverter can accept power from compatible photovoltaic arrays, batteries, utility grids, or generators according to the selected configuration and operating mode.

A dual load output arrangement separates the main output from a second load output. This allows the system designer to assign essential and lower-priority loads to different circuits. The available power on the second output depends on the inverter model and battery operating conditions.

The SD400 also provides MPPT solar charging, configurable AC input ranges, pure sine wave output, RS232 and RS485 communication, and optional WiFi or GPRS connectivity. Battery communication must be matched to the supported lithium battery and BMS protocol.

Dual Load Output

Main Load Output

The main load output is designed to supply the primary connected loads within the rated capacity of the selected SD400 model.

The maximum listed main-load power is:

The continuous load should remain within the inverter rating after accounting for load type, starting current, ambient temperature, battery condition, and operating mode.

Second Load Output

The second output can be used for lower-priority or controlled loads. The published maximum second-load power in battery mode is:

The second output should not be treated as additional power above the total inverter rating. The combined loads must remain within the permitted output capacity and applicable operating conditions.

Load Priority Management

A typical installation may connect critical loads to the main output and less critical loads to the second output.

Potential main loads include:

• Lighting

• Communication equipment

• Refrigerators

• Security systems

• Computers

• Other priority circuits

Potential second-output loads may include:

• Nonessential sockets

• Selected appliances

• Water heating

• Auxiliary equipment

• Loads that can be disconnected at low battery voltage

The final arrangement should be based on the appliance power, startup current, required backup time, battery capacity, and local wiring regulations.

Second-Output Voltage Thresholds

The specification table lists battery-voltage thresholds for disconnecting and reconnecting the second load.

These values suggest different nominal battery-voltage configurations, but the exact 24V or 48V battery requirement must be confirmed for each model.

MPPT Solar Charging

PV Energy Tracking

The SD400 uses an integrated Maximum Power Point Tracking controller to regulate the photovoltaic operating point as sunlight and module temperature change.

The published MPPT voltage range is 60–450VDC, with a nominal DC voltage of 360V and a maximum PV input voltage of 500VDC.

The PV array must be designed so that:

• Cold-weather open-circuit voltage remains below 500VDC

• Normal operating voltage remains inside the MPPT range

• Array current remains within the applicable input-current limit

• Array power does not exceed the permitted input rating

• Isolation and protection meet local electrical requirements

Maximum PV voltage must be calculated using the module temperature coefficient and the lowest expected site temperature.

PV Input Capacity

The listed maximum PV input power is:

PV oversizing can help increase energy production during weak sunlight, but the array voltage, current, power, and inverter limits must all be checked.

The product page also refers to dual PV input and dual MPPT tracking. The exact number of MPPT trackers, string inputs, and current limit per tracker should be confirmed for the selected hardware version.

Solar Charging Current

The specification table lists a maximum solar charging current of 120A, while the feature description refers to a built-in 100A MPPT solar charge controller.

Because these two values differ, the correct maximum charging current should be confirmed for each SD400 model before battery and cable sizing.

Energy Sources and Operating Modes

Solar Power

Photovoltaic power can supply connected loads, charge the battery, or support grid interaction according to the configured operating mode.

Available solar power changes throughout the day. The operating priority should therefore reflect the load requirement, battery capacity, tariff structure, and required backup reserve.

Utility or Generator Input

The SD400 can accept a compatible AC supply from the utility grid or a generator. The listed selectable AC input ranges are 90–280VAC and 170–280VAC.

A wider input range may be suitable for general household loads, while a narrower range may be selected for equipment requiring more stable input conditions. The exact operating logic should follow the manual.

When connecting a generator, check:

• Nominal voltage

• Frequency stability

• Waveform quality

• Continuous power

• Surge capacity

• Neutral and grounding arrangement

• Automatic-start requirements

Off-Grid Operation

In off-grid mode, the inverter can supply loads from solar and battery power, with a compatible AC source available for charging or bypass where configured.

The published battery-mode output is 220/230/240VAC pure sine wave, with stated DC-to-AC efficiency of up to 94%.

Hybrid Operation

Hybrid operation coordinates PV, battery, AC input, load supply, and possible grid output according to the selected priority settings.

Before enabling grid-connected operation, confirm that the supplied SD400 version has the required grid-interface functions, anti-islanding protection, certification, and settings for the installation country.

A general CE declaration does not by itself confirm compliance with every national grid-connection standard.

Battery Operation

Operation With a Battery

A connected battery can store photovoltaic or AC energy for use when solar production is low or the utility supply is unavailable.

Battery selection should consider:

• Nominal battery voltage

• Battery chemistry

• Usable capacity

• Maximum charge current

• Maximum discharge current

• Required backup time

• Cycle-life target

• Installation temperature

• BMS compatibility

The battery current at high load can be substantial. Battery cables, fuses, disconnects, terminals, and busbars must be sized for the actual current and permitted voltage drop.

Operation Without a Battery

The product page states that the inverter can operate without a battery.

Battery-free operation may allow compatible PV and AC sources to supply loads without installed energy storage. However, performance depends on the firmware, operating mode, available solar power, AC source, and connected load.

Without a battery, sudden changes in solar production or load demand cannot be buffered by stored energy. Confirm the supported modes and load limitations before designing a battery-free system.

Lithium Battery Communication

The communication interface list includes lithium battery connectivity. Compatible battery operation may require communication between the inverter and the battery-management system.

Before connecting a lithium battery, confirm:

• Supported battery brand and model

• Communication protocol

• CAN or RS485 interface

• Cable pinout

• Battery voltage

• Charging limits

• Firmware compatibility

• BMS alarm handling

A physically compatible communication connector does not guarantee protocol compatibility.

Lead-Acid Batteries

If lead-acid batteries are supported, charging voltage, float voltage, equalization, low-voltage cut-off, temperature compensation, and battery capacity must be configured for the battery manufacturer’s requirements.

Equalization should not be enabled for a battery chemistry that does not permit it.

Single-Phase Pure Sine Wave Output

The SD400 provides nominal single-phase output at 220V, 230V, or 240V AC.

Pure sine wave output is suitable for many household and office loads, including:

• Lighting

• Refrigerators

• Televisions

• Computers

• Network equipment

• Fans

• Small power tools

• Selected air-conditioning loads

Compatibility still depends on continuous power, surge current, power factor, operating voltage, and waveform sensitivity.

Starting Loads

Compressors, pumps, motors, and transformers may require several times their rated running power during startup. Load selection should therefore consider both continuous and surge demand.

The connected load should not be selected only by adding the nameplate wattage of each appliance.

Output Power Factor

The page lists an output power factor of 1.0 and a grid-output power factor above 0.99. The applicable value and test conditions should be confirmed for the exact operating mode.

Monitoring and Communication

The SD400 communication options include:

• RS232

• RS485

• WiFi

• GPRS

• Lithium battery communication

WiFi or GPRS can support remote operating-data access when the required communication module, application, and network service are installed.

Depending on the ordered configuration, monitoring information may include:

• PV voltage and power

• Battery status

• Load power

• AC input status

• Output voltage

• Operating mode

• Charging status

• Fault records

• Historical energy data

WiFi and GPRS should be described as available or optional until the standard package contents have been confirmed.

Remote monitoring does not replace on-site inspection of batteries, cables, protective devices, ventilation, and electrical connections.

Input and Output Protection

A complete hybrid inverter installation should include coordinated protection for every energy source.

PV-Side Protection

PV protection may include:

• DC isolator

• String overcurrent protection

• DC surge protective device

• Correct-polarity verification

• Protective grounding

• PV-rated connectors and cables

Battery-Side Protection

Battery protection may include:

• DC fuse or circuit breaker

• Manual battery disconnect

• Insulated terminals

• Correct cable size

• Battery enclosure

• BMS protection

• Temperature monitoring

AC-Side Protection

AC protection may include:

• Input circuit breaker

• Output circuit breaker

• Residual-current protection where required

• Surge protection

• Neutral and grounding arrangement

• Generator isolation

• Separate protection for both load outputs

Protection selection should follow the inverter manual and local electrical regulations.

System Design and Selection

Calculate the Load

Prepare a load list showing:

• Appliance

• Quantity

• Running power

• Starting power

• Daily operating hours

• Priority level

• Required backup time

Essential loads should be separated from high-power or nonessential loads when using the dual-output function.

Select the Inverter Rating

Choose the 3.6kW, 4.2kW, or 6.2kW configuration using continuous load, startup demand, expected temperature, operating mode, and required expansion margin.

Size the Battery

Battery energy can be estimated from the required load and backup time:

Battery energy requirement = Load power × Operating time

The calculation should then account for permitted depth of discharge, inverter efficiency, battery aging, temperature, and reserve capacity.

Size the PV Array

PV capacity should reflect:

• Daily energy consumption

• Peak sun hours

• Seasonal irradiance

• Module temperature

• Cable loss

• Charging loss

• Battery charging demand

• Maximum inverter input limits

The array must satisfy both the voltage and current limits of the selected SD400 version.

Separate the Load Outputs

Assign essential loads to the main output. Place suitable lower-priority loads on the second output so that they can be disconnected when the battery reaches the configured threshold.

Do not connect life-safety equipment unless the entire system has been designed and approved for that purpose.

Applications

Residential Solar Systems

The SD400 can coordinate solar generation, battery storage, utility power, and household loads in compatible single-phase residential systems.

Backup Power

Battery storage can support selected critical loads during utility interruptions. Actual backup time depends on battery capacity, battery condition, inverter efficiency, and connected load.

Small Offices

Computers, network equipment, lighting, security systems, and selected office appliances can be divided between the main and secondary load outputs.

Remote Properties

Locations with weak or unavailable grid service can use PV and battery storage, with a compatible generator serving as an additional power source.

Shops and Small Commercial Sites

The system can support selected lighting, communication, refrigeration, security, and point-of-sale loads where their combined continuous and starting demand stays within the inverter rating.

Technical Specifications

Model Comparison

Common Specifications

All parameters should be confirmed against the latest SD400 datasheet and exact model code before ordering.

Quality and Engineering Support

IFIND assembles and tests its inverter products before packing. Technical support is available for:

• SD400 model selection

• PV string calculation

• Battery sizing

• Lithium BMS matching

• Load-output allocation

• AC input configuration

• Generator matching

• WiFi or GPRS setup

• RS232 and RS485 communication

• Fault diagnosis

For system evaluation, customers should submit the load list, appliance starting power, daily energy consumption, PV module specifications, battery information, AC supply data, generator rating, and required backup time.

FAQs

What does dual load output mean?

It means the inverter provides a main load output and a second controlled load output. The second output can be assigned to lower-priority loads and disconnected according to battery conditions. It does not double the inverter’s rated power.

Is dual load output the same as dual MPPT?

No. Dual load output refers to the AC load circuits. Dual MPPT refers to photovoltaic input tracking. They are separate functions.

Can the SD400 operate without a battery?

The product page states that battery-free operation is supported. Confirm the applicable operating modes, PV requirements, AC-source requirements, and load limitations for the selected version.

What battery voltage is required?

The listed second-output thresholds suggest 24V battery systems for the 3.6kW and 4.2kW versions and a 48V system for the 6.2kW version. This must be confirmed from the official model table before ordering.

Does the SD400 support lithium batteries?

The communication table lists lithium battery connectivity. Compatibility depends on the battery voltage, BMS protocol, communication interface, cable pinout, and firmware.

Are WiFi and GPRS included as standard?

The page states that WiFi and GPRS are available. Confirm whether the required module is included or optional, together with the supported application and regional network compatibility.

Can the inverter connect to a generator?

Yes, the product information states that it is compatible with a generator supply. Generator voltage, frequency, waveform, neutral arrangement, continuous power, and surge capacity must be checked.

Can the SD400 feed power into the utility grid?

The page includes grid-tie operating specifications. Before enabling export, confirm the exact model, anti-islanding protection, local grid certification, export-control requirements, and utility approval.

How should the PV string be configured?

The complete string should operate within the 60–450VDC MPPT range, while cold-weather open-circuit voltage must remain below 500VDC. Current and maximum PV power must also remain within the selected model’s limits.

Can the 6.2kW version continuously power a 6.2kW load?

Its listed rated output is 6200W, but practical loading must also consider ambient temperature, startup current, battery discharge limits, PV availability, AC source, operating mode, and manufacturer derating requirements.

What information is needed for model selection?

Provide the continuous and starting load, daily energy use, required backup time, PV module data, battery voltage and capacity, BMS protocol, AC input conditions, generator specifications, and communication requirements.