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SMA•Sunny Boy Storage 6701

Analysis by Marcus & Team

SMA Sunny Boy Storage 6701 Battery Communication Loss

Troubleshoot SMA Sunny Boy Storage 6701 communication errors with battery. Expert diagnostics for residential hybrid inverter systems.

Frequently Asked Questions

•What tools are needed to test the CAN bus resistance?

A calibrated multimeter capable of reading low resistances accurately.

•Where can I find the latest firmware for my SMA Sunny Boy Storage 6701?

Visit the SMA website or contact your solar installer for firmware updates.

•How often should I perform a battery capacity test?

Battery capacity tests should be performed annually, or as recommended by the battery manufacturer.

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Marcus leads the technical research department at Storage Faults. Together with a team of systems analysts, he specializes in translating complex solar storage error codes into actionable diagnostic steps for the US market.

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Technical Overview:

The Sunny Boy Storage 6701 is a hybrid inverter that manages power flow between solar panels, battery storage, and the grid. Communication between the inverter and battery bank is typically achieved via CAN bus or similar protocol. This communication link transmits vital battery parameters: voltage, current, SOC, SOH, and temperature. Loss of communication prevents the inverter from properly managing battery charging/discharging, leading to system faults and potential damage. Proper AC coupling and anti-islanding protection are reliant on accurate battery data.

Symptoms:

The SMA Sunny Boy Storage 6701 displays a 'Communication Loss' error related to the battery bank. The system may fail to charge/discharge the battery, report incorrect SOC, or shut down entirely. The SMA Energy app might show a disconnected battery, or display erroneous data.

Safety Warning:

Hybrid inverters operate with high DC voltages (up to 600V or higher). Improper handling can result in serious injury or death. Always disconnect all power sources before performing any maintenance or troubleshooting. Follow NEC rapid shutdown procedures and wear appropriate personal protective equipment (PPE), including insulated gloves and eye protection. A qualified electrician is required for any work involving live circuits or internal inverter components.

Solution:

1

*Safety First**: Disconnect AC power to the inverter using the main breaker. Engage the DC disconnect switch for the solar array and battery. Verify voltage is zero using a calibrated multimeter.
2

*Inspect Cables**: Thoroughly inspect all communication cables between the inverter and battery for damage, loose connections, or corrosion. Use a contact cleaner on connectors.
3

*CAN Bus Termination**: Measure the resistance across the CAN bus lines (with the system powered down). A reading close to 60Ω (for a standard 120Ω termination resistor setup) is expected. If the reading is significantly different, check for faulty or missing terminator resistors. Refer to the battery and inverter manuals for the correct termination resistance value and location.
4

*Battery BMS Check**: Consult the battery manufacturer's documentation to diagnose the BMS. Some BMS units have diagnostic LEDs or a service port. Check for error codes or abnormal voltage readings.
5

*Firmware Update**: Ensure both the inverter and battery BMS are running the latest compatible firmware versions. Outdated firmware can cause communication issues.
6

*Inverter Reset**: Perform a factory reset of the inverter, following the manufacturer's instructions. This can clear any corrupted data or software glitches.
7

*licensed technician inspection**: If the problem persists, contact a qualified solar installer or SMA service technician for further diagnosis and repair. They have specialized tools and expertise to diagnose complex inverter and battery issues. All work must comply with NEC 2017/2020 rapid shutdown requirements and local electrical codes.

Possible Causes:

Loose or damaged communication cables between the inverter and battery.
Faulty CAN bus terminator resistors (typically 120Ω).
Battery Management System (BMS) failure within the battery bank.
Inverter firmware incompatibility with the battery BMS.
Inverter communication port failure.
Software glitch or corrupted data on the battery or inverter.

Preventative Care:

Regularly inspect all cables and connections for damage or corrosion.
Keep the inverter and battery firmware up to date.
Monitor battery performance and SOC regularly using the SMA Energy app.
Perform periodic battery capacity tests to assess SOH. Record data for future comparison.
Calibrate the BMS according to the battery manufacturer's recommendations.