Solving the Generation Failure Problem of Soyosource Grid-Tie Inverters

Introduction

This article examines an effective solution to a common problem of generation failures that occurs in Soyosource grid-tie inverters and similar models when input power is exceeded.

The Problem

Soyosource grid-tie inverters have a particular characteristic: when the input power from solar panels exceeds their capacity, they go into protection mode and periodically restart. This leads to unstable system operation - the inverter generates for a few seconds, then goes into protection mode, restarts, and the cycle repeats.

This problem is especially relevant in conditions such as:

• Cold, sunny weather
• When using bifacial solar panels
• When snow cover enhances reflection
• During peak solar hours

Technical Solution

A hardware-software solution has been developed that allows limiting the inverter’s input power without interfering with its circuitry. The solution is based on intercepting and modifying data transmitted between the limiter and the inverter via the RS-485 protocol.

Required Components:

1. Arduino Nano
2. Two RS-485 to TTL converters
3. Optional: display for showing parameters (not required for operation)
4. 5V power supply

Operating Principle

The system intercepts data from the limiter, analyzes it, and if necessary, modifies the power values before sending them to the inverter. The algorithm works as follows:

1. Receiving data from the limiter via RS-485
2. Analyzing the data packet (8 bytes):
   • First 4 bytes - service information
   • 5th and 6th bytes - power data
   • 7th byte - constant
   • 8th byte - checksum
3. When the power threshold is exceeded (for example, 2320W for two inverters), the values in the 5th and 6th bytes are replaced with a safe value (for example, 1160W per inverter)
4. Transmitting the modified data to the inverter

Advantages of the Solution

1. Does not require interference with the inverter’s circuitry
2. Fully reversible - can return to the original configuration
3. Allows precise setting of the desired power limitation
4. Ensures stable operation even with significant excess of input power from solar panels
5. Maintains the equipment warranty

Setup and Operation

The suggested limitation value is 1160W per inverter, considering the device’s own consumption of about 100W. This ensures stable operation without overloading components.

Various limitation thresholds can be set in the program:

• For increased longevity, a lower threshold can be set (e.g., 1000W)
• For maximum performance - increase to rated values
• Settings are customized for each system

Conclusion

This solution effectively resolves the generation failure problem of Soyosource grid-tie inverters and similar models, ensuring their stable operation even in conditions of increased solar activity. The solution does not require complex equipment modifications and can be easily implemented in existing systems.