Solar Inverter Communication Structure via LAN and Serial Interfaces

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Solution Overview

Problem

Existing solar inverter communication systems are inefficient and prone to failure due to reliance on thin, fragile cabling for network connections, limiting accessibility and flexibility in decentralized photovoltaic installations, and lack individual inverter control capabilities.

Innovation Solution

A communication structure where solar inverters are connected via LAN interfaces for efficient web access and serial interfaces using robust two-wire lines, with some inverters acting as communication masters and others as slaves, allowing for decentralized data access and control, and incorporating a standby master for redundancy and a router for linking multiple installations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If each solar inverter is connected via separate communication units to the communication network, then individual inverter control and data access are enabled, but cabling complexity and installation cost increase due to requiring thin network cables or telephone lines for each inverter

Engineering Contradiction:

Improveindividual inverter controlVSAvoidcabling complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

Multiple inverters are connected in series via a single serial communication bus, merging multiple individual connections into one shared communication path. This eliminates the need for separate network cables to each inverter, reducing cabling complexity while maintaining individual control capability through addressable communication protocols

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A master inverter acts as an intermediary between the communication network and slave inverters. The master receives commands from the network and relays them to specific slave inverters via the serial bus, enabling individual control without requiring direct network connections to each inverter

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If thin network cables or telephone lines are used for connecting inverters to the communication network, then direct network access is achieved, but the cables are fragile and require careful handling during installation

Engineering Contradiction:

Improvenetwork access capabilityVSAvoidcable durability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system uses robust serial communication interfaces (RS-232, RS-485) that can tolerate harsher installation conditions and physical stress compared to thin Ethernet cables. These serial cables are more durable and easier to install in difficult-to-reach locations, sacrificing some network protocol sophistication for physical robustness

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Speed

If Ethernet connections are used for inverter communication, then high-speed data transmission is achieved, but the cable length is restricted without corresponding repeaters

Engineering Contradiction:

Improvedata transmission speedVSAvoidcable length

Core Design Contradiction:

SpeedVSLength of stationary object

Solution Approach 1:

The system dynamically selects between different communication modes: high-speed Ethernet for short-distance connections where performance is critical, and serial communication for long-distance connections where cable length exceeds Ethernet limitations. This dynamic adaptation allows the system to optimize for either speed or distance based on installation requirements

Inventive Principle:

Principle #15Dynamics

4Device complexity

If a central communication facility is used to connect all solar inverters, then network infrastructure is simplified, but the entire installation fails if the control center malfunctions

Engineering Contradiction:

Improvenetwork infrastructureVSAvoidsystem availability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The communication network is segmented into independent zones where each inverter (or group of inverters) can operate autonomously. If one inverter or communication segment fails, others continue to function independently, eliminating the single point of failure inherent in centralized control architectures

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system incorporates redundant communication paths and failover mechanisms. If the primary communication path fails, alternative routes are automatically activated, cushioning against the impact of communication failures and maintaining system availability

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS7899035B2Communication structure for solar inverters

Publication Date: 2011.03.01 SMA SOLAR TECH AG

AI summary

There is described a communication structure for at least two solar inverters, having a transmission medium by means of which each of the at least two solar inverters is connected to a communication network with a first group of the solar inverters each being connected via an LAN interface to the communication network, and with a further group of the solar inverters being connected to the first group via serial interfaces. Two different network types are therefore provided with the first being suitable for standard LAN technologies with rapid data transmission over short distances, and with the second being suitable for interference-insensitive data transmission over long distances.