Inverter AC Interface for Decentralized PV Module Integration

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Solution Overview

Problem

Conventional photovoltaic inverters face limitations in scalability, efficiency, and cost-effectiveness, particularly when dealing with non-homogeneous radiation and mixed PV module types, as they require identical modules and are sensitive to shadowing, restricting the use of different technologies and leading to high costs for advanced module-oriented inverters.

Innovation Solution

An inverter design that integrates an AC interface, allowing decentralized AC modules to connect and share grid functions with a basic inverter, reducing costs and enabling module-by-module MPP tracking, grid compatibility, and communication, while allowing the use of various PV technologies and optimizing energy production in non-homogeneously illuminated areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional PV inverters are used, then grid monitoring functions, safety functions, and MPP tracking are provided, but the system has restricted scalability and cannot accommodate modules of different types

Engineering Contradiction:

ImproveAbility to use different PV module types and technologiesVSAvoidInverter functionality integration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system is divided into two functional segments: decentralized AC modules that perform only basic inversion and MPP tracking, and a centralized basic inverter that provides grid monitoring, safety functions, and reactive power control. This segmentation allows each component to be optimized for its specific function, enabling use of different PV module types while maintaining system simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The basic inverter is designed with universal functionality to handle outputs from multiple different types of PV modules and AC modules. It provides grid monitoring, safety functions, and reactive power control for the entire system, making it compatible with various PV technologies including thin-film and monocrystalline cells.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If module-oriented inverters with additional functions are integrated in AC modules, then MPP tracking and grid compatibility are achieved, but the specific price is considerably higher and efficiency cannot reach conventional PV inverter levels

Engineering Contradiction:

ImproveModule-by-module MPP tracking capabilityVSAvoidSpecific price and manufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The system separates MPP tracking functionality into simple, dedicated AC modules that operate independently for each PV module, while centralized grid monitoring and safety functions are provided by the basic inverter. This segmentation reduces the complexity and cost of each AC module while maintaining individual MPP tracking capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each AC module is designed to autonomously perform MPP tracking for its associated PV module without requiring complex centralized control. The modules self-regulate their operation to maximize power extraction, simplifying their internal design and reducing manufacturing costs.

Inventive Principle:

Principle #25Self-service

3Productivity

If identical PV modules are used in series or parallel circuits, then conventional inverter operation is maintained, but the system cannot optimize power extraction when incident radiation is not homogeneous

Engineering Contradiction:

ImprovePower extraction efficiency under non-homogeneous radiationVSAvoidSystem configuration flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The PV system is segmented into individual PV modules, each with its own dedicated AC module that performs independent MPP tracking. This allows each module to operate at its optimal operating point regardless of radiation conditions, enabling the system to maximize power extraction even when incident radiation is non-homogeneous due to partial shadowing or different module orientations.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enhances scalability, reduces costs, and improves energy efficiency by allowing the use of different PV technologies and optimizing energy production in non-homogeneously illuminated areas, making PV installations more cost-effective and flexible.

Implementation Method 1

an inverter bridge (21) for converting a DC voltage to a first AC voltage

Methodology Applied

Scientific EffectElectromagnetic switching: Electromagnetic Induction

Data Source

PatentEP2612433B1Inverter with an ac interface for the connection of ac modules

Publication Date: 2018.10.10 SMA SOLAR TECH AG

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AI summary

An inverter (20) for feeding a grid-compatible AC voltage into a grid (40) is described, wherein the inverter comprises an inverter bridge (21) for converting a DC voltage to a first AC voltage and a grid interface (30) between the inverter bridge (21) and the grid (40) for converting the first AC voltage to the grid-compatible AC voltage for feeding into the grid (40). An AC interface (60) via which an AC module (50) for feeding into the grid (40) can be connected, is arranged between the inverter bridge (21) and the grid interface (30).