Isolated Photovoltaic Panel Circuitry for Lower-Voltage Solar Strings
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Solution Overview
Problem
Increased maximum system voltage poses a burden on photovoltaic manufacturers to provide higher insulation resistance, and high voltage at elevated temperatures in humid climates leads to performance degradation of photovoltaic modules.
Innovation Solution
Integration of an isolated converter circuit with a photovoltaic panel, allowing for galvanic isolation between the panel and the output, enabling more panels to be wired serially without increasing insulation resistance and allowing for lower operating voltage operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If more photovoltaic panels are wired serially to increase system voltage, then power output is improved, but insulation resistance requirements increase and performance degradation occurs
Solution Approach 1:
The patent divides the high-voltage serial string into multiple isolated converter modules, each handling a portion of the total voltage. Each module contains its own isolated DC-DC converter that galvanically isolates the panel input from the output, segmenting the voltage stress and insulation requirements across multiple independent units rather than requiring one panel to handle the entire system voltage.
Solution Approach 2:
The isolated converter circuit acts as an intermediary between the photovoltaic panel and the electrical load. The converter galvanically isolates the panel from the output circuitry, allowing voltage transformation and electrical isolation that protects the panel from high-voltage stress while maintaining power transfer efficiency.
2Reliability
If higher insulation resistance is provided to support increased system voltage, then safety is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The insulation requirement is segmented across multiple isolated converter modules rather than requiring a single panel to provide high insulation resistance for the entire system voltage. Each converter module only needs to provide insulation for its portion of the voltage, significantly reducing the insulation resistance burden on individual panels.
Solution Approach 2:
The isolated converter serves as an intermediary that assumes the insulation responsibility, allowing the photovoltaic panel itself to maintain standard insulation specifications. The converter's galvanic isolation provides the required electrical separation without modifying panel manufacturing.
3Reliability
If photovoltaic panels operate at lower voltages to reduce insulation burden, then insulation requirements are reduced, but power output decreases
Solution Approach 1:
The isolated DC-DC converters transform the voltage parameter between input and output. Panels can operate at their optimal lower voltage for reduced insulation requirements, while the converters step up or step down voltages as needed to maintain system power output and match load requirements.
Solution Approach 2:
Power output is segmented across multiple parallel converter modules. While each individual panel operates at lower voltage, the aggregate power from multiple panels processed through multiple converters maintains or exceeds the power output of traditional high-voltage serial configurations.
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 allows for increased long-term lifetime of photovoltaic systems by reducing the voltage rating of serially connected panels and maintaining efficient operation at lower voltages.
Implementation Method 1
an isolated converter circuit with a primary input connected to the photovoltaic panel and a secondary output galvanically isolated from the primary input
Data Source
AI summary
A photovoltaic module is presented, which may include a photovoltaic panel and a converter circuit having a primary input connected to the photovoltaic panel and a secondary output galvanically isolated from the primary input. The primary input may be connectible to multiple input terminals within a junction box and at least one of the input terminals may be electrically connected to a ground. The photovoltaic module may include multiple interconnected photovoltaic cells connected electrically to multiple connectors (for example bus-bars). The photovoltaic module may include input terminals operable for connecting to the connectors and an isolated converter circuit. The isolated converter circuit may include a primary input connected to the input terminals and a secondary output galvanically isolated from the primary input.