Isolated PV Panel Circuitry for High-Voltage Series Connection
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Solution Overview
Problem
Photovoltaic panels face challenges with increased system voltage, leading to performance degradation and higher insulation resistance demands, necessitating circuitry that allows for serial connection without increased insulation resistance and lower operating voltage to enhance system longevity.
Innovation Solution
Integration of an isolated converter circuit within photovoltaic panels that converts DC power with adjustable duty cycles, providing galvanic isolation and adjustable voltage outputs, enabling serial connection of panels with reduced voltage ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If photovoltaic panels are connected in series to increase system voltage, then power output capability is improved, but insulation resistance requirements increase and performance degradation occurs
Solution Approach 1:
The photovoltaic panel is divided into multiple independent series strings of cells, with each string connected to its own isolated converter circuit. This segmentation allows each string to operate independently with its own voltage level, enabling the panel to achieve high total voltage output while each individual string maintains lower voltage operation, thus avoiding performance degradation associated with high voltage exposure across the entire panel.
Solution Approach 2:
An isolated converter circuit acts as an intermediary between the photovoltaic cell strings and the external circuitry. This intermediary performs galvanic isolation, allowing voltage transformation and power transfer without direct electrical connection. The isolated converter enables the panel to output high voltage to the grid or load while the internal photovoltaic cells operate at lower, safer voltage levels, preventing insulation breakdown and performance degradation.
2Power
If photovoltaic panels are connected in series to increase system voltage, then power output capability is improved, but insulation resistance requirements increase
Solution Approach 1:
The isolated converter circuit serves as a galvanic isolation barrier between the high-voltage output side and the low-voltage photovoltaic cell side. This intermediary blocks the propagation of high voltage stress to the insulation structures, allowing the panel to deliver high power at high voltage to the load while the insulation only needs to withstand the lower operating voltage of the photovoltaic cells, significantly reducing insulation resistance requirements.
Solution Approach 2:
The isolated converter circuit dynamically transforms voltage parameters between its primary and secondary sides. By changing the voltage level through controlled switching and galvanic isolation, the system allows the photovoltaic panel to operate at low voltage (reducing insulation requirements) while delivering high voltage output (maintaining power capability), effectively decoupling the voltage stress from the insulation structures.
3Power
If photovoltaic panels operate at higher voltages, then power output is improved, but system longevity decreases due to performance degradation
Solution Approach 1:
The panel structure is segmented into multiple independent voltage domains, with each photovoltaic string operating at its optimal low voltage level. This segmentation prevents any single string from being exposed to high voltage stress that would accelerate degradation, while the cumulative effect of multiple strings through the isolated converter achieves the desired high power output, thereby extending system longevity.
Solution Approach 2:
The isolated converter circuit acts as a protective intermediary that shields the photovoltaic cells from high voltage exposure. By performing galvanic isolation and voltage transformation, it allows the panel to deliver high power output without subjecting the photovoltaic cells to high voltage stress, which is a primary cause of performance degradation and reduced longevity. This protects the cells from electrostatic discharge, arc formation, and other high-voltage-related degradation mechanisms.
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
The solution allows for safer and more efficient operation of photovoltaic systems by reducing panel voltage requirements, enhancing system longevity and safety through galvanic isolation and adjustable voltage management.
Implementation Method 1
The isolated converter circuit may include a primary input connected to the input terminals and a secondary output galvanically isolated from the primary input. The isolated converter circuit may convert DC power on the primary input to a DC power on the secondary output.
Data Source
Figure 1
Figure 2a~2b
Figure 3a
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.