PV Substring Arrangement for Shading Mismatch Mitigation
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Solution Overview
Problem
Current photovoltaic (PV) modules face efficiency losses and potential damage due to mismatch conditions caused by partial shading, where shaded PV cells reduce the entire substring's output and can lead to 'hot-spots' from excess energy absorption.
Innovation Solution
The solution involves static reconfiguration of PV cell arrays with substrings connected in parallel, series-parallel, or cross-tied configurations, using conductive backsheets and rear contact PV cells to mitigate mismatch conditions and improve efficiency, while also incorporating power electronics for optimized performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If PV cells are connected in series to provide useful electric potential and current output, then the power output is improved, but the system becomes vulnerable to mismatch conditions when shaded cells reduce current production
Solution Approach 1:
The PV array is segmented into multiple substrings that are connected in parallel rather than series. Each substring contains PV cells arranged in series, but the parallel connection of substrings allows independent current paths. When shading affects one substring, other substrings continue to produce current without being constrained by the shaded cells' reduced current output.
Solution Approach 2:
The patent transitions from a single-dimensional series connection to a two-dimensional series-parallel configuration. This dimensional change creates multiple current pathways, allowing the system to maintain power output even when some cells are shaded, as current can flow through alternative parallel paths formed by other substrings.
2Power
If shaded PV cells are forward biased by productive cells in series connection, then the entire string produces useful power, but the shaded cells absorb excess energy causing hot-spots and potential damage
Solution Approach 1:
By segmenting the array into parallel-connected substrings, the patent isolates shaded cells within their own substring. This prevents forward biasing of shaded cells by productive cells from other substrings, as each substring operates independently. The harmful hot-spot effect is contained to at most one substring rather than affecting the entire array.
Solution Approach 2:
The patent extracts shaded substrings from the main power-producing network by connecting substrings in parallel. This allows the system to take out or bypass substrings experiencing shading conditions, preventing them from absorbing excess energy that would cause hot-spots, while maintaining overall power production from unshaded substrings.
3Temperature
If multiple PV cells are connected in series to overcome partial shading, then the electric potential is maintained, but the current production is reduced by the weakest cell
Solution Approach 1:
The patent divides the PV system into multiple substrings connected in parallel, where each substring maintains series connection for adequate voltage. This segmentation allows each substring to operate at its own current level based on its conditions, with the overall system current being the sum of currents from all parallel substrings, thereby overcoming the limitation of the weakest cell.
Solution Approach 2:
The patent changes the electrical connection parameters from pure series to series-parallel configuration. This parameter change allows the system to maintain the voltage benefits of series connection while achieving current additivity through parallel connection, transforming the system's electrical characteristics to optimize both potential and current production.
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 approach enhances PV module efficiency, reduces the impact of partial shading, and minimizes the risk of damage from 'hot-spots' by distributing shading effects and optimizing energy production.
Implementation Method 1
multiple PV cells are connected serially in a string to provide a useful electric potential and current output from the string
Implementation Method 2
using conductive backsheets and rear contact PV cells to mitigate mismatch conditions and improve efficiency
Data Source
AI summary
Aspects of the disclosure relate to static configurations and arrangement of substrings of photovoltaic (PV) cell arrays or PV modules to electrically parallelly connect and spatially distribute substrings in PV cell arrays mitigating the partial shade and/or mismatch condition and decrease complexity of PV module production. Further aspects relate to substrings of serially electrically connected PV cells that may be electrically connected in parallel and arranged such that conductor intersection is minimized or substantially eliminated outside of a junction box. Further aspects of the disclosure relate to utilizing rear contact PV cells and conductive backsheets to effectuate electrically parallel connected and spatially distributed substrings.