Shade Mitigation Using Secondary Photovoltaic Cell Control
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Solution Overview
Problem
Conventional shade mitigation systems for photovoltaic systems are inefficient, introducing parasitic loads and requiring manual monitoring, and limit systems to string arrangements, leading to reduced power output and issues like fade effects and back-feed.
Innovation Solution
The implementation of a relay switch and a secondary photovoltaic cell that selectively disconnects shaded portions of the system from the rest, using the secondary cell to monitor illumination and control the relay switch to maintain optimal operation of unshaded areas, allowing daisy-chaining and reducing parasitic loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional blocking diodes and bypass diodes are used for shade mitigation, then the system can prevent reverse current flow, but the system introduces parasitic loads and reduces power output
Solution Approach 1:
The patent replaces conventional mechanical/electrical diodes with a photovoltaic-based electronic control system. A secondary photovoltaic cell monitors illumination levels and controls a solid-state switch (MOSFET or IGBT) to disconnect shaded primary photovoltaic cells. This substitution eliminates the parasitic voltage drops inherent in diode-based systems while maintaining reliable shade mitigation through active electronic control.
Solution Approach 2:
The system uses a secondary photovoltaic cell to automatically detect shade conditions and control the switching mechanism without external intervention. The secondary cell generates the control signal based on its own illumination level, creating a self-regulating system that eliminates the need for external power sources or complex control circuits, thereby reducing parasitic loads.
2Reliability
If conventional diode-based shade mitigation systems are used, then the system can protect against reverse current, but manual monitoring is required and the system cannot daisy-chain
Solution Approach 1:
The system implements automatic feedback control where the secondary photovoltaic cell continuously monitors its own illumination level and provides real-time feedback to the solid-state switch. When the secondary cell detects shade (illumination below threshold), it automatically triggers the switch to disconnect the primary cell. This closed-loop feedback system eliminates manual monitoring while maintaining reliable reverse current protection through automated decision-making based on actual shade conditions.
3Device complexity
If string arrangements are used instead of daisy-chaining, then the system is simpler to implement, but power output is reduced
Solution Approach 1:
The patent enables daisy-chaining by implementing independent control for each photovoltaic cell through individual secondary cells and solid-state switches. This segmentation allows each cell to operate autonomously based on its own shade conditions, enabling parallel connection configurations that maximize power output while maintaining system simplicity through modular, repeatable units that can be easily expanded.
4Stability of the object's composition
If shaded portions remain electrically connected to maintain circuit continuity, then the system maintains electrical integrity, but the shaded portion reduces current generation and drags down the entire system
Solution Approach 1:
The system extracts or removes shaded photovoltaic cells from the electrical circuit using solid-state switches that can rapidly open to disconnect affected cells. This extraction maintains electrical integrity of the remaining healthy cells while eliminating the parasitic effect of shaded cells that would otherwise drag down the entire system's current generation through series connection constraints.
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 enables photovoltaic systems to operate closer to full potential by selectively disconnecting shaded areas without manual intervention, reducing energy inefficiencies and eliminating fade and back-feed issues, thereby enhancing power output.
Implementation Method 1
The secondary photovoltaic cell is electrically coupled to the relay switch and is mounted in a position to monitor illumination on the primary photovoltaic cell. The secondary photovoltaic cell energizes the relay switch to selectively complete the circuit between the primary photovoltaic cell and the load when the secondary photovoltaic cell is illuminated by at least a threshold illumination.
Implementation Method 2
The relay switch selectively completes a circuit between the primary photovoltaic cell and the load when energized.
Data Source
AI summary
Shade mitigation systems and devices to mitigate adverse effects of shade on a primary photovoltaic cell powering a load via an output terminal. The shade mitigation devices include a relay switch and a secondary photovoltaic cell. The relay switch selectively completes a circuit between the primary photovoltaic cell and the load when energized. The secondary photovoltaic cell is electrically coupled to the relay switch and is mounted in a position to monitor illumination on the primary photovoltaic cell. The secondary photovoltaic cell energizes the relay switch to selectively complete the circuit between the primary photovoltaic cell and the load when the secondary photovoltaic cell is illuminated by at least a threshold illumination. The secondary photovoltaic cell stops energizing the relay switch to selectively open the circuit between the primary photovoltaic cell and the load when the secondary photovoltaic cell is shaded sufficiently to illuminate it below the threshold illumination.