Solar Module Bypass Switch Circuit Reduces Reverse Voltage Damage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solar module protective circuits experience significant power loss and reliability issues due to reverse voltage problems during shading conditions, which can lead to irreversible damage from excessive reverse voltage across shaded cells.
Innovation Solution
A controllable electrical switch element, such as a MOSFET, is used in parallel with solar cells, controlled by a supply circuit that activates the bypass element during shading, minimizing power loss and ensuring reliability by blocking voltage in normal operation and connecting it during shading conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bypass diodes are connected in parallel to each individual solar cell to protect against reverse voltage, then cell protection is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent groups multiple solar cells (typically 18-24 cells) into subgroups, with each subgroup protected by a single bypass diode. This segmentation approach reduces the number of bypass diodes needed from one per cell to one per subgroup, significantly simplifying the circuit while maintaining protection effectiveness.
Solution Approach 2:
The bypass diode serves multiple functions: it protects shaded cells from reverse voltage damage, provides a current path during partial shading conditions, and prevents hot carrier generation. This multi-functionality reduces the need for additional protective components.
2Reliability
If bypass diodes are used to protect shaded cells, then reverse voltage protection is improved, but power loss increases due to voltage drop across the diode
Solution Approach 1:
The patent uses a controllable switch element (such as a MOSFET) that can dynamically change its state based on operating conditions. During normal operation, the switch remains non-conducting to minimize power loss. During shading conditions, the switch becomes conducting to provide a low-impedance bypass path, reducing both reverse voltage and power loss compared to conventional diodes.
Solution Approach 2:
The switch element's electrical parameters (resistance, conductance) are changed based on control signals. The control electrode voltage is adjusted to transition the switch between conducting and non-conducting states, optimizing the balance between protection and power loss minimization.
3Device complexity
If the number of cells per subgroup is increased to reduce the number of bypass diodes, then device complexity is reduced, but reverse voltage protection effectiveness decreases
Solution Approach 1:
The controllable switch element can rapidly respond to shading conditions and activate to provide a low-impedance path. This dynamic response allows for larger subgroup sizes (more cells per subgroup) while maintaining effective reverse voltage protection, because the switch can quickly prevent voltage buildup when shading occurs.
Solution Approach 2:
The patent employs a robust switch element design that can handle high voltage and current stress during shading events. The switch is designed to withstand the extreme conditions briefly during shading without damage, allowing for larger subgroup configurations with fewer switches while maintaining reliability.
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 reduces power loss and enhances reliability by effectively managing short-circuit currents and reverse voltages, preventing damage to solar cells and improving the longevity of the solar module.
Implementation Method 1
a controllable, electrical switch element, in particular a MOS field effect transistor, whose current path can be connected in parallel to the multitude of solar cells
Implementation Method 2
the body diode which is inherently present in the MOSFET can briefly completely assume the solar generator current
Implementation Method 3
a transformer with a positive feedback winding and a first electronic switch element
Implementation Method 4
an energy storer, into which a transducer transformer can transmit the necessary energy, in particular in a single clock pulse
Data Source
AI summary
A circuit breaker for a solar module, wherein a plurality of solar cells working in normal operation and when shaded are connected in series. At least one controlled electrical switch element serves as a bypass element and is connected in parallel with its contact gap to a plurality of solar cells. A supply circuit provides a control voltage for controlling the control electrode of the bypass element. An isolating circuit blocks the voltage applied to the contact gap of the bypass element in the normal operation and switches the voltage that is applied to the contact gap to the supply circuit when at least one solar cell is shaded.