Solar Panel Sub-Panel MPPT Control for Shading Loss
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Solution Overview
Problem
Solar power collection panels face significant power reduction due to partial shading, as MPPT control schemes are inefficient when dealing with multiple series-connected photovoltaic (PV) cells, leading to diminished accuracy and increased cost with the need for multiple high-accuracy sensors and circuits.
Innovation Solution
Dividing the solar panel into sub-panels with each sub-panel having a power converter and a common MPPT controller that adjusts output voltages to maximize power delivery, connecting the outputs of these converters in series to a load, allowing for equal voltage control across all converters to optimize power harvesting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If MPPT control is applied to a single long string of series-connected PV cells, then device complexity is reduced, but measurement precision and power harvesting accuracy deteriorate due to shading effects
Solution Approach 1:
The solar panel array is divided into multiple parallel strings of PV cells, with each string having its own power converter and controller. This segmentation allows independent MPPT control for each string, maintaining high measurement precision and power harvesting accuracy even when some cells are shaded, while distributing the device complexity across multiple simpler units rather than one complex system.
2Measurement precision
If multiple high-accuracy sensors and circuits are used to improve power harvesting accuracy under shading conditions, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
Instead of using multiple high-accuracy sensors on a single long string, the system segments the array into multiple parallel strings, each with its own simpler power converter and controller. This distributes the sensing requirements across multiple independent units, maintaining overall measurement precision while reducing the complexity and cost associated with any single sensing system.
Solution Approach 2:
Multiple parallel strings with identical or similar power converter designs are merged at the output to combine their power contributions. This merging approach allows the system to achieve high power harvesting accuracy through the collective output of multiple simpler units rather than relying on a single complex high-precision system.
3Productivity
If the solar panel is divided into multiple shorter strings with individual MPPT control, then power harvesting accuracy improves under shading, but device complexity and cost increase due to multiple sensors and circuits
Solution Approach 1:
The solar panel array is segmented into multiple parallel strings of PV cells, with each string equipped with its own power converter and controller for independent MPPT operation. This segmentation enables the system to maintain high power harvesting efficiency under shading conditions by allowing unaffected strings to operate at full capacity while shaded strings operate at reduced capacity, without requiring an excessive increase in device complexity.
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 substantially reduces the impact of shading on power output, achieving a near-maximum power harvest with a significant cost reduction by using fewer and less complex high-speed circuits, while maintaining high efficiency.
Implementation Method 1
The voltage and current that are developed by a PV cell are a function of the light flux incident on the cell
Data Source
AI summary
Approximately one-half of the loss of delivered power from a solar panel having photovoltaic (PV) cells connected in series to form sub-panels due to shading is recovered at low hardware cost by connecting sub-panels in series and providing maximum power point tracking control in common for the series connected sub-panels such that the respective sub-panels produce equal voltages even in the presence of shading of a portion of one or more sub-panels. By doing so, the input voltage of respective power converters which control the voltage at which each sub-panel is operated can be placed close to the maximum power point of each sub-panel regardless of shading and maximum total power harvested even though the respective sub-panels are not operated at optimum voltages.