Solar String Management Units for MPPT Optimization
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Solution Overview
Problem
Traditional maximum power point tracking (MPPT) algorithms in solar arrays fail to optimize energy production due to differences in installation, fabrication, or degradation among solar modules, leading to suboptimal performance as they treat the entire solar array as a single module, which can result in weaker modules affecting the overall energy output.
Innovation Solution
The system employs local management units (LMUs) and local string management units (LSMUs) to individually manage and balance the voltage and current of each string within the solar array, allowing for the selection of a target voltage and the use of removable modular units with bypass, measurement, and voltage conversion capabilities to optimize energy production by connecting multiple strings with modular units that can be easily inserted or removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional MPPT algorithms treat the solar array as a single module, then the control system is simple, but energy production is suboptimal due to weaker modules affecting overall output
Solution Approach 1:
The solar array is segmented into multiple independent strings, each equipped with its own local management unit (LMU) that can independently track maximum power point. This segmentation allows each string to operate optimally without being constrained by weaker modules in other strings, thereby improving overall energy production while maintaining manageable control complexity through modular architecture
Solution Approach 2:
Each local management unit is designed with specialized functionality to manage its specific string's characteristics, including voltage matching circuits and bypass capabilities. This local quality approach allows each LMU to optimize its string's performance based on local conditions while contributing to the overall array output, resolving the contradiction between improved productivity and controlled complexity
2Productivity
If solar modules operate at different working points on the I-V curve due to installation, fabrication, or degradation differences, then individual module performance varies, but traditional MPPT cannot find the maximum power point for the entire array
Solution Approach 1:
The array is divided into multiple strings with independent local management units, allowing each LMU to find and maintain the maximum power point for its specific string based on local module characteristics. This segmentation enables optimization of each string's working points despite variations in installation, fabrication, or degradation
Solution Approach 2:
Local management units serve as intermediary devices between individual solar modules and the central inverter. Each LMU includes voltage matching circuits and control logic that mediate the differences in module working points, converting variable string outputs to a standardized format that the inverter can process, thereby enabling MPP optimization without requiring complex centralized control
3Productivity
If removable modular units with voltage conversion capabilities are used to balance string voltages, then energy production is enhanced, but the device complexity and initial cost increase
Solution Approach 1:
The local management units are designed as universal modular components that can be applied to any string in the array, performing multiple functions including voltage matching, maximum power point tracking, and bypass operations. This universality allows the same modular design to enhance energy harvesting across the entire array without requiring different complex solutions for each string
Solution Approach 2:
The modular units include voltage conversion capabilities that dynamically adjust voltage parameters to match between strings of different configurations. By changing voltage parameters through controlled conversion rather than physical restructuring, the system enhances energy harvesting while keeping the modular unit design relatively simple and standardized
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 energy production by balancing the output of individual solar modules and strings, allowing for improved energy harvesting and simplifying the management of solar arrays by enabling the identification and adjustment of weak modules, thereby maximizing the overall power output of the solar array.
Implementation Method 1
The LSMU can include a voltage conversion portion connected to the input and configured to convert the input voltage to a target voltage for the parallel bus
Data Source
AI summary
Apparatuses, systems and methods for configuring and managing the combination of strings of photovoltaic energy generators to improve the energy production performance of such generators. The strings of photovoltaic energy generators are connected to terminals in a combiner box having receptacles for receiving removable modular units of various types. Removable modular units with measurement capabilities are used in the combiner boxes to measure the direct current input provided by the strings; and in light of the measurements, the removable modular units can be selectively downgraded to simpler units that do not have measurement capabilities to reduce cost, and/or selectively upgraded to more sophisticated units that can adjust the output of the respective strings, such as upconverting the output voltage of the respective strings, to improve the performance of the strings.