PV Production Control via Net Load Thresholds
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Solution Overview
Problem
In regions with energy export restrictions, solar photovoltaic (PV) systems face challenges in maximizing energy production while avoiding the export of excess energy to the grid, as utility regulations limit or prohibit feeding energy back into the grid, necessitating real-time adjustments to prevent violations.
Innovation Solution
An asymmetric control method using lower and upper thresholds for monitoring net load, allowing PV generation to be adjusted dynamically, with PV production turned off when net load falls below the lower threshold and maximized when above the upper threshold, and incremental increases in PV generation and controllable loads like smart water heaters or batteries when net load is between thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PV production is maximized to make economic sense, then energy output increases, but risk of violating export restrictions increases
Solution Approach 1:
The system dynamically adjusts PV production based on real-time net load conditions. When net load is high, PV production is maximized; when net load approaches zero, PV production is reduced or curtailed. This dynamic control allows the system to maximize energy output while maintaining compliance with export restrictions that prohibit or limit feeding energy back into the grid.
Solution Approach 2:
The system continuously monitors net load (gross electric load minus PV generation) and uses this feedback to control PV production. The controller compares actual net load against threshold values and adjusts PV output accordingly, creating a closed-loop control system that ensures compliance with export restrictions while maximizing usable energy production.
2Reliability
If PV production is limited to site loads to avoid exporting energy, then export restrictions are complied with, but PV production is reduced
Solution Approach 1:
The system allows PV production to occasionally exceed immediate site load requirements by using controllable loads (such as water heaters or air conditioners) to absorb excess energy. This partial action approach enables the system to operate at higher production levels more frequently while still preventing grid exports through coordinated load management.
Solution Approach 2:
The system uses controllable loads that can serve both their primary function (heating, cooling) and a secondary function of absorbing excess PV energy. This multi-functionality allows the system to maximize PV production without violating export restrictions, as the controllable loads provide an additional pathway for energy utilization beyond just site loads.
3Reliability
If real-time adjustments are made to PV production, then export restrictions are avoided, but system complexity increases
Solution Approach 1:
The control system is segmented into distinct functional components: a monitor that measures net load, a controller that processes the measurements and determines control actions, and actuators that implement the control decisions. This segmentation simplifies the overall system design and makes it easier to implement and maintain while achieving real-time compliance with export restrictions.
4Productivity
If net load monitoring with thresholds is used, then PV production can be optimized, but measurement precision requirements increase
Solution Approach 1:
The system establishes predetermined threshold values for net load before operation begins. These thresholds are set to account for potential measurement uncertainties and fluctuations. By having these thresholds pre-established, the system can make robust control decisions without requiring extremely high measurement precision, as the thresholds provide a buffer against measurement errors.
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 maximizes usable PV power at the site without violating export restrictions, even with noisy meter readings or fluctuations, ensuring minimal energy is exported to the grid.
Implementation Method 1
Solar photovoltaic (PV) systems, in particular, have been very popular EG systems
Data Source
AI summary
A method for controlling photovoltaic (PV) production and storage at a site is disclosed. The method includes monitoring a gross electric load and an actual PV output of the site over time and determining a net load at the site during a time period. The net load is then compared with a lower threshold and an upper threshold to determine a target PV output and a load of a controllable storage load such that the PV production and the controllable storage load at the site can be controlled accordingly to maximize the PV production while limiting or prohibiting feeding energy back to a utility grid.