System, apparatus and method for efficient use of solar photovoltaic energy
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Solution Overview
Problem
Solar photovoltaic (PV) energy systems face challenges in efficiently delivering energy to water heaters due to fluctuations in solar input, leading to inefficiencies and electromagnetic interference issues, particularly at low insolation levels and with existing DC-based systems.
Innovation Solution
A control system and method that prioritize energy delivery from a solar PV source to a water heating system, utilizing multiple switchable heating elements and a modulator to manage energy flow, converting DC to AC, and optimizing energy usage by switching heating elements in parallel to maximize energy consumption from the PV source before drawing from the utility grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If DC current is used to power the heating unit from the solar collector, then the system can operate at low insolation levels, but it is difficult to interrupt the DC current and connector contacts can be eroded by sparks on switching
Solution Approach 1:
The patent replaces the mechanical DC switching system with an AC switching system. The solar collector output is converted to AC power through an inverter, allowing the use of AC switches (contactors or relays) that are designed to handle AC current interruption. This substitution maintains the ability to operate at low insolation levels while solving the contact erosion problem inherent in DC switching.
2Productivity
If solar PV energy is delivered to the utility grid, then feed in tariff benefits are maximized, but the opportunity to replace household power consumption is reduced
Solution Approach 1:
The patent implements a dynamic control system that monitors solar PV output, household consumption, and grid conditions in real-time. The system dynamically adjusts the distribution of solar energy between self-consumption (water heating) and grid feed-in based on current conditions. This allows the system to maximize self-consumption when solar output exceeds household demand, thereby reducing reliance on grid power and maximizing the value of solar energy to the household.
3Device complexity
If a single heating unit is used in electric storage water heaters, then the system is simple, but energy efficiency is limited especially at low insolation levels
Solution Approach 1:
The patent divides the single heating unit into multiple independent heating elements (first heating element and second heating element). These segmented elements can be independently controlled and switched based on available solar energy levels. At high insolation levels, both elements operate to maximize heating capacity. At low insolation levels, the system can selectively activate only the necessary elements, improving overall energy efficiency while maintaining system simplicity through modular design.
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 enhances energy efficiency by ensuring continuous energy delivery to water heaters even at low insolation levels, reduces electromagnetic interference, and adapts existing systems to prioritize internal energy consumption, thereby optimizing the use of solar PV energy.
Implementation Method 1
solar photovoltaic (PV) collector to produce DC energy
Implementation Method 2
use the electrical energy to heat a resistive heating unit in the tank
Data Source
AI summary
A solar photovoltaic (PV) water heating system includes a tank including at least a first heating unit having at least first and second heating elements, at least one of which is switchable; a PV solar collector; an inverter adapted to convert the output from the PV collector to an alternating power supply; a modulator to modulate the alternating power supply from the inverter; a controller adapted to control the modulator and the switching of the or each switchable heating element; wherein the controller is adapted to control the modulator and the switchable heating elements to maximize the energy drawn from the PV collector.