Solar Cell UV Sensor for Water Disinfection Monitoring
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Solution Overview
Problem
The widespread adoption of solar water disinfection technologies in developing regions is hindered by the lack of affordable sensors to determine when treated water is safe for consumption, as existing sensors are either too expensive or unsuitable for natural sunlight conditions.
Innovation Solution
A low-cost clean water sensor utilizing photovoltaic solar cells to measure global irradiance, cell temperature, and UV irradiance, with a UV-blocking filter to differentiate the UV component, enabling the determination of sunshine duration and water temperature, thereby assessing the effectiveness of solar disinfection processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial UV sensors are used for monitoring solar disinfection, then measurement precision is improved, but cost increases making them unaffordable for developing countries
Solution Approach 1:
The patent replaces expensive commercial UV sensors with inexpensive photovoltaic solar cells that can be discarded after use. The solar cells are used as single-use sensors to measure cumulative UV irradiance, eliminating the need for costly reusable commercial sensors while maintaining measurement capability for the specific application of solar water disinfection monitoring.
Solution Approach 2:
The patent uses photovoltaic solar cells as a substitute copy for commercial UV sensors. Instead of using the original expensive sensor design, it creates an alternative measurement system using readily available solar cells with appropriate filters, achieving similar functional results at a fraction of the cost.
2Measurement precision
If artificial UV disinfection sensors are used, then UV monitoring capability is improved, but adaptability to natural sunlight conditions deteriorates
Solution Approach 1:
The patent modifies the spectral response of the photovoltaic solar cell by adding wavelength-selective filters that are tailored to the specific UVA range relevant for solar water disinfection. This local modification of the sensor's spectral sensitivity allows it to accurately measure the specific UV band needed for disinfection while filtering out other wavelengths, making it adaptable to natural sunlight conditions.
Solution Approach 2:
The patent changes the operational parameters of the photovoltaic cell by using it in photovoltaic mode to measure cumulative irradiance rather than in photothermal mode for concentration measurement. It also introduces wavelength filtering to match the natural sunlight spectrum, transforming the sensor's characteristics to suit outdoor solar disinfection applications.
3Loss of information
If multiple sensors are used to monitor all disinfection parameters, then measurement completeness is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated system. A single photovoltaic solar cell with wavelength-selective filters simultaneously measures cumulative UV irradiance, global irradiance, and by extension can infer sunshine duration and water temperature effects, eliminating the need for multiple separate sensors and reducing system complexity.
Solution Approach 2:
The photovoltaic solar cell serves multiple functions: it acts as a UV irradiance sensor, a global irradiance sensor, and a reference for temperature effects. This multi-functional approach allows one component to provide information for multiple disinfection parameters, reducing the overall number of components needed in the system.
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 sensor provides accurate and affordable monitoring of essential parameters for solar disinfection, ensuring safe drinking water by measuring global irradiance, UV irradiance, sunshine duration, and water temperature, thereby enhancing the usability of solar disinfection technologies in developing countries.
Implementation Method 1
A first sensor unit is provided, comprising at least two photovoltaic solar cells
Implementation Method 2
one of the cells comprising a UV-blocking filter on top
Data Source
Figure 1
Figure 2
Figure 3(a)~3(d)
AI summary
A new low-cost clean water sensor based on photovoltaic solar cells has been developed for addressing one of the problems related to the low reliability of solar water technologies in developing countries: the lack of sensors detecting when the water is safe to drink. The new design is capable of measuring the main parameters that are relevant to solar disinfection: global irradiance, sunshine duration, UV irradiance and water temperature. One of the key aspects of the design is the UV irradiance measurement. Two identical cells were used, one of them with a low-cost UV-blocking filter on top, so the total UV irradiance could be calculated as the difference between the two solar cells output. The first cell would be measuring UV-VIS-NIR and the second only VIS-NIR. The UV filter material was explored and a low-cost architectural film was selected. Initial materials costs for the first prototype was of approximately 4€, excluding labour.