An innovative method for determining the junction temperature of a photovoltaic cell
13 May 2012-pp 1847-1850
TL;DR: In this article, the junction temperature T J as a function of the cell voltage V of a photovoltaic (PV) cell for varying operating power levels at pre-determined values of irradiation levels is presented.
Abstract: An innovative method for determining the junction temperature T J as a function of the cell voltage V of a photovoltaic (PV) cell for varying operating power levels at pre-determined values of irradiation levels is presented. Since the junction of a PV cell that is in operation is inaccessible for obtaining a measure of T J , a novel indirect temperature measurement method suitable for determining the T J is proposed in this paper. The electronically controllable load required to establish different operating power levels for obtaining the T J - V characteristic of a photovoltaic (PV) cell is implemented with a MOSFET, suitably controlled to act as a variable load resistor. Microcontroller based hardware with associated software were developed to automate the entire measurement process. Results obtained from a prototype T J - V measurement unit built and tested establish the efficacy of the proposed method.
Citations
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TL;DR: In this article, the authors proposed silicon solar cell-integrated stress and temperature sensors for in situ measurement of solar cells within photovoltaic (PV) modules, which can be used in research for increased measurement accuracy of the temperature and the mechanical stress in PV modules.
Abstract: We propose silicon solar cell–integrated stress and temperature sensors as a new approach for the stress and temperature measurement in photovoltaic (PV) modules. The solar cell–integrated sensors enable a direct and continuous in situ measurement of mechanical stress and temperature of solar cells within PV modules. In this work, we present a proof of concept for stress and temperature sensors on a silicon solar cell wafer. Both sensors were tested in a conventional PV module setup. For the stress sensor, a sensitivity of (−47.41 ± 0.14)%/GPa has been reached, and for the temperature sensor, a sensitivity of (3.557 ± 0.008) × 10$^{-3}$ K$^{-1}$ has been reached. These sensors can already be used in research for increased measurement accuracy of the temperature and the mechanical stress in PV modules because of the implementation at the precise location of the solar cells within a laminate stack, for process evaluation, in‐situ measurements in reliability tests, and the correlation with real exposure to climates.
8 citations
Cites methods from "An innovative method for determinin..."
...Also, the silicon solar cell itself is used as a temperature sensing device by utilizing the temperature dependency of the voltage.(23) However, since the voltage depends on various factors, the operation conditions, especially the irradiation, need to be determined as well....
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01 Nov 2015
TL;DR: This paper presents an inductive pressure sensor which can be employed for the acquisition of biomedical signal, and these signals can be extremely vital in monitoring and diagnosing human body conditions.
Abstract: This paper presents an inductive pressure sensor which can be employed for the acquisition of biomedical signal, and these signals can be extremely vital in monitoring and diagnosing human body conditions Based on the nature of the application, such implementations require precise and real time measurement for measuring any biomedical parameters The proposed inductive pressure sensor is based on the basic principle of producing inductive changes in response to the movement of a core towards a coil Using the inductive coil, the physical parameter that is the movement of iron core is translated into a signal with proportionate output frequency change This type of sensor offers some important criteria like high level of linearity and sensitivity The proposed pressure sensor can be very effective as it can be used in many biomedical applications
5 citations
01 Jan 2012
TL;DR: In this paper, the authors presented a novel approach of an inductive sensor based on the basic principle of producing inductive changes in proportion to sea saw oscillations of a horizontal bar.
Abstract: This paper presents a novel approach of an inductive sensor based on the basic principle of producing inductive changes in proportion to sea saw oscillations of a horizontal bar. The circuit is supported by resistances and capacitances meant for deriving a signal from implantable devices. Basically, it's a pressure sensor which can be used for the acquisition of medical signal, and is very helpful in diagnostic procedures. Using an inductive coil sensor working on a differential manner, a physical parameter is translated into a signal with proportionate output frequency change. The results shown can be used for characterizing the materials and hence sensor with high sensitivity, linearity and responsiveness in harsh environmental condition. Key word: Inductance-to-frequency converter, variable inductance, magnetization, pressure sensor, displacement, relative permeability.
3 citations
15 Jun 2015
TL;DR: This paper presents an inductive pressure sensor which can be employed for the acquisition of biomedical signal, and these signals can be extremely vital in monitoring and diagnosing human body conditions.
Abstract: This This paper presents an inductive pressure sensor which can be employed for the acquisition of biomedical signal, and these signals can be extremely vital in monitoring and diagnosing human body conditions. Based on the nature of the application, such implementations require precise and real time measurement for measuring any biomedical parameters. The proposed inductive pressure sensor is based on the basic principle of producing inductive changes in response to the movement of a core towards a coil. Using the inductive coil, the physical parameter that is the movement of iron core is translated into a signal with proportionate output frequency change. This type of sensor offers some important criteria like high level of linearity and sensitivity. The proposed pressure sensor can be very effective as it can be used in many biomedical applications.
2 citations
06 May 2013
TL;DR: A novel temperature sensor suitable for continuous monitoring of the health of a solar photovoltaic (PV) panel that powers an earth bound satellite is presented, which replaces the platinum resistance temperature (PRT or SPRT) probes used in a conventional solar panel temperature measurement system.
Abstract: A novel temperature sensor suitable for continuous monitoring of the health of a solar photovoltaic (PV) panel that powers an earth bound satellite is presented in this work. The method proposed here employs one of the photovoltaic cells of the panel itself as the sensor for measuring the solar panel's temperature. In order to make the sensor work even when the panel is not receiving sunlight, that PV cell being used as a temperature sensor is lit with a white light emitting diode. The novel temperature sensor thus realized, replaces the platinum resistance temperature (PRT or SPRT) probes used in a conventional solar panel temperature measurement system. Results obtained from a prototype temperature measurement unit built and tested establish the efficacy of the proposed method. It is clearly established that the proffered method is capable of reliable measurement of a solar panel's temperature in the range -150°C to +150°C.
2 citations
Cites background from "An innovative method for determinin..."
...In [5], it is pointed out that Voc is dependent apart from the temperature of the PV cell on the illumination impinging on the cell as well....
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...The linear variation of Voc as a function of PV cell’s temperature over a limited temperature range (from 20 °C to 80 °C) has been reported [5]....
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References
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01 Nov 1997
TL;DR: Effective methods for determining temperature coefficients for cells, modules and arrays are described; sources of systematic errors in measurements are identified; typical measured values for modules are given; and guidance for their application in system engineering is provided.
Abstract: The term "temperature coefficient" has been applied to several different photovoltaic performance parameters, including voltage, current and power. The procedures for measuring the coefficient(s) for modules and arrays are not yet standardized and systematic influences are common in the test methods used to measure them. There are also misconceptions regarding their application. Yet, temperature coefficients, however obtained, play an important role in PV power system design and sizing, where often the worst case operating condition dictates the array size. This paper: describes effective methods for determining temperature coefficients for cells, modules and arrays; identifies sources of systematic errors in measurements; gives typical measured values for modules; and provides guidance for their application in system engineering.
309 citations
"An innovative method for determinin..." refers methods in this paper
...Hence alternate methods were proposed to determine the PV cell’s junction temperature from the measured values of the cell’s open circuit voltage (VOC) and the temperature co-efficient of VOC [1] - [4]....
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TL;DR: In this paper, a simple formulation has been derived for the temperature dependence of cell parameters for any solar cell material, and detailed calculations have been performed for high-quality monocrystalline GaAs, Si and Ge cells.
Abstract: A simple formulation has been derived for the temperature dependence of cell parameters for any solar cell material. Detailed calculations have been performed for high-quality monocrystalline GaAs, Si and Ge cells. Preliminary experimental data for GaAs and Si cells are close to the calculated values. In general, the higher the energy gap of a material, the small is the temperature dependence of its solar cell parameters.
219 citations
"An innovative method for determinin..." refers methods in this paper
...The opamp drives the gate of the MOSFET and maintains the voltage at its non-inverting terminal to be equal to the voltage at its inverting terminal provided vD VOC where VOC is the open circuit voltage of the PV cell under test....
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...The junction temperature versus VOC of polycrystalline silicon PV cell is found to be linear and the linear fit is also shown in Fig....
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...Thus the opamp forces the terminal voltage VP of the PV cell under test to follow the output of the DAC, vD as long as vD VOC....
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...V and P-V characteristics, the I-V and VOC characteristics can also be plotted as shown in Fig....
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...Using equation (2), the junction temperature Tj is computed for every step from the measured values of VOC....
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01 Jan 2003
TL;DR: In this article, a comparative study of four methods for extracting solar cell parameters of the single diode lumped circuit model is presented, which are usually the saturation current, the series resistance, the ideality factor, the shunt conductance and the photocurrent.
Abstract: This paper presents a comparative study of four methods for extracting solar cell parameters of the single diode lumped circuit model. These parameters are usually the saturation current, the series resistance, the ideality factor, the shunt conductance and the photocurrent. The methods are the vertical optimisation method, the analytical five-point method, and two methods we have proposed and based on the current voltage characteristics and the subsequently calculated conductance. Parameter values were extracted using these different methods from experimental I-V characteristic s of a commercial solar cell and a module.
63 citations
08 Aug 2005
TL;DR: In this article, a new methodology to determine the I-V and P-V curves of photovoltaic modules by using DC-DC converters is proposed, which allows carrying out the complete sweep of the voltage and the current (including V/sub oc/ and I/sub sc/).
Abstract: The achievement of I-V and P-V curves of photovoltaic modules gives the possibility of obtaining their characteristic parameters: the short-circuit current (I/sub sc/), the open-circuit voltage (V/sub oc/), the maximum power point (MPP) and the fill factor (FF). These values are significant for the design of a photovoltaic system. These curves depend on the global irradiance (G), the temperature (T) and the spectral distribution of the solar irradiation. In this paper, a new methodology to determine the afore mentioned curves by using DC-DC converters is proposed. This methodology allows carrying out the complete sweep of the voltage and the current (including V/sub oc/ and I/sub sc/). Regarding the traditional methods, this new one provides the following advantages: a) minimum power loss with regard to the systems that operate in lineal zone (active zone); this implies several advantages in size and cost; and b) this new method allows an automatic adaptation of the interpolation interval.
54 citations
07 Jun 2009
TL;DR: In this article, the authors proposed a method to improve the prediction of electrical energy yield especially for PV modules based on thin-film technologies by measuring the nominal operation cell temperature (NOCT).
Abstract: Aim of this study is to improve the prediction of electrical energy yield especially for PV modules based on thin film technologies. Problems with deficient power prediction of PV power plants have manifold reasons: One of the easy accessible is the measurement of NOCT (nominal operation cell temperature). Deviations of NOCTs measured have a direct influence of the yield predicted (1–5%). The deviations due to different measurement methods and different temperature sensors have been discussed in theory (systematic error) and have been investigated in laboratory tests as well as under real world conditions in an outdoor lab. The thermal behavior is studied and the measurement results are compared to theoretical models. As a result the theoretical yield as a function of the measured NOCT is compared for different installation sites and for different technologies.
41 citations