If we are dealing with visible radiation, the number of lumens falling per unit area on a plane surface is called the illuminance , and is expressed in lumens per square metre, or lux. A lumen per square metre is a lux , and a lumen per square cm is a phot. A lumen per square foot is often usually! By submitting the information, you give your consent to the potential publication of your inputs on our website according to our rules. If you later retract your consent, we will delete those inputs.
As your inputs are first reviewed by the author, they may be published with some delay. See also: radiometry , optical intensity , optical power , photometers , radiance , illuminance and other articles in the categories general optics , light detection and characterization , vision, displays and imaging , optical metrology.
If you like this page, please share the link with your friends and colleagues, e. These sharing buttons are implemented in a privacy-friendly way! Sorry, we don't have an article for that keyword! Figure 1: Irradiance is received radiant flux per unit area. Measurement of Optical Irradiance Irradiance values can be measured with suitable photodetectors. Data were collected to populate the conversion chart shown in Table 8.
Lower illumination values were added to the data from Table 6, where, for example, the 0. Data analysis by linear regression, included the error of the ND filter transmission, is used to determine the conversion formula and the uncertainty.
Of interest is, even with the addition of the error from the ND filters, the overall standard deviation is lower because of the addition of more, and less varying, data points. Full range solar simulator: light meter illuminance versus solar simulator irradiance. Table 8. Table 9 presents the coincident natural solar irradiance and illuminance values collected and tabulated. Table 10 presents the results of calculated, laboratory solar simulation, natural solar light, and their respective standard uncertainties.
The indoor laboratory results possibly differ from the outdoor solar measurement because of a difference in the spectra of the incident light.
A change in the spectral power distribution effects the conversion results. This difference is also shown in the results of the calculated lx in the different CIE curves shown in Table 4. Table 9. Light meter illuminance versus pyranometer solar irradiance. Input uncertainty of field measurements, equipment calibration accuracies, and the CIE curves was considered in the development of a reasonable conversion factor. This guide provides a basis for the utilization of a light meter for the measurement of sunlight for the evaluation of PV cells at low irradiance levels.
This conversion works because the solar irradiance data are well understood, standardized, and include set levels at each wavelength. This conversion is not straightforward because the CIE curves are strongly wavelength-dependent, and the widely varying composition of artificial light spectra means a single factor utilizing illuminance measurement is not possible.
A method to utilize illuminance and light source spectral power distribution would enable the evaluation of PV cell performance under low-level artificial and other types of non-solar spectral lighting.
Thomas Missimer. A conversion guide: solar irradiance and lux illuminance Peter R. Michael 1 , Danvers E. Johnston 2 , Wilfrido Moreno 3. Michael, et al. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Copy Bibtex. Copy Ris. Copy APA. Copy Harvard. Copy IEEE. Copy MLA. Copy Vancouver. Copy Chicago. Cite this article. Views Reads Downloads WoS Core Citations 2.
CrossRef Citations 5. Introduction Harvesting of electrical energy using photovoltaic PV systems is an essential part of renewable energy development. Materials and methods 2. Irradiance measurement Irradiance measurement utilizes different technologies, including pyranometers Fig. Solar irradiance measurement devices: a pyranometers and b silicon devices a.
Illuminance measurement Utilizing the unit of lux, light meters provide a measurement of visible light illuminance. Light illuminance measurement devices. A conversion factor would enable the use of light meters to evaluate PV performance under low solar irradiance conditions.
This conversion is a supplement to Luminous Efficacy that compares atmospheric light in units of lumens to solar irradiance in units of watts. A survey of the literature found no definitive and readily available "rule of thumb" conversion standard between solar irradiance and Lux.
Peer-reviewed literature contains Luminous Efficacy equivalents values of 21 to lumens per watt. This analysis explores the relationship and establishes a theoretical and laboratory measurement guide for conversion for solar irradiance and light Lux.
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