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The Inverse Lambertian Irradiation Method: An Optical Tool for PV Solar Concentrators and Urban Heat Islands Characterization
A. Parretta, M. Tucci
Building Integration, Modelling / Modeling, Characterisation, Characterization, Optical Properties, Concentrators
PV Applications, Integration and Storage
Subtopic: PV on/in Buildings
Event: 38th European Photovoltaic Solar Energy Conference and Exhibition
Session: 6CV.4.1
1515 - 1520
ISBN: 3-936338-78-7
Paper DOI: 10.4229/EUPVSEC20212021-6CV.4.1
0,00 EUR
Document(s): paper


The Inverse Lambertian Irradiation Method (ILIM) was developed to get the angle-resolved optical efficiency of a PV solar concentrator quickly and with a relatively simple apparatus. ILIM reverses the path of rays (reverse mode), replacing the PV receiver by a Lambertian light source and projecting the light emitted from the inlet aperture onto a far screen. When ILIM is simulated, the reverse light is projected on an absorbing hemispherical screen in order to get the map of emitted radiance. This map reproduces, apart from a constant factor, that of the optical efficiency of the concentrator operating in direct mode under collimated light. The idea behind the present work is to apply the ILIM to an urban heat island model, to get the collection efficiency of solar radiation of a receiver (a PV or thermal module, a window, etc.) in presence of a strong optical interaction with the urban environment. The receiver is then transformed into a Lambertian source and the light diffused, after the interaction with the surrounding environment (the ground, the buildings walls, any green elements, etc.), is projected onto the absorbing hemispherical dome. The absorbed irradiance, once transformed into a map of radiance, gives the map of collection efficiency. This map, when associated with the path of Sun, gives the actual power (or luminous flux) collected by the receiver, once the incident irradiance (or illuminance) as a function of the Sun position is known.