Development of FLATCON^® modules using secondary optics

Abstract

In this paper we report on research activities at the Fraunhofer Institute for Solar Energy Systems (ISE) and Concentrix Solar in the area of secondary optics for FLATCON ® modules. This concentrator photovoltaic (CPV) technology is based on Fresnel-lenses as primary optics, passive heat spreaders and triple-junction III-V solar cells. In the first part of the paper, a field performance analysis is presented for Concentrix CPVsystems recently installed in Spain. Subsequently, the performance of the first FLATCON ® modules with reflective and refractive secondaries are evaluated (FLATCON ® II) in indoor and outdoor measurements. As a result of this development, the first module with automated assembly process of the secondary optics could be manufactured. The highest outdoor efficiency measured for this kind of module is 29.1 %, which is the highest module efficiency achieved at the Fraunhofer ISE so far.

Analysis and Prediction of Energy Production in Concentrating Photovoltaic (CPV) Installations

“…Since multi-junction solar cells are very sensitive to the spectrum, a model for EP simulation is presented that takes the spectrum into account [3]. The utilization of secondary optics in a new Concentrix CPV system is explained in the context of the performance of this system [26].…”

High-Concentration Optics for Photovoltaic Applications

“…As one can imagine, tertiary optics are common depending on the design of the optical system, and a wide range of shapes is used. Reflective secondary optics tend to have increased flux uniformity and colour-mixing effects, but dielectric secondariness using TIR can withstand more internal reflections without much loss [42]. Too many reflections in both optics results in severe light ray loss by way of Fresnel losses, not meeting TIR criteria, or in light being reflected back (opposite direction of receiver).…”

“…Merged forms, including the circular-square cone, which has a circular entry merged with a square exit, are possible as well. Square solar cells are more common than circular, and hence square-exit faces are usually desired, but there are plenty of examples of circular cells with circular optics [42,46].…”

Photovoltaic Concentrators - Fundamentals, Applications, Market & Prospective

“…These components require a high level of precision for their assembling in the module; indeed, the higher is the concentration level to ménage, the higher is the precision of positioning, in order to avoid magnified losses; these secondary optics usually have to work under beams already highly concentrated. In high concentration photovoltaic modules, positioning errors higher than 100 microns can produce not negligible power losses (Diaz et al 2005); however, this level of precision is usually achieved by high speed pick & place equipments for SMT in electronics, which are employed for the receivers assembly (Jaus et al, 2009). …”