Performance Evaluation of a High Solar Fraction CPC-Collector System

Abstract

One of the most important goals on solar collector development is to increase the system's annual performance without increasing overproduction. The studied collector is formed by a compound parabolic reflector which decreases the collector optical efficiency during the summer period. Hence, it is possible to increase the collector area and thus, the annual solar fraction, without increasing the overproduction. Collector measurements were fed into a validated TRNSYS collector model which estimates the solar fraction of the concentrating system and also that of a traditional flat plate collector, both for domestic hot water production. The system design approach aims to maximise the collector area until an annual overproduction limit is reached. This is defined by a new deterioration factor that takes into account the hours and the collector temperature during stagnation periods. Then, the highest solar fraction achieved by both systems was determined. The results show that, at 50° tilt in Lund, Sweden, the concentrating system achieves 71% solar fraction using 17 m 2 of collector area compared to 66% solar fraction and 7 m 2 of a flat plate collector system. Thus, it is possible to install 2.4 times more collector area and achieve a higher solar fraction using the load adapted collector. However, the summer optical efficiency reduction was proven to be too abrupt. If the reflector geometry is properly design, the load adapted collector can be a competitive solution in the market if produced in an economical way.

Measurements of the Electrical Incidence Angle Modifiers of an Asymmetrical Photovoltaic/Thermal Compound Parabolic Concentrating-Collector

“…As can be seen from the same figure the front side is less affected by the shading. The IAM t shown in Figure 9 is in agreement with previous measurements for the thermal production of a solar thermal collector with the same geometry [2]. The PV/T hybrid collector is made of two different parts.…”

“…Hence, the optical efficiency of the collector changes throughout the year depending on the projected solar altitude. The tilt of the collector determines the amount of total annual irradiation kept within the acceptance interval [2]. The glass cover of the collector is made of low iron glass with solar transmittance of 0.9 at normal incidence angle.…”

“…The evaluation of the PVT hybrid collector was only performed for the electrical part. The thermal part was previously evaluated in [2] and further measurements are ongoing.…”

Effect of Reflector Geometry in the Annual Received Radiation of Low Concentration Photovoltaic Systems

“…The PVT Solarus collector belongs to the compound parabolic collector (CPC) type, which is commonly known as the maximum reflector concentrator (MaReCo) family [9], and it is widely described in the literature [10][11][12]. It is formed by a reflector with two asymmetrical truncated parabolic sections separated by a circular section (compound parabolic concentrator, CPC), a flat receiver with solar cells in both sides and bi-facial absorbers.…”

“…For energy calculations in the receiver ray tracing software (Soltrace, Tonatiuh) are often used. A detailed description of the adopted procedure for asymmetric Solarus collectors (Tonatiuh) can be found in [9]. In this paper, Soltrace software was used.…”