I. Zaharie*, I. Luminosu and D. Ignea

Departmental de Fizica, Universitatea “POLITEHNICA” din Timisoara
Bulevardul Vasile Parvan No.2, 300233, Timisoara, Romania7
*Corresponding Author: ioan. zaharie@fiz. upt. ro, izaharie@gmail. com

Abstract

The paper presents a numerical study, using its own the Ray — Tracer software, about optical efficiency, during equinoxes and solstices, of a static paraboloidal concentrator installed on the roof of a building. The roof is inclined with 45 deg and is oriented South.

The optical efficiency is maximum during equinoxes and minimum during solstices.

All these results are in concordance with the results reported in literature illustrating the fact that the proposed software tool is competitive.

Keywords: paraboloid, flow’s density, aperture, optical efficiency

1. Introduction

In the competition between classically obtained electric energy and photovoltaically obtained electric energy, the solar generated energy price is prohibitive because the materials are expensive and the efficiency is low. A solution consists in the concentration of solar light. Though, the using of concentrators that follow the sun is not a realist solution because the installation’s price is high and non-conveniable for users. As a consequence, there are used more cheap static concentrators that are also easy to use [1, 2, 3].

The Ray-Tracer software is using the Ray — Tracing method and is used to study the paraboloidal concentrator. The concentrator is of non-imaging type. The small dimensions paraboloidal concentrators are considered as architectural elements mounted on the houses roofs. The paraboloids walls are made out of very cheap plastic materials covered in void with nanometric film made of aluminium or silver. The reflexion coefficient, R, does not depend on the incidence angle and we consider for R the value, R=0.96. The concentrated radiation falls on the nanostructured photovoltaic cells located in the focal plan of the paraboloid. The efficiency of the photovoltaic cells increases from 14-16 % up to 24 — 30% [4, 5, 6, 7].