Abstract
The concentrating photovoltaic (CPV) systems allow good results for generation of clean energy at competitive costs, but a careful selection of the optical system is essential to obtain energy and economic advantages. Hence, three different point-focus optics (parabolic mirror, spherical mirror and a commonly used Fresnel lens) characterized by same dimensions are compared in this paper from energy and economic point of view in order to identify the most convenient in terms of unit cost of electrical power. The optical concentration factor, the maximum values of triple-junction (TJ) cell electrical power and temperature are experimentally measured for each optical system, and successively, the unit cost of electrical power is calculated. The parabolic mirror results the least convenient because it guarantees almost the same performances of a spherical optics but with costs of about 2.7 times higher than it. The Fresnel lens presents a value of the unit cost of electrical power near to the spherical mirror, but its much lower optical efficiency implies a necessary area for the CPV plant about three times larger. Moreover, a forecast of the increase in the CPV plant power capacity in Italy and the consequent decrease in the unit cost of electrical power in two possible scenarios, optimistic and pessimistic, is realized. A reduction of the unit cost of electrical power, between 13 and 30%, is expected for the CPV systems.
Highlights
The energy demand in the world is significantly increasing due to population growth and industrial evolution [1]
Referring to the point-focus optics, in this paper the main technologies used are considered and a comparison from the energy and economic point of view is realized for three different typologies of optics: Fresnel lens, parabolic mirror and spherical mirror
The energy performances of a concentrating photovoltaic (CPV) system depend on the levels of solar concentration that its optical system allows to obtain
Summary
The energy demand in the world is significantly increasing due to population growth and industrial evolution [1]. The photovoltaic–thermal (PV/T) systems can simultaneously produce electrical and thermal energy, decreasing electricity production costs and increasing the overall use of solar energy. An effective way to maximize efficiency levels is to adopt concentrating photovoltaic (CPV) or concentrating photovoltaic and thermal (CPV/T) systems [6] These systems use optical devices such as mirrors or lenses able to convey the solar radiation on smaller multi-junction (MJ) cells and to obtain higher electrical power due to their higher electrical conversion efficiency [7]. CPV and CPV/T systems allow good results at competitive costs for generation of clean energy [10], but a careful selection of the optical system typology and of its concentration factor is fundamental to obtain energy and economic advantages [11]. The principal aim is to evaluate the optical systems most convenient in terms of unit cost of electrical power
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