Analysis and comparison between a concentrating solar and a photovoltaic power plant

• Solar energy is a source, which can be exploited in two main ways to generate power: direct conversion into electric energy using photovoltaic panels and by means of a thermodynamic cycle. In both cases the amount of energy, which can be converted, is changing daily and seasonally, causing a discontinuous electricity production. In order to limit this drawback, concentrated solar power plants (CSP) and photovoltaic plants (PV) can be equipped with a storage system that can be configured not only for covering peak-loads but also for the base-load after the sunset or before the sunrise. In CSP plants it is the sun's thermal energy to be stored, whereas in PV applications it is the electrical energy to be stored in batteries, although this is not economically and environmentally feasible in large-scale power plants.The main aim of this paper is to study the performance of concentrated solar power plants equipped with molten salts thermal storage to cover a base load of 3MWel. In order to verify the possibility of storing effectively the thermal energy and to design a plant for base load operation, two locations were chosen for the study: Gela in southern Italy, and Luxor in Egypt. The electricity production of the CSP facilities has been analyzed and then compared with the electricity production of PV plants. Two different comparisons were done, one by sizing the PV plant to provide the same peak power and one using the same collectors surface. This paper has also highlighted some important issues in site selection and in design criteria for CSP plants used for base load operation.The high variability of the direct normal radiation during the year in southern Italy may cause several problems in CSP facilities, mainly related to the wide range of energy input from the sun. The more uniform and higher values of the solar radiation in the Egyptian location mitigates this problem and allows achieving higher efficiencies than in southern Italy. In most cases the electricity produced by the CSP plant is higher than that produced by a similar PV plant, because the presence of the storage system guarantees the continuity of electricity production even without solar radiation. An economic analysis based on the estimation of the levelized electricity cost (LEC) for both CSP and PV power plants located both in south of Italy and Egypt was carried out in order to investigate which is the most cost effective solution. In all the cases considered, the CSP facilities resulted the best option in terms of cost of electricity produced due to the continuity of energy production during the night hours.

Nyckelord

Base load operation

Concentrating solar power plant

Levelized cost of energy

Performance analysis

Photovoltaic plant

Base load operations

Levelized costs

Economic analysis

Electricity

Heat storage

Photovoltaic cells

Power quality

Site selection

Solar energy

Solar power plants

Solar radiation

Sun

Thermal energy

Thermodynamic properties

Cost benefit analysis

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