Marco Rosa-Clot

Field Experience With Performances Evaluation of a Single-Crystalline Photovoltaic Panel in an Underwater Environment

In this paper, the electrical and thermal performances of a single-crystalline submerged photovoltaic (PV) solar panel (SP2) is investigated. In particular, due to the presence of water, several phenomena occur such as the modification of solar-radiation spectrum and the reduction of the module operating temperature. These phenomena have different impacts on the global energy performance of the PV module, which depends on the environmental conditions, on the PV technology, and on the water depth. Energy performances of an SP2 module are measured using two different experimental setups in different environmental conditions, with an increase in power ranging from 10% to 15%.

A Path Integral Approach to Derivative Security Pricing: II. Numerical Methods

We discuss two numerical techniques, based on the path integral approach described in a previous paper, for solving the stochastic equations underlying the financial markets: the path integral Monte Carlo, and the path integral deterministic evaluation. In particular, we apply the latter to some specific financial problems: the pricing of a European option, a zero-coupon bond, a caplet, an American option, and a Bermudan swaption.

Floating tracking cooling concentrating (FTCC) systems

The photovoltaic technology is limited by costs, by the availability of spaces for photovoltaic fields and by the storage problems. The solution suggested in this work is the use of artificial basins or small lakes for installing PV floating plants with the following characteristics: a tracking system around the vertical axis, a panels cooling system achieved with water sprinklers and a set of reflectors that, by concentrating the radiation, increase the energy harvesting. We call these plants FTCC, the acronym of Floating, Tracking, Cooling, Concentrating. Additional benefits are possible using hydroelectric basins in particular when they are equipped, as often happens, with pumping facilities. In these structures, the existing pumping devices allow to store the energy produced by the FTCC avoiding energy dispersion problems and the electric grid stress. Three FTCC system solutions are presented and discussed theoretically and experimental results are also discussed. They are characterized by different levels of geometrical concentration, Cg: <;1.5, ≈2 and ≈20. In particular the first two systems use flat reflectors, whereas the third one uses parabolic mirrors. An important issue that arises when these systems are designed and operated is the uniformity of irradiance on the PV surface. This can be reached by means of an effective sensing and tracking of the system taking into account the relative position of sun and reflectors, as well as the acceptance angle of the concentrators. A first plant of 200 kWp based on these concepts is completed and grid connected in Suvereto - Livorno (Li Italy); another 30 kWp pilot plant has been built nearby Pisa (Italy).

Storage Systems and Floating Plants

The realization of storage systems which are both large and cheap allows us to have readily available energy at any time and appears to be the only solution that will make intermittent renewable energies truly competitive with fossil energies. After a general analysis of storage systems we focus our analysis on gravity energy storage (GES) and compressed air energy storage (CAES) systems. Traditional GES, which is widely applied in hydroelectric plants, is extended to sea and ocean environments, and its coupling with floating and submerged photovoltaic (PV) plants is discussed. With regard to CAES, the possibility of using the pipes necessary for the buoyancy of modular raft structures as a compressed air reservoir opens up interesting possibilities. In particular, the huge thermal inertia of basins allows an isothermal compression-expansion cycle, which promises high storage efficiency. Furthermore, hybrid systems which mix water pumping and air compression are analyzed and proposed as the optimal solution for PV plants on water.

Floating Plants and Environmental Aspects

The problem of land occupancy is discussed and the advantages and potentiality of floating plants are outlined. The geographic potential and compact factor concepts are discussed. The problem of evaporation in wastewater basins and water reservoirs is analyzed with emphasis on the effect of floating PV plants. A specific analysis regarding several South Australia and United States basins is given. The algae bloom problem is discussed: human activities have a strong impact on water quality as they produce pollutants or induce the process of water eutrophication due to the excess of organic compounds (waste or fertilizers) and the consequent biological process. The positive impact of floating or submerged plants is studied with respect to this problem and we show that these plants can be used not only for energy production but also to reduce this plague.

The Floating PV Plant

The floating PV concept is outlined and the first pioneering works are briefly described. A model of a raft is proposed as the basic component of a floating platform. Its advantages are described in detail. The cost and the optimization problem are discussed. The system of cooling the PV modules is analyzed. The mooring system is analyzed for fixed systems and for plants with tracking. The possibility to consider strong variations of the water level, typical of hydroelectric basins, is also considered. The tracking mechanism is discussed and several solutions are compared with particular attention to the tracking system without confinement, which seems to be the most promising one. Wind load and waves impact on floating structures are discussed in their basic aspects. References to the vast literature on this subject and wind load simulations are given. The possibility of extending the floating concept to off-shore plants is discussed.

Introduction to PV Plants

Basics concepts of photovoltaic (PV) devices are discussed starting from the photovoltaic effects and semiconductor behavior. The structure of silicon cells is briefly analyzed as well as the solutions for assembling cells in a PV panel.

Concentration Systems and Floating Plants

A review of low concentration systems is given with emphasis on the system with flat reflectors. The use of reflectors increases the energy yield but generally requires tracking and cooling systems. The advantages of installing these on a floating platform are considerable, since cooling and tracking systems can be easily implemented at a low cost. The reduction of gray energy is discussed and several solutions for concentration are analyzed in detail: • the possibility of using reflectors positioned at the rear of the modules,

Submerged PV Systems

Light absorption by water is analyzed. The physics of photovoltaic (PV) modules submerged in water is explored in detail. Light reflection and impendence entry is discussed as well as the thermal drift effect. Efficiency of submerged panel is given versus the water layer thickness. Test of submerged PV panels are analyzed, implementations and projects of submerged plants are shown.