Floating Concentrated Photovoltaics: Part I

Background
Solaris Synergy has developed a low-cost concentrating photovoltaic (CPV) concept designed to float on water surfaces, utilizing inexpensive, easy-to-manufacture platforms, based on a unique, patent pending cooling technology. The two key objectives in developing this system are: a) significant reduction of the installed cost of the system; and b) the utilization of “industrial” water surfaces in order to reduce the use of land resources, while simultaneously preserving water quantity and quality.

The motivation for concentrating PV in general is to achieve cost reduction by reducing the total area of costly solar cells. However the concentration of solar energy has a major drawback in that it causes heating of the solar cells. This heating negatively impacts the efficiency and the lifetime of the solar cells. The proposed system is planned with an innovative evaporation/condensation cooling system utilizing the temperature of the water body upon which the system is floating – to cool down the PV cells to achieve higher efficiency and stability to diurnal thermal cycles and rapid thermal fluctuations. The proposed system comes together with a simple sun-tracking solution, achieved by slowly rotating the floating platform around its axis.

Market
CPV systems require direct sun radiation, and it is the areas of high direct insolation that are most suitable for this type of system. In these areas, Solaris Synergy is focusing particularly on “industrial” water bodies such as those associated with hydroelectric dams, pumped storage installations and cooling ponds of electric power plants – these energy production sites are especially attractive locations due to their existing power grid connections. High solar insolation causes undesirable water evaporation, and covering these surfaces with the Solaris Synergy system reduces evaporative water losses, providing an additional benefit to that of combining the two energy production systems on the same site.

An additional category of water surfaces, for which evaporation losses are critical, are those bodies of water – reservoirs, canals and aqueducts – belonging to water authorities supplying drinking and irrigation water. The Solaris Synergy system could provide both electricity (on or off grid) and surface coverage, reducing evaporation-induced losses. Additionally, water quality would be improved, since water coverage also reduces sun-stimulated algae growth.

A market study commissioned by Solaris Synergy has identified a total potential market of over 900 km2 of industrial water surfaces in the relevant high-insolation regions of the globe, capable of producing a total of greater than 90 GW of solar electricity. This does not include vast additional areas of natural non-industrial inland water surfaces such as lakes, ponds, etc. This “solar on water” market is in its infancy today, with only a very few players at an early stage of development, and there are currently little or no sales in this market.

System Description
The system is modular in structure, with each module (shown in Figure 2) capable of generating approximately 750 Wp of electricity. The modules’ main components are concentrating optics, photovoltaic cells, an evaporation/condensation cooling system and a floatation platform. The photovoltaic cells are assembled in a linear array along the focal axis of

FPV7_N_WP_Kassel_CPV.pdf