CPV: The CPV/T used is a solar collector that simultaneously generates the two most used forms of energy in the daily life: heat and electricity. This is possible, as it combines a photovoltaic panel and a solar thermal collector in the same module. It consists of a cylinder-parabolic reflector that concentrates the light of the sun ten times onto the receiver. The solar cells are optimized for concentrated solar radiation and each cell has 10 times more electric production than the same surface of standard solar cells, while they can be upgraded with more recent ones, as technology develops. The solar tracking system is controlled by a PLC control system to ensure that the collector follows the sun throughout the day and the focus is always on the solar cells.
ORC: An organic Rankine cycle (ORC) technology is used even more lately for the recovery of low-grade heat. The working fluid is a refrigerant, which can boil at temperature of even 60 oC, while the scale of such engines can be even of few kWs.
The ORC performance depends mainly on the evaporation/condensation temperature of the organic fluid (relevant to the heat source and heat sink characteristics respectively), while the selection of the proper organic fluid plays a key role in such applications, taking into consideration environmental criteria as well (e.g. ODP and GWP values).
Supercritical ORC shows some interesting features, such as a higher thermal efficiency under certain operating conditions and lower pinch-point temperature difference during the heat addition to the cycle, which means that a better exploitation of the available heat can be succeeded. These favourable characteristics lead to higher system efficiency, increasing the power output.
