Hybrid solar cells (hybrid collectors, Photovoltaic Thermal, PVT) are also systems that use a combination of a solar panel and a collector [1]. Solar collectors convert solar energy into heat, while panels convert solar energy into electricity. Therefore, the collectors can heat domestic water and support the operation of central heating. The energy generated by the panels can also be used in various ways.
As described in the previous chapters, the efficiency of silicon-based photovoltaic cells decreases with increasing temperature. The rate of that increase is described by the temperature coefficient ¹. An example system is shown in Fig. 1 [2].

Figure 1: PVT panels dedicated for solar-assisted heat pump. Experimental installation at the Department of Energy of Politecnico of Milan. Aut. photo Rich Skiz, CC BY-SA 4.0, source: Wikimedia Commons.

The great advantage is to have one installation instead of two separate ones. This solution saves space in the case of limited installation space.

An implementation example is the ISIEtherm panel [3], which, according to the manufacturers, is expected to provide an increase in electrical gain (derived from solar energy) of at least \( 10\% \) annually in relation to systems without concentrators. It may be used for installations in swimming pools, hotel facilities and as heat pumps.