Basics of the photovoltaic thermal module - Solar Energy Sciences and Engineering Applications - page 161

Figure 5.3.1 Cross section of a basic PV/T collector.
Figure 5.3.2 PV/T concept with liquid flowing on top of the PV module.
Figure 5.3.3 Channel PV/T concept with liquid flow beneath the PV cells.
photon-hole pairs and could in principle fully contribute to the generation of heat.
This generation can take place either in the cell or outside the cell if the cell material
does not absorb light at these wavelengths. The position of the heat generation in the
device determines the possible PV/T device geometries. In most concepts the entire heat
is generated in a simple device. In a two-absorber PV/T collector, however, part of the
heat is generated outside the PV cells (van Helden et al., 2004).
5.3.1 Different types of PV/T modules
The design concepts can be categorized into four types based on most other articles
about the PV/T systems. The most simple and basic design is a PV module attached
on the back of a metallic heat absorber plate as shown in Figure 5.3.1. In this module
concept, the distance between the heat generation device and heat collector determines
the performance of the PV/T modules. The second type of PV/T modules has water
that flows over the photovoltaic panel as shown in Figure 5.3.2. The third type of
modules, which is demonstrated in Figure 5.3.3, also uses a liquid, but to improve its
performance, the water flows through multiple channels underneath the PV panel to
remove generated heat. The fourth type of design makes the PV cells transparent and