Particular Architectures

Floating PV

PVsyst has not carried out dedicated studies on floating PV (FPV) installations. We advise users either to perform their own measurements or to use values from the literature, if applicable to their mounting structure and climate. From a physics perspective, note that:

• PV modules are not typically in direct contact with water. The heat loss mechanisms are similar to those of inland scenarios. The main cooling gains come from lower air temperatures above water and higher wind speeds.
• The measured thermal loss coefficient \(U\) varies greatly depending on the mounting structure. As for land-based PV, open structures have greater heat loss.

Some studies¹, ² have measured PVsyst \(U\) coefficients for several FPV installations.

Finally, it is also possible to import PV array temperature (TArrMes) into PVsyst using the custom weather import. This allows you to run the PVsyst simulation directly with the provided temperature, rather than computing it from the \(U\) coefficients, ambient temperature \(T_{\mathsf{amb}}\) (Tamb), and global irradiance (GlobInc).

Thermal behaviour of an array on a tilted roof

When a PV array is installed on a tilted roof, with an air duct between the roof and the modules, the air circulation is driven by the temperature difference between the incoming air (ambient air) and the outgoing air.

Because the thermal capacity of air is low, the air is heated as it passes under the first modules, so there may no longer be significant heat exchange for the upper modules, which then behave as if they were in a "fully insulated" situation. In this case, the array temperature is very difficult to evaluate and may be strongly inhomogeneous. Developing an accurate model would require a detailed description of the air duct thickness, its length, etc. This is outside the scope of PVsyst.

At present, PVsyst does not treat this inhomogeneity and instead considers an average temperature.