Thermal and electrical performance of an integrated PV-PCM system in double skin façades: A numerical study

In this article the performance of a system that integrates a photovoltaic (PV) layer and a phase change material (PCM) layer in a double skin façade (DSF) is investigated. A physical–mathematical model is developed to simulate the dynamic thermal behaviour of the system, and numerical simulations are carried out for different climates (Venice, Helsinki and Abu Dhabi) in order to evaluate the performance of the proposed solution.

The numerical model combines different validated codes for the simulation of optical, thermal, and electrical behaviour of PCM, PV and DSF. The model is then coupled with the indoor air heat balance equation to evaluate the impact of the proposed façade system on the heating and cooling energy demand.The adoption of a PCM layer in the DSF cavity, in combination with a semi-transparent PV layer, leads to a reduction in the monthly cooling energy demand in the 20–30% range.

This result is particularly relevant for hot climates – where cooling loads are seen throughout the year. The improvement in terms of heating load in more cold-dominated locations is limited. The smoothing of the PV module temperature leads to an increase in the electrical energy converted by the PV, with peak values of improvement in the range of 5–8% when the DSF is equipped with the PCM–PV configuration.

Ventilation strategies of the façade cavity, coupled with the correct selection of PCM (and of its transition-phase temperature range), are the key aspects to ensure effective management of the proposed technology.