BIPV/T facades – A new opportunity for integrated collector-storage solar water heaters? Part 1: State-of-the-art, theory and potential

Abstract

Building Integrated Photovoltaic Thermal (BIPV/T) systems are promising solutions for serving local electricity and heat demands in Net Zero Energy Buildings (NZEB). Despite BIPV/T offering clear energetic and space saving advantages compared to separate BIPV and solar thermal, overheating occurs when no thermal demand exists, resulting in reduced yields, stagnation damage, and excessive fluid pressures. Whilst continuous fluid flows mitigate overheating, corresponding parasitic demands and space requirements are significant (pumps, large storage tanks or heat rejection equipment). This two-part study examines an alternative approach to BIPV/T, addressing overheating by combining BIPV and Integrated Collector-Storage Solar Water Heater (ICSSWH) concepts. Solar heating capabilities of ICSSWH collectors are well established and their overnight heat loss characteristics provide passive overheating control. BIPV-ICSSWH approaches have yet to be investigated extensively. This paper (Part 1 of 2) reviews state-of-the-art and performance benchmarks in BIPV/T and ICSSWH; proposes new performance metrics enabling fairer comparisons; and develops a heat transfer model for BIPV-ICSSWH façade elements employing Planar Liquid-Vapour Thermal Diodes (PLVTD) to regulate absorber temperatures and heat losses. Multi-day solar thermal collection, photovoltaic generation, and overnight heat retention behaviours are simulated in different climates. The modelling results (experimentally validated in Part 2 of 2)suggests BIPV-PLVTD-ICSSWHs with single transparent covers and ≈90% PLVTD diodicity achieve , ≈60% solar thermal efficiency at N≈0.035m 2 K•W -1 , PV/T performance ratio PRT3≈75%, and heat loss coefficient Ur,sysAsys/u≈20 W•m -3 K -1 . The novel BIPV-PLVTD-ICSSWH approach can reduce maximum stagnation by 20°C compared to conventional BIPV/T and therefore support NZEB realisation during global efforts to tackle the climate crisis.

Review analysis of COVID-19 impact on electricity demand for residential buildings

“…In addition, renewable energy technologies can be deployed to improve the energy efficiency and sustainability of new as well as existing residential buildings [ [35] , [36] , [37] ]. Among the renewable energy based solutions that are suitable for residential buildings include the following measures: Install building integrated Photovoltaic (BIPV) systems to generate electricity using roofs, walls, windows, as well as shading devices [ [38] , [39] , [40] , [41] , [42] ].…”

State of the Art of Technologies in Adaptive Dynamic Building Envelopes (ADBEs)

“…Water is frequently utilized as a working medium in ADBE design, thanks to its high specific heat capacity, low cost, abundance, and non-toxicity [59,[66][67][68][69][70]. There are several options regarding its utilization in the literature [71,72].…”

“…A variety of different technologies are combined in the category "other" in Figure 8a. Those account for technologies such as biocomposite materials in façades [170] or the implementation of an innovative-coupled glass with an internal IR treatment [66].…”

A solar backup system to provide reliable energy in presence of unplanned power outages

“…The temperature of hot water in the SHW's tank is calculated by the following equation (Pugsley et al, 2020):…”