The performance of a novel flat heat pipe based thermal and PV/T (photovoltaic and thermal systems) solar collector that can be used as an energy-active building envelope material

Abstract

a b s t r a c tA novel flat heat pipe design has been developed and utilised as a building envelope and thermal solar collector with and without (PV) bonded directly to its surface. The design of the new solar collector has been validated through full scale testing in Cardiff, UK where solar/thermal, uncooled PV and PV/T tests were carried out on three identical systems, simultaneously. The tests showed a solar/thermal energy conversion efficiency of around 64% for the collector with no PV and 50% for the system with the PV layer on it. The effect of cooling on the solar/electrical energy conversion efficiency was also investigated and an efficiency increase of about 15% was recorded for the cooled PV system due to the provided homogenous cooling. The new flat heat pipe solar collector is given the name "heat mat" and, in addition to being an efficient solar collector type, it is also designed to convert a building envelope materials to become energy-active. A full size roof that utilise this new building envelope material is reported in this paper to demonstrate the way this new collector is integrated as a building envelope material to form a roof. A thermal absorption test, in a controlled environment, from the ambient to the heat mat with no solar radiation is also reported. The test has proved the heat mat as an efficient thermal absorber from the ambient to the intermediate fluid that deliver the heat energy to the heat pump system.

Is enhanced radiative cooling of solar cell modules worth pursuing?

“…Changes to roof design on which the modules are mounted can add extra convective cooling from the module base [10,11] but add cost. Deliberate extraction of module heat as a source of useful heat or pre-heat, so called PV/T technology, also adds cooling [12] as do phase change materials (PCMs) which can be recharged at night [13].…”

Thermal management of solar cells using a nano-coated heat pipe plate: an indoor experimental study

“…Heat pipe technology has also been extensively investigated for PV cooling applications in several studies [36][37][38][39][40][41][42]. The significant advantage of heat pipe lies in its high heat transfer rate.…”

A review of thermal absorbers and their integration methods for the combined solar photovoltaic/thermal (PV/T) modules

“…This fluid boils and flows up to the condenser section of the heat pipe cooled itself using a manifold. The MHPA/heat mat bears the advantages of high heat transfer performance, high reliability, high compressive strength, low cost, and small contact thermal resistance because of its flat-plate structure [39,[71][72][73]. It can also be applied in cold regions when ammonium hydroxide is used as the working fluid.…”

“…Due to their flexibility, flexible PV/T modules can serve as rooftop shingles/tiles, irregular building facades, and the glazing for daylights. Integration of flexible PV/T modules into the profile of the roofing sheet is the most popular design that allows for heat and power to be generated from the integrated panels and transferred to a location within the building for purposes such as hot water supply [38], space heating [39], space cooling [40], and even fresh water production etc. [41].…”

“…Micro-channel heat pipe array (MHPA) [71][72][73], also termed as heat mat [39], is a flat-plate heat pipe based thermal absorber suitable for flat-plate and flexible PV/T modules. Fig.…”