BIPV-Powered Smart Windows Utilizing Photovoltaic and Electrochromic Devices

A BIPV-powered smart window comprising a building-integrated photovoltaic (BIPV) panel and an all-solid-state electrochromic (EC) stack is proposed. In the proposed device, the output voltage of the BIPV panel varies in accordance with the intensity of the incident light and is modulated in such a way as to generate the EC stack voltage required to maintain the indoor illuminance within a specified range. Two different EC stacks are fabricated and characterized, namely one stack comprising ITO/WO3/Ta2O5/ITO and one stack comprising ITO/WO3/lithium-polymer electrolyte/ITO. It is shown that of the two stacks, the ITO/WO3/lithium-polymer electrolyte/ITO stack has a larger absorptance (i.e., approximately 99% at a driving voltage of 3.5 V). The experimental results show that the smart window incorporating an ITO/WO3/lithium-polymer electrolyte/ITO stack with an electrolyte thickness of 1.0 μm provides an indoor illuminance range of 750–1,500 Lux under typical summertime conditions in Taiwan

Recent developments in solar energy-harvesting technologies for building integration and distributed energy generation

We present a review of the current state of the field for a rapidly evolving group of technologies related to solar energy harvesting in built environments. In particular, we focus on recent achievements in enabling the widespread distributed generation of electric energy assisted by energy capture in semi-transparent or even optically clear glazing systems and building wall areas. Whilst concentrating on recent cutting-edge results achieved in the integration of traditional photovoltaic device types into novel concentrator-type windows and glazings, we compare the main performance characteristics reported with these using more conventional (opaque or semi-transparent) solar cell technologies. A critical overview of the current status and future application potential of multiple existing and emergent energy harvesting technologies for building integration is provided

Advances in switchable and highly insulating autonomous (self-powered) glazing systems for adaptive low energy buildings

Building energy reduction requires highly advanced low heat loss, heat gain and comfortable daylight allowing glazing. Presently available glazing systems are classified mainly in two categories, controlling solar heat gain and controlling low heat loss. Low heat loss through glazing systems can be achieved by (i) suppression of convection in the air between the outer panes by use of multiple glass panes or aerogels, (ii) having an inert gas or vacuum between the panes to reduce or eliminate respectively convective heat transfer. In all these systems, low emissivity coatings are also required to reduce the radiative heat transfer. Low heat glazing allows large areas of a building façade to be glazed without large attendant heat losses. However, they require the addition of an ability to switch from transparent to opaque to avoid excessive solar heat gain and to control glare. Electrically actuated electrochromic, liquid crystal and suspended particle device glazing systems and non-electrically-actuated thermochromic, thermotropic, and gasochromic glazing systems offer control of solar heat gain control and daylight. Recent relevant developments are reviewed with the contemporary status of each technology provided

A review of advanced architectural glazing technologies for solar energy conversion and intelligent daylighting control

Efficient management of solar radiation through architectural glazing is a key strategy for achieving a comfortable indoor environment with minimum energy consumption. Conventional glazing consisting of a single or multiple glass pane(s) exhibits high visible light transmittance and solar heat gain coefficient, which can be a double-edged sword, i.e., it allows sufficient sunlight to enter the building interior space for passive heating and lighting; on the other hand, it can cause glare discomfort and large cooling energy consumption. Among the various advanced glazing technologies being developed, Building Integrated Photovoltaic (BIPV) glazing has a prominent position due to its ability to reduce cooling load and visual discomfort while simultaneously generating electricity from sunlight. Recent years have witnessed remarkable advances in low-concentration optics such as Dielectric based Compound Parabolic Concentrators (DiCPCs), with a growing interest in the development of Building Integrated Concentrating Photovoltaic (BICPV) glazing to improve light harvesting and electric power output. One of the challenges faced by traditional BIPV glazing systems is the lack of dynamic control over daylight and solar heat transmission to cope with variations in weather conditions and seasonal heating/cooling demands of buildings. A promising solution is to integrate an optically switchable smart material into a BIPV glazing system, which enables dynamic daylighting control in addition to solar power conversion. Thermotropic (TT) hydrogel materials such as poly(N-isopropylacrylamide) (PNIPAm) and Hydroxypropyl Cellulose (HPC) are potential candidates for hybrid BIPV smart glazing applications, due to their unique features such as high visible transparency (in the clear state), strong light-scattering capability (in the translucent state) and large solar energy modulation. This paper reviews various types of electricity-generating glazing technologies including BIPV glazing and BICPV glazing, as well as smart glazing technologies with a particular focus on TT hydrogel integrated glazing. The characteristics, benefits and limitations of hybrid BIPV smart glazing are also evaluated. Finally, the challenges and research opportunities in this emerging field are discussed

Inorganic and Organic Photovoltaic Materials for Powering Electrochromic Systems

abstract: ABSTRACT Autonomous smart windows may be integrated with a stack of active components, such as electrochromic devices, to modulate the opacity/transparency by an applied voltage. Here, we describe the processing and performance of two classes of visibly-transparent photovoltaic materials, namely inorganic (ZnO thin film) and fully organic (PCDTBT:PC70BM), for integration with electrochromic stacks. Sputtered ZnO (2% Mn) films on ITO, with transparency in the visible range, were used to fabricate metal-semiconductor (MS), metal-insulator-semiconductor (MIS), and p-i-n heterojunction devices, and their photovoltaic conversion under ultraviolet (UV) illumination was evaluated with and without oxygen plasma-treated surface electrodes (Au, Ag, Al, and Ti/Ag). The MS Schottky parameters were fitted against the generalized Bardeen model to obtain the density of interface states (Dit ≈ 8.0×1011 eV−1cm−2) and neutral level (Eo ≈ -5.2 eV). These devices exhibited photoconductive behavior at λ = 365 nm, and low-noise Ag-ZnO detectors exhibited responsivity (R) and photoconductive gain (G) of 1.93×10−4 A/W and 6.57×10−4, respectively. Confirmed via matched-pair analysis, post-metallization, oxygen plasma treatment of Ag and Ti/Ag electrodes resulted in increased Schottky barrier heights, which maximized with a 2 nm SiO2 electron blocking layer (EBL), coupled with the suppression of recombination at the metal/semiconductor interface and blocking of majority carriers. For interdigitated devices under monochromatic UV-C illumination, the open-circuit voltage (Voc) was 1.2 V and short circuit current density (Jsc), due to minority carrier tunneling, was 0.68 mA/cm2. A fully organic bulk heterojunction photovoltaic device, composed of poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyli2’,1’,3’-benzothiadiazole)]:phenyl-C71-butyric-acidmethyl (PCDTBT:PC70BM), with corresponding electron and hole transport layers, i.e., LiF with Al contact and conducting/non-conducting (nc) PEDOT:PSS (with ITO/PET or Ag nanowire/PDMS contacts; the illuminating side), respectively, was developed. The PCDTBT/PC70BM/PEDOT:PSS(nc)/ITO/PET stack exhibited the highest performance: power conversion efficiency (PCE) ≈ 3%, Voc = 0.9V, and Jsc ≈ 10-15 mA/cm2. These stacks exhibited high visible range transparency, and provided the requisite power for a switchable electrochromic stack having an inkjet-printed, optically-active layer of tungsten trioxide (WO3), peroxo-tungstic acid dihydrate, and titania (TiO2) nano-particle-based blend. The electrochromic stacks (i.e., PET/ITO/LiClO4/WO3 on ITO/PET and Ag nanowire/PDMS substrates) exhibited optical switching under external bias from the PV stack (or an electrical outlet), with 7 s coloration time, 8 s bleaching time, and 0.36-0.75 optical modulation at λ = 525 nm. The devices were paired using an Internet of Things controller that enabled wireless switching.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Transparent photovoltaic technologies: Current trends towards upscaling

The world energy scenario is now living significant contributions coming from the photovoltaic field: new organic/inorganic hybrid materials have emerged in recent years, and in some cases these emerging strategies have exceeded the performance of traditional crystalline silicon. The next step concerns the integration of these technologies in smart buildings, in order to maximize the active surface capable of producing electricity and to contain the costs of air conditioning without affecting the amount of light needed. This review focuses on some of the most recent strategies developed to this purpose. Following an initial background on solar cells and figures of merit to characterize a transparent photovoltaic panel, the manuscript deals with a thorough analysis of wavelength-selective and non-wavelength selective devices, mentioning the main outcomes in the recent years. This distinction is proposed for both solar cells and solar concentrators, two areas in rapid evolution in academia and company worlds. A newly proposed case study and the example of a pre-industrial reality that has just started to scale-up this technology conclude this review, leaving to the reader a rich background on this highly-in-vogue field

Potential of building integrated and attached/applied photovoltaic (BIPV/BAPV) for adaptive less energy-hungry building's skin: A comprehensive review

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThe inclusion of photovoltaic (PV) technologies add extra functionalities in a building by replacing the conventional structural material and harnessing benign electricity aesthetically from PV. Building integration (BI) and building attached/applied (BA) are the two techniques to include PV in a building. Currently, first, and second-generation PV technologies are already included for BIPV and BAPV application in the form of wall, roof, and window whereas third generation PVs are under rigours exploration to find their potential suitability. To alleviate enhanced temperature from both BIPV and BAPV, active and passive cooling can be introduced, however passive techniques are influential in trimming down the temperature for retrofit building. Shading from snow, dust cover and nearby building can be an obstacle for BIPV/BAPV application. The hydrophobic (icephobic) self-cleaning coating is suited for snow covering PV while hydrophobic and hydrophilic are both applicable for anti-soiling. Electric vehicles, autonomous switchable glazing, low heat loss glazing and lightweight BIPV are the different future application for PV in BI and BA integration

Perovskite Solar Cells for BIPV Application: A Review

The rapid efficiency enhancement of perovskite solar cells (PSCs) make it a promising photovoltaic (PV) research, which has now drawn attention from industries and government organizations to invest for further development of PSC technology. PSC technology continuously develops into new and improved results. However, stability, toxicity, cost, material production and fabrication become the significant factors, which limits the expansion of PSCs. PSCs integration into a building in the form of building-integrated photovoltaic (BIPV) is one of the most holistic approaches to exploit it as a next-generation PV technology. Integration of high efficiency and semi-transparent PSC in BIPV is still not a well-established area. The purpose of this review is to get an overview of the relative scope of PSCs integration in the BIPV sector. This review demonstrates the benevolence of PSCs by stimulating energy conversion and its perspective and gradual evolution in terms of photovoltaic applications to address the challenge of increasing energy demand and their environmental impacts for BIPV adaptation. Understanding the critical impact regarding the materials and devices established portfolio for PSC integration BIPV are also discussed. In addition to highlighting the apparent advantages of using PSCs in terms of their demand, perspective and the limitations, challenges, new strategies of modification and relative scopes are also addressed in this review

Technological options and strategies towards zero energy buildings contributing to climate change mitigation: A systematic review

A systematic review of the technological options and strategies to achieve zero energy buildings was carried out to establish today state-of-the-art knowledge base and to present key design and performance factors that define those technologies with the final aim of contributing to climate change mitigation options of buildings. All relevant literature published from January 2013 to August 2019 was critically as- sessed. A total of 14,895 papers were identified and 220 reviews were evaluated as first literature source; this literature showed that the published information is diverse and not organized, therefore climates and building typologies is not possible solely through published information. Collected evidence shows that with appropriate design, buildings can contribute to climate change mitigation decreasing the embodied energy in the materials used in their construction and decreasing the energy demand and use during their operation phase.This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31 - MCIU/AEI/FEDER, UE). This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación (AEI) (RED2018-102431-T). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme