- Dieter Moor
- Victor Rosenberg
- Mikhail Vasiliev
- ClearVue Technologies Ltd., Australia
Multiple modern glass and window products based on novel glazing designs, metal-dielectric coatings, and proprietary interlayer types have been developed recently. Advanced windows of today can control properties such as thermal emissivity, heat gain, colour, and transparency. In more recent and more novel glass products, solar energy harvesting through PV integration is also featured. Typically, semitransparent and also highly-transparent PV windows are purpose-designed, to include luminescent materials, special microstructures, and customized electric circuitry.
Recently, significant progress has been demonstrated in building integrated highly-transparent solar windows (VLT up to 70%, with Pmax ~ 30-33 Wp/m2, eg Clearvue PV Solar Windows); these are expected to add momentum towards the development of smart cities. These Clearvue window systems are, at present in 2021, the only type of high-transparency and clear construction materials capable of providing significant energy savings in buildings, simultaneously with renewable energy generation.
The technology has already been deployed and tested in both commercial property applications and in R&D greenhousing. Of special interest is the combination of properties provided by Clearvue solar window products, which includes significant power conversion efficiency (~3.3%), which is achieved in windows of colour rendering index of 99%, simultaneously featuring high PV Yield in multi-oriented building-integrated PV (BIPV) installations.
1. Introduction and Background
In recent years, there has been a significant progress demonstrated in both the R&D and industrialisation of novel BIPV products, materials, and also the window-integrated PV (WIPV) solar window systems. In particular, research progress has been made throughout the last decade in fields such as the development of large-area semi-transparent luminescent solar concentrators (LSC) and functional materials for use in solar windows (Li et al. 2016; Vasiliev et al. 2016; Alghamedi et al. 2014; Reinders et al. 2018; and others). Due to the globally recognised need to effectively decarbonise the built environments, novel types of BIPV and high-transparency solar windows are currently receiving increasing attention. Of special importance is the emergence of newly-commercialised glass-basedhigh-transparency and completely visually-clear BIPV technologies and systems, which have been demonstrated in practical architectural deployment applications.
Even with surging commodity prices increasing manufacturing costs for solar PV, its capacity additions were forecast to grow by 17% in 2021. This will set a new annual record of almost 160 GW in added generation capacity. Solar PV alone accounts for 60% of all renewable capacity additions (IEA Renewables-2021 (2021)). The addition of solar generation capacity in built environments is limited by the available unshaded roof and wall areas, therefore enabling windows to generate electricity simultaneously with providing HVAC and lighting energy savings represents an attractive way forward to achieve substantial and long-term decarbonisation. In buildings with high window-to-wall ratios, installing glazing systems with electricity generation provides perhaps the only viable way to decarbonise, even if window-generated electric power per unit area is (invariably) a fraction of that available from conventional PV.
2. Recent Developments in BIPV and Transparent Window-Integrated PV
Modern BIPV module suppliers have continued to offer an increasing range of products, trending towards systems of continually increasing power conversion efficiency (PCE), the choice of reflected colours, and with a brodening range of semi-transparency options. Multiple new technologies have appeared on the market in recent years, utilising new functional materials and system design types.
2.1. Current Trends and Technologies in Conventional BIPV
Multiple comprehensive reviews of recently-developed BIPV technologies and their performance characteristics are available, eg Biyik et al. (2017) and …….