How do solar windows work?

Solar windows are glass panels with photoelectric properties. This allows solar windows not only to let light into the buildings but also to absorb the sun’s energy and convert it into electricity.

While solar windows are still under development, they are a promising technology in the transition to cleaner energy. Combined with other types of Building Integrated Photovoltaics (BIPV) such as solar roofs and solar coatings, solar windows are integrated into the building structure rather than adding to it.

How do solar windows work

Whereas traditional solar panels are traditionally dark in color in order to absorb as much sunlight as possible, traditional windows must be transparent. Therefore, developers of solar windows need to let in light and generate enough electricity to make their manufacture and installation cost-effective.

A number of potential solar window solutions are still in the research and development stage, while only a few have reached the market recently.

ink and film

Optical ink or a thin optical film is placed over the glass, either during the manufacturing process or re-attached to existing windows. NEXT Energy Technologies produces transparent optical ink made from organic semiconductor materials that can be printed directly on windows.

Solar Window Technologies, by contrast, produces thin sheets of flexible glass coated with a photovoltaic liquid, designed to be installed on existing skyscraper windows.

Delicate panels and shades

Traditional small PV “micro panels” are positioned at the four sides or corners of windows so they do not block a large amount of light. Opaque or fully semi-transparent “solar blinds,” like those marketed by SolarGaps, take the micro-panel idea a step further, with miniature solar panels able to rotate to track the sun’s path while also serving as window shades.

Interlayers between parts

The double windows are manufactured with silicon solar cells between the two panes. EnergyGlass produces transparent interlayers of organic nanoparticles that are laminated between two layers of glass. The additional layer also provides more insulation than single or double-pane windows, so solar windows can reduce heating and cooling costs at the same time they produce electricity.

quantum dots

Quantum dots are nano-sized photovoltaic cells that are implanted inside the glass itself. Quantum dot technology uses transparent nanocrystals (basically, tiny glass beads) and quantum mechanics to convert solar energy into electricity.

Instead of absorbing visible light (thereby reducing the amount of light that passes through windows), quantum dots convert invisible ultraviolet light, which has more energy than visible light. The absorption of UV rays reduces their harmful effects on humans and furniture.

Quantum dots implanted in windows can also redirect infrared light toward photovoltaic cells, although infrared light has less energy than visible light, making it a less efficient converter of electricity.

solar window market

Solar glass technology is still developing. At the moment, developers are still trying to make solar windows economical – for both the manufacturer and the consumer.

Startups, including NEXT Energy Technologies and SolarGaps, have often relied on government research and development support to bring their products to market. Announced in April 2022, NEXT Energy Technologies’ first pilot project in Fremont, California, was awarded with a $3 million grant from the California Energy Commission, while SolarGaps has received funding from the European Union.

As with every new technology, not every product succeeds. Physee, a Dutch developer of sustainable building technology, installed PowerWindows as a pilot project at a Dutch bank in 2017. However, each window generates just enough electricity to charge several smartphones at the same time. While developing and marketing other innovative technologies, Physee still had to bring PowerWindows to the market.

The future of solar windows

Window glass manufacturing is a multi-billion dollar industry, and the construction of new buildings presents a tempting opportunity for solar glass developers. In the United States alone, construction begins on about 1.8 million new homes each year, according to the United States Census. Since January 2020, all newly built homes in California have been required to have solar PV as their source of electricity – a market that can be addressed for more than 100,000 new homes annually.

Perhaps more important is making retrofits efficient and economical. Buildings account for about 16% of greenhouse gas emissions, mostly from heating and cooling, according to the Intergovernmental Panel on Climate Change. A study by Architecture 2030 projects that two-thirds of all buildings in 2040 will be buildings in existence today – meaning retrofitting existing buildings will be vital in the fight to mitigate climate change. Whether in new construction or in retrofits, solar windows will need to play a vital role in the quest to electrify everything.

Frequently Asked Questions

  • Are solar windows eligible for government incentives?

  • Do sunshades use toxic materials?

    Most companies, such as Ubiquitous Energy, use only organic, non-toxic materials in their solar windows.

  • Are solar windows as effective as solar panels?

    Currently, solar windows are less efficient and less cost-effective than rooftop solar panels, but things are changing rapidly in the solar energy industry, with frequent improvements in technology, increased economies of scale, and dramatically lower prices. stay tuned

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