A Greener View: Are Solar Cell Windows the Next Big Thing?

by | May 31, 2021 | Blog

Green solar window concept with the forest in the city.

Summary

  • Solar cell windows are transparent panels that resemble glass window panes. The first-ever fully transparent solar concentrator was created in 2014 by scientists at Michigan State University (MSU). Then, in 2020, researchers in the US and Europe achieved full transparency for the solar glass, which is something the industry was struggling to achieve.
  • A see-through solar panel is essentially a counterintuitive idea, as solar cells are required to absorb sunlight (photons) and convert them into energy (electrons). When a solar glass is made to be transparent, the sunlight passes through the middle, defeating the purpose of utilising sunlight.
  • There are many advantages and disadvantages to the current solar cell window technology. Some of the positives include effectiveness in low lighting, poor angles, and robust panel design. However, the negatives, consist of seasonal energy generation, internal requirements, and cost.
  • Solar cell windows have the potential to become a non-intrusive technology that could be scaled across a range of commercial and industrial applications, from handheld devices to skyscrapers. This is, however, a vision for the future, as the concept of the see-through solar windows is not yet ready for mass commercial production.

Introduction

We see glass everywhere, from high rise buildings to large skylights being installed in our home renovations. Now, wouldn’t it be great if these glass window panes did not function to only allow light into our rooms, but also to generate the energy needed to power everything inside? Solar tech companies are taking steps to transform the global solar energy landscape to make this a reality.

There are now some promising technologies out there, already in the advanced stages of development, that could arrive on the market soon. With this solar innovation, we will be able to not only be able to make use of solar arrays and roof panels for Sunpower but also on our everyday window. Just think how much power a highrise building could potentially generate from top to bottom solar cell windows.

This article will look into what precisely solar cell windows are, the pros and cons that currently come along with them, and whether this new solar technology may replace the need for large solar arrays. Who knows, you may be looking out at a greener view soon!

What is a solar cell window?

They are see-through solar panels that resemble glass window panes.

Solar cell windows are pretty much what you would expect them to be. They are see-through solar panels that resemble glass window panes. However, there is a bit more to them than a regular window, as the panes include the solar PV technology necessary to generate electricity from the sun. In theory, this new solar technology means there is the potential to one day replace our standard glass windows with solar cell windows, increasing the renewable energy generated from our homes and businesses.

Solar cell window technology is frequently referred to as building-integrated photovoltaics (BIPV), but this phrase can also be applied to roof-integrated panels or solar roof tiles. These window-based technologies are seen by many as more visually attractive and easier to maintain than adding solar panels to a roof. Standard solar roof panels are seen as unattractive by many house-proud homeowners.

Photovoltaic glass is considered one of the most cutting-edge new solar panel technologies out there, as it looks to be a game-changer in developing the scope of solar power. In 2014, some researchers at Michigan State University (MSU) created the first-ever fully transparent solar concentrator. This clear solar panel has given us the potential to turn virtually any glass sheet or window into a PV cell. By 2020, researchers in the US and Europe managed to achieve full transparency of solar glass, which is something the industry was struggling to accomplish. We don’t want to be sitting around in dark rooms, even if it is for the benefit of generating green energy.

These unique transparent solar panels have the potential to be positioned in a range of settings. For example, they could be deployed on skyscrapers with huge windows to a simple portable device such as laptops, tablets, or even mobile phones. These solar power windows in the future could replace the standard glass windows in our offices and homes. Solar technology holds the potential to virtually turn every building in the world into a solar power producer- eliminating arguments about where solar panels should be placed, and if they should be ‘out of sight’.

A transparent solar panel is actually a counterintuitive idea as solar cells must absorb sunlight (photons) and convert them into energy (electrons). When a solar glass is made to be transparent, the sunlight theoretically passes through the middle, which defeats the purpose of utilising sunlight. Amazingly, this new solar panel technology is transforming the manner in which solar cells absorb light.

The solar cells selectively harness a part of the solar spectrum that is invisible to the naked human eye, while letting the normal (visible) light pass through. To accomplish this technological phenomenon, solar scientists have developed the transparent luminescent solar concentrator (TLSC) rather than trying to do the impossible. They have succeeded in creating a transparent photovoltaic glass cell.

The transparent luminescent solar concentrator (TLSC)  is composed of organic salts that are devised to absorb specific invisible UV and infrared light wavelengths. They then shine (luminesce) as another invisible wavelength. This new wavelength is then driven to the edge of the window plastic, where thin PV solar cell strips then transform it into energy.

These are transparent solar panels that could literally generate electricity from anywhere one would have normal glass- windows being the most practical choice. Blinds are also being looked at as another potential part of a building’s window that can generate electricity, but we will save that for another day. For now, let’s move on to the advantages and disadvantages of solar panel windows.Tooltip Text

The Advantages and Disadvantages of Solar Cell Windows

Day and night window view to represent seasonal solar energy production.

As great as solar cell windows may be, compared to other types of renewable energy, they are still somewhat seasonal as there are periods of no sunlight.

Like many renewable energy advocates, if you are keen to get solar investing in new solar systems, it is worth being aware of the pros and cons associated with solar energy. Although there are many advantages of new technologies, such as solar cell windows, there are some disadvantages, especially in the early developmental stages.

Here are a few of the incredible advantages of solar cell windows:

  • Performance at poor angles – Thin-film solar cells are capable of running at a high-efficiency level, even when they are not positioned at an optimal angle for direct sunlight absorption. This results in a more significant potential payoff after installation, including placing them vertically on buildings without compromising the overall efficiency. This is a big plus, especially in urban settings where ample horizontal space is limited.
  • Effectiveness in low lighting – Thin-film solar cells are able to operate in as little as 10% sunlight. This means that the number of hours during which electricity can be produced is greatly extended in comparison to traditional solar panels. It results in a more consistent energy yield overall, which is great for locations that often experience darker days and unfavourable weather. In addition to this, thin-film alignment will cause panels to be less affected by shading, which is something many highly populated areas struggle with.
  • Superior heat tolerance – These solar cell panels are less affected by high temperatures. Why is this important? Well, as a result, they do not require any ventilation in order to perform at optimal levels. The thin film also tends to perform at a higher amount of efficiency over a more extensive temperature range. This means that solar cell windows can receive the maximum potential for energy production.
  • Comparable costs –  Once developed and produced at an economic level, the initial cost of installation should be comparable to that of conventional building materials. However, it is important to note that solar cell windows will have additional multi-functionality (Acting as power providers and windows at once), which makes them an economically superior option.
  • Robust panels – Solar cell panels are surprisingly rigid and incredibly tough as they have laminated glass that works to improve the overall functionality of the panels. As these solar cell windows are very strong, it increases their potential for installation applications.

With the advantages, there also comes some disadvantages of solar cell windows (which luckily come with some solutions). Here are a few to consider before looking to upgrade your windows:
 

  • Internal requirements – Not all households will be able to satisfy their energy requirements and get the most out of their solar cell windows yet. Solar cells are incredibly sensitive in terms of their position, which means that if there is constant shade on your property, it is difficult to exploit solar energy for the complete running of the building and its occupants. The solution would be to stay connected to the grid and continue to buy power from others when needed.
  • High solar investment – The current installation cost of solar cell window panels is pretty high. However, you could justify the cost when considering that (once installed), the panels are producing free renewable energy. One possible solution to this drawback is that some banks and governments offer energy lending or green incentives, which motivates investing in green energy.
  • Seasonal energy – As great as solar cell windows may be, compared to other types of renewable energy, they are still somewhat seasonal, as there are periods of no sunlight. A potential solution is to connect the solar installation to the grid and purchase power from the public electricity network when needed, such as during intervals where there is a smaller amount of energy to accumulate. Investing in solar battery storage systems may also be an excellent direction to take, as it can store the energy produced during peak hours and make it instantly available for rainy and overcast days.
  • Solar cell windows on older buildings – It might be harder to install solar cell panels on older homes. This is due to the fact that older architectural designs often shaded the windows. At the same time, flat roofs where drifting snow may fall below the racks becomes too heavy for a roof with solar panels, so that the windows could be a good alternative. Therefore, the building design must be assessed before inquiring about solar cell windows being installed.

Will Solar Cell Windows Replace All Conventional Glass Windows?

Solar cell windows are a vision for the future as the concept of the see-through solar windows is not yet ready for mass commercial production.

You will not see solar windows being installed everywhere as standard, because most photovoltaic glass is not transparent. This is due to the problem that, when solar glass is being made to appear transparent, it is not able to absorb sufficient energy to produce electricity at a significant level to justify the cost.

Currently, solar cell windows are not an adequate replacement for window glass. However, once mass production begins for transparent solar panels, researchers estimate that transparent luminescent solar concentrators (TLSC) should be capable of delivering an effectiveness of about 10%. This may seem like an insignificant figure; however, on a global scale, when almost every window in our homes and office buildings consists of transparent solar panels, the results could be transformative when it comes to energy production.

With mass production, of course, the transparent solar panel and deployment costs will come down. It has the potential to become a non-intrusive technology that can be scaled across the range of commercial and industrial applications to handheld consumer devices while remaining economical. This is a vision for the future, as the concept of see-through solar windows is not yet ready for mass commercial production. For the solar industry to create see-through solar panels which produce sufficient electricity from the sun, it will likely require quantum dot technology or nanotechnology. This would permit light through the window while still generating electricity, as the energy would be absorbed through the quantum dots.

Photovoltaic glass is, however, in production and being used in building construction all over the world. It is being included in substantial commercial buildings, bus stops, and petrol stations to be used as the walls and roofs of conservatories, greenhouses, skylights, and facades. Investors and consumers alike are becoming increasingly interested in solar window technology. Apart from the environmental aspect, people are also lured in by their discreet appearance, ability to lower utility bills, and ease of integrating with existing structures.

Homeowners, in particular, are attracted to the fact that solar panels on a glazed window are thin and hard to detect on the surface of the window’s glass. This means they do not create an eyesore that so many associated with conventional home solar panel installations. On top of all this, it is crucial to remember that the solar panels are hard at work converting sunlight into energy, so looks aren’t everything.

Solar lights and solar blinds are also being developed. At the National Renewable Energy Laboratory (NREL), scientists have managed to create a more powerful energy-collecting system for windows. This system could make commercial buildings and homes more energy-efficient without damaging their aesthetic appeal. It is achieved with the same solar collecting technology, which occurs in the form of a thin panel that is placed in an existing window. The panels start to work as soon as they are exposed to light.

Although the technology used in them is microscopic, these solar windows significantly minimise traditional energy usage. This is mainly due to the fact that they change colour as needed to maximise energy absorption across the solar spectrum throughout the day. While the power output of solar windows is remarkable, research is ongoing to prolong their lifespan. Along with the National Renewable Energy Laboratory (NREL), private companies and educational facilities are also working on ways to make solar windows even more efficient and affordable.

Closing Thoughts

With so many opportunities and solutions available, the solar energy industry is continuously exploring new methods to generate solar energy. A substantial quantity of time is also spent upon improving existing technology, so it is no surprise that many solar companies are actively taking steps to create their own more attractive and energy-efficient versions of the first solar windows.

If solar technology continues to develop at the rate we have seen over the past decade, soon our homes, office buildings, and shop windows may be able to generate solar power from places other than the roof. The solar market is forever evolving and expanding. They are on the search for new solar technologies aimed at spreading solar energy generation beyond traditional rooftop and ground-mount solar panels. Solar cell windows are on the top of the list, and could represent part of the solar market’s future very soon.

FAQs

 

How much energy do solar windows produce?

The solar power effectiveness of the fully transparent solar panels is currently about 1%, with an estimated potential of 5%. Conventional solar panels average efficiency of 15%, so comparable efficiencies of 5% and 7.2% for the fully and partially transparent panels, respectively, are still relatively low. These numbers alone might not mean much to many people, but you can get a better idea of what they actually equate to when you put them into a practical perspective. Each solar window can potentially generate anywhere between 8 to 10 watts daily. The amount generated will depend on the volume of solar lights absorbed through its cells. The power produced is a sufficient amount to charge one mobile phone per meter of solar window twice a day fully. This means that everyone in the office could power their phone- simply by replacing an already-existing window. Any excess energy that the windows produce and is not needed to be used that day is sent to a battery, where it remains stored until it is required.

 

How much do solar cell windows cost?

The majority of solar cell windows are not yet available on the market, so there is little information on the exact costs. What we do know is that, as the technology is still new, the solar cell windows are not mass-produced, so they are not yet economically viable for the majority of residential installations. If you are looking to invest in solar power, it makes sense to stick to conventional solar panels for now, or to invest in solar power shares. There are several ways you can become involved in helping the advancement of solar power technology. Rather than rushing out to buy solar cell windows, which might not be the best solar product on the market at the moment, you could consider investing in solar power stocks to support the industry.

 

Why isn’t solar glass technology everywhere?

The reason solar glass technology is not everywhere is simply due to functionality. Conventional solar panels use photovoltaic technology, which means the panels capture energy in the way of light and use it to produce electricity. As windows are intended to let light pass through, windows that double up to act as solar panels need to reconcile, allowing incoming light through to brighten a room and also capturing incoming light to use for energy creation. A solar window that does not let adequate light in will merely act as a vertically mounted solar panel. If the solar window allows too much light in, the window can’t generate enough electricity to be cost-effective. Solar panel windows need to become truly building-integrated and unobtrusive by utilising transparent solar panel technology before we see them being installed as the new norm.

 

Are there solar cell windows in Canada?

Yes, there is a solar cell window in Canada. In 2019, Belnor Engineering installed Canada’s first-ever transparent photovoltaic solar window. It was established in Toronto at the Centre for Innovation, Technology & Entrepreneurship (CITE Facility) Seneca College’s Newnham Campus. The sizeable solar window of 20% transparency comprises 18 photovoltaic glass panels (totalling an area of 510 square feet). The total power generated at its peak from this kind of installation is close to 1.3 Kilowatts.

 

How transparent is a solar cell window?

The term ‘transparent solar panel’ can be a little deceptive. There are solar panels that are slightly see-through, and those that are completely see-through. Both are technically classed as transparent solar panels. Transparency is a spectrum, usually stated as a percentage. If a solar company produces panels with 30% transparency, you may not be able to see out of them with complete clarity, but they are still classed as transparent solar cell windows. The solar industry is working towards creating 100% transparency solar panels, but they are not yet available.