Transparent Solar: The Technology of the Future?

What if your phone, your car, your home and office could be charged by the sun? Transparent solar technologies have the potential to transform cities from massive energy consumers to energy producers.

What is “transparent solar” anyway?

Transparent solar is cutting-edge technology that absorbs and utilizes light energy through windows or any glass surface—no matter the angle.

Although researchers have developed different approaches to transparent solar technologies, most act as more of a transparent solar concentrator. This means that they’re designed to absorb specific UV and infrared light wavelengths that are not visible to the human eye.

They can be

• Inorganic
• Organic
• Fully transparent
• Tinted or semi-transparent
• Non-wavelength-selective (using small opaque PV cells spaced out over transparent substrate)

Why transparent solar?

Sure, we have plenty of solar panels already on the market. But think about where these are being placed—rooftops and fields. To power the world with solar, we would need a MASSIVE amount of surface area for all the panels, almost 200,000 square miles! Where are we getting all this space?

Integrating transparent solar into any sheet of glass makes use of already existing architectural space. This makes it a “Building Integrated Photovoltaic” (BIPV).

There are already an estimated 5-7 billion square meters of glass surface in the US alone. Think of all the skyscrapers in existence or under construction whose windows could harness solar energy. Buildings alone have the potential to meet about 40% of the country’s annual energy demand.

ADDED BONUS: BIPV contributes to energy efficiency by blocking infrared solar heat from entering buildings.

Ultimately, BIPV could lead to net-zero energy buildings, which could greatly help cities meet greenhouse gas emissions targets and other climate goals.

But can it actually work?

I know this sounds like a 1960s’ fantasy of the future, but it’s already happening on the ground! In addition to better and more research on creating efficient and feasible transparent solar technologies, actual projects are popping up around the globe.

Let’s look at some real life examples . . .

King’s Cross Station in London

This project consists of 1,392 panels that are non-wavelength-specific (mentioned above). It supplies 175,000 kWh of solar power per year, which is around 10% of the building’s total demand.

A great part about this project is that it was completed entirely without closing down the station, demonstrating how easy it is to retrofit buildings and structures to include transparent solar.

Copenhagen International School

This incredible design uses 12,000 sea-foam hued (but otherwise clear) solar panels all over the building’s windows and façade. Not only does this look spectacular, it also produces 200 MWh of energy annually. This is over half of the energy the building consumes.

We have proof that this technology can be implemented. But can it be scaled up?

Here are some important considerations:

• Cost—this is difficult to estimate because this technology is still so new. But with mass production and deployment PLUS the fact that we can use existing glass and window frames, the manufacturing cost may be 50% lower than that of conventional PV.
• Efficiency—there is an efficiency/transparency tradeoff. Typically the higher the transparency, the lower the efficiency. Currently, the highest transparent solar efficiency is around 10%. This is quite far from conventional PV efficiency.
• Operating lifetime—this is especially important with organic solar cells. They degrade when exposed to oxygen or water vapor and are affected by extreme high and low temperatures. For this to be feasible, we need cells that have a decent lifetime.
• Lifecycle impacts—these have not been widely studied yet. However, environmental justice concerns may exist at every stage of the supply chain and throughout the lifecycle of a transparent solar cell. We need to make sure not to reproduce the problems with traditional solar (mining for rare earth minerals, waste, contamination, water use, social issues).
• Equitable distribution—currently, racial and ethnic minorities have less access to solar power regardless of income. As we scale this technology up, we must focus on improving solar energy access to marginalized communities.

So, is transparent solar the technology of the future?

I don’t have a transparent solar-covered crystal ball! But I do know that there are ways we all can push for renewable energies to be increased. Doing so could help drive the scaling up of transparent solar.

Here are a few ways you can get involved:

• At the municipal level:
  • Attend meetings held by energy committees, your energy provider, or other town departments, and express your desire for more renewable energy.
  • Check if your municipality has Community Choice Aggregation or Municipal Solar—if so, support initiatives for increased solar.
• At the state level:
  • Vote for government officials who advocate for renewable energy and/or climate action.
  • Call your representatives during legislative sessions to express your support for renewables.
• At the federal level:
  • Vote for government officials who advocate for renewable energy and/or climate action.
• At the global level:
  • We all have the ability to reach an unprecedented number of people with social media. Make yourself heard! Have conversations about climate change solutions, including renewable energy if that interests and inspires you. You can inspire change on- and off-line with this wonderful human connection.

Technology is defined as “the skills, methods, and processes used to achieve goals.” Let’s work together toward a shared goal—a future where there is equitable and affordable access to clean, renewable energy. If transparent solar is a technology that will help get us there, great!

But it will take a lot more than one renewable technology to realize a truly sustainable and regenerative future. So let’s keep putting our heads together to generate more skills, methods, processes, connections and ideas.