Transparent solar panels: Are they useful?

There is no doubt that Spain is in a privileged position when it comes to solar power. Its geographical position and the Mediterranean climate mean that the country has about 300 days of sunshine a year, meaning that betting on solar energy as an alternative to fossil fuels is a very viable option. For example, in 2022, 31,987 GWh of solar energy, both thermal and photovoltaic, were generated in Spain. This accounted for 12% of the total annual energy produced, and a 24% increase year on year.

This increase in the use of solar panels can be attributed to several factors:

• Greater awareness of the importance of committing to renewable energies.
• Preference for self-consumption given the increase in energy prices and the instability of the electricity market.
• Subsidies and public aid to encourage its use by companies and individuals.
• Development of technology and more options to harness solar panels that are better adapted to the needs and possibilities of users.

What are transparent solar panels?

As we were saying, in recent years, technology has made huge steps forward in the development of devices that make it possible to generate energy easily, without requiring large installations. In this sense, the huge unsightly and difficult to install panels are now a thing of the past. Now there are numerous options including transparent solar panels: photovoltaic glass that can be used as windows.

This new option is totally transparent compared to the more traditional forms that were 70% to 100% opaque. This innovation allows for a much more versatile use of solar panels. Beyond installations on the roofs or solar farms, they can now be integrated much more comfortably into everyday life as they do not occupy extra space, and also open up infinite new possibilities when it comes to their use. In reality, it is a coating that can be placed on top of windows, or replace them completely.

Transparent solar panels are manufactured on demand, so the measurements, materials, shapes and colours can be customised to ensure they meet users' needs. As a result, they are becoming a real alternative when it comes to generating solar energy.

How do transparent solar panels work?

The operation of all solar panels is based on the same principle: absorb sunlight to convert it into electricity. However, while opaque solar panels capture all light waves (visible and invisible), in this case, solar cells are used to absorb only the infrared and ultraviolet wavelengths, which are not seen, letting through the light we see.

The technology behind these solar windows are transparent luminescent solar concentrators (TLSCs). These components, which are then combined with other materials such as glass or silicon, are made of organic salts designed to exclusively capture invisible light waves.

This is how solar windows are installed

Unlike traditional solar panels, transparent equivalents do not need to have a specific orientation or inclination. At a mechanical level, they are installed just like conventional windows, although each glass plate is then connected forming a network that is collected in the connection boxes.

What are the most common uses of transparent solar panels?

At present, transparent solar panels are installed on buildings. They can be placed on top of windows or even completely replace them, and they work as a complementary source of solar energy production.

However, in reality their potential uses are endless. As technology is perfected, these photovoltaic glasses could be applied to mobile phones or computers, for them to charge themselves, to electric cars, etc.

Are solar windows economically viable?

Although this technology is becoming increasingly well known, there is still a long way to go for them to be a solid alternative to solar panels. This is because they are transparent and let through part of the light waves, meaning energy production is somewhat lower and they are used mainly as a complement to other energy sources. Even so, it should be noted that what they lose in efficiency they gain in quantity, because these photovoltaic windows can be installed in large numbers in buildings, while the space for solar panels is more limited.

Furthermore, since the technology is still fledging, production costs are still too high to be profitable. However, with research and development, photovoltaic glasses could consolidate their position as a solid alternative to conventional solar panels.