Wall, tile, butterfly – four crazy solar ideas reveal the boom in photovoltaics

Solar energy is doing better than ever before. The “Solar Package I” will bring significant relief not only to large solar parks, but also to small solar panels on your own roof and balcony. According to a survey by the German Association of Energy and Water Industries, solar energy already contributes around twelve percent to Germany’s net energy supply. In addition, there will be a “record increase in
Photovoltaics”.

One possible reason: solar modules are becoming cheaper and cheaper, especially due to increasing supplies from China. China's share of all manufacturing stages of solar modules – from cells to modules and polysilicon – is currently more than 80 percent, reports the International Energy Agency (IEA).

But what if there is no large, free space for a solar system in the area? In order to install even more solar systems on the earth's surface, various start-ups and institutes have exciting solutions and concepts ready to pave the way for solar energy in the future.

1) Solar cells in the ground

Anyone who does not want to install their photovoltaic system in a visible place will soon be able to simply integrate it into the floor. For example, the Spanish start-up “Solum” has developed a module that can be used directly as flooring, reports “PV Magazine”. It is also conceivable that it could be used in footpaths or cycle paths, with the energy generated being able to directly power the path lighting.

The surfaces are non-slip, can withstand high temperatures of 60 degrees Celsius and are expected to pay for themselves financially after just a few years thanks to their similarly high efficiency. According to Greentechmedia, concepts from the past often failed because their own cooling and environmental road surfaces such as a thick layer of snow significantly reduced the energy actually generated. It remains to be seen whether the new technologies will also be convincing in practice.

Wattway, a project by the French road and rail construction specialist Colas, also wants to score points as “the first photovoltaic road surface in the world”. Here, too, the actual solar cell is embedded in the ground under a reinforced layer of glass. The concept is already being used in many places in France.

For example, in a cycle path to ensure the operation of its surveillance camera. Or even a bridge underpass that powers its own lighting. A Lidl branch in the French municipality of Moult-Chicheboville is already using Wattway in its parking lot. According to Wattway, the solar modules there are said to have generated electricity “for 7,000 hours of use of five supermarket checkouts” in one year. Unfortunately, Lidl did not respond to inquiries from FOCUS online Earth.

+++ Don't miss any more climate news – subscribe to our WhatsApp channel +++

2) Noise protection via solar wall

The Fraunhofer Institute is currently researching the possibility of equipping the noise barriers on German motorways or railway tracks with solar cells. The so-called “PVwins project” is intended to test whether and how photovoltaic systems can be sensibly integrated into existing noise barriers or built as new ones.

The structures must ensure both high energy generation efficiency and effective noise suppression for nearby residents. Finally, the builders of a solar noise wall must also take into account the shading from surrounding trees and the local connection to the power grid. The Fraunhofer Institute also wants to take aesthetic and economic aspects into account and is testing five different variants.

When asked by FOCUS online Earth, project manager Jacob Forster was unable to provide a final evaluation of the measurements, but he was optimistic: “For us, the noise barrier is a great success, as we can show that there are a variety of possible concepts for how photovoltaics can be implemented in different applications.” In addition, such public infrastructure areas could “take on an important role model function.”

The first providers have already put predecessors of the Fraunhofer project into operation, including in the towns of Neuötting (BY) and Waltershofen (BW). The manufacturer Kohlhauer reports that its Volta project will achieve peak outputs of “up to 300 kilowatts” over a distance of around 400 meters. The company has already had positive experiences with solar noise barriers and is convinced that they will also “make a significant contribution to achieving national and international climate goals,” according to a spokesperson.

So far, however, solar noise protection is still the exception and has a “pilot character,” Forster admits. It will therefore probably take some time before solar noise protection is integrated into large parts of the German transport network.

3) Solar modules as home privacy screens

The use of photovoltaics as a wall is not entirely unknown in the private sector either. Some manufacturers already offer so-called solar fences. These not only enclose your garden, but the hedge replacement also produces electricity.

But the orientation is particularly important. The fences are already effective in the south, write the experts at Solarwatt. However, it is particularly useful to set them up in the east or west. The low sun then ensures particularly direct radiation and thus high electricity production. Anyone who opts for so-called bifacial solar fences, i.e. solar fences with modules on both sides, can expect high performance.

According to Solarwatt, the yield with a normal nominal output of between 600 and 750 kWh is around a third lower than that of the average German solar system. However, the fence structures are particularly impressive with the low sun even in winter.

“I actually see the vertical orientation as an advantage in some cases,” says solar expert Forster to FOCUS online Earth. According to him, they are more useful for the grid and are more suited to the times when energy is needed in private households. In addition, photovoltaic fences benefit from better ventilation and, thanks to the affordable modules, would cost about as much as a fence with glass or acrylic elements.

However, shading, for example from parked cars or trees in front of the fence, is likely to cloud the result, especially without bypass diodes in the solar module.

4) Colorful hustle and bustle in the solar business

Fortunately, solutions to this problem are already in the works. The Fraunhofer Institute is currently working on colored photovoltaic modules. These are to be coated with a thin, so-called Morpho-Color layer, for which the institute was inspired by the Morpho butterfly, also known as the sky butterfly.

It owes its bright blue color to an optical trick. Small grooves on the butterfly's scales reflect blue light waves in particular, which means the color does not fade over time. A desirable property for expensive solar modules.

“Their special layer structure enables very high color saturation and exceptionally good angular stability,” the institute writes in a brochure. Solar cell technology behind the color layer remains invisible, but there are also semi-transparent designs.

The efficiency of the brightly colored modules is a particular challenge for researchers. The black coloring of classic solar systems is not a coincidence – they reflect much less sunlight than white surfaces, for example. The brighter the system, the more difficult it is to generate energy. According to the Fraunhofer Institute, however, the loss is currently “only about seven percent.”