Cutting edge ways to utilise buildings for electricity

Tesla and SolarCity-owner Elon Musk has just revealed their latest product, called the ‘Solar Roof’, which is essentially tiles with integrated, high-efficiency solar cells behind tempered glass.

The new solar tiles are stylish as one can choose the most matching look for any building from the four different styles available (textured glass, slate glass, Tuscan glass, smooth glass tile). By using glass, the durability of tiles is increased and might even outlast the building’s life as claimed. There is a slight loss of efficiency (they work at 98 per cent), but the company is working on improving this rate.

Tesla claims the new roof could be more affordable than conventional ones when calculating utility costs as well, and when bundled with Tesla’s Powerwall ‘personal battery solutions’, households of the future shall be able to generate most of the power they would use.

Meanwhile researchers are also working on how to utilise windows to generate electricity. Scientists at the Los Alamos National Laboratory, New Mexico, have published a paper in Nature Energy claiming that a thin film layer of ‘quantum dots’ added to existing windows could enable low-cost window-based solar photovoltaic (PV) systems, which could reach higher efficiency (up to six per cent) than current systems. Quantum dots are nanometre-sized semiconductors, which enable scientists to set which type of light is absorbed. The layer is easy to apply, and the silica-protection protects against oxidation, for enabling durability.

Photos: Tesla Solar and Los Alamos National Laboratory, New Mexico

See-through solar cells

Solar cells are mostly thought of as covering a roof or a large field of reflective solar panels in the middle of the desert. But recently researchers at Michigan State University developed a solar cell that is transparent, and so could bring amazing possibilities. Being transparent means that these cells could be used in many more places than traditional solar cells – including windows and other glass surfaces like phone screens – without interruption to doing their job of collecting the sun’s energy. 

As the basic principle of solar cells is to absorb the sunlight in order to turn it into electricity hence shouldn’t let it through (which means they shouldn’t be transparent), this novel solar PV cell in fact is a so-called transparent luminescent solar concentrator (TLSC). It includes special organic salts than can transform certain types of non-visible wavelengths of light (UV and infrared) into a different type of non-visible light (also infrared) and this is then beamed to the traditional solar PV cells located on the rim of the solar cell.

The current efficiency is about one per cent (with expectations to increase it to five per cent) but it can be scaled up when applied at building windows, or it could be used to extend the battery life of mobile devices.

Prior similar solutions were mostly coloured, but the new technology allows them to be fully transparent, opening up a range of new surface options.

Michigan State University scientists are not the only ones trying to utilise large glass surfaces.

SolarWindow Technologies took another approach by having developed a see-through liquid coating that can be applied to glass that can harness solar energy. The materials used are organic, offer great performance and it’s claimed to be working well even in shaded areas and in artificial light!

Ubiquitous Energy is another company focusing on the development of transparent solar cells. Their solution technology is a film that lets visible light through but filters and absorbs ultraviolet and near-infrared light, which it turns into electricity. They claim that the efficiency can be more than ten per cent.

With so many different approaches to the same idea, see-through solar cells might be here soon.

Image credit: Michigan State University

What is Thermoelectricity?

Thermoelectricity means to gain electricity directly from the heat difference of two parts of a material – and it can also work in reverse. This means that by introducing an electric current, the material could be either heated or cooled down. The technology has already been used for power generation in spaceships, and the reverse is applied for heating car seats, food carriers or computer chips.

One of the main challenges of thermoelectricity is to find the right material. The perfect material should conduct electricity well but not heat, in order to work appropriately. This is rather hard to find and so nano-scientists have been working on solving this issue. A Norwegian team for example recently introduced nanoscale-barriers into common semiconductors, which helped them in lowering heat conductivity, while keeping the electronic conductivity – just what’s needed for utilising thermoelectricity.

Thermoelectric materials may be ideal for ‘replacing’ current photovoltaic (PV) cells, according to some scientists. This would be thanks to the fact that they can utilise a much broader spectrum of solar energy, and thus they could provide better performance. A Professor from the University of Arizona recently suggested that thermoelectric paint on top of roofs with solar panels could be applied to achieve better performance and eventually for lowering costs.

Thermoelectricity could also be a great solution for using up waste heat. Waste heat is the energy created by machines that is not utilised for anything. According to estimates this is currently about half of all energy in the world, and is generated by industrial processes, combustion engines and power generation, amongst others.

Thus if the right materials are identified or created thanks to nanotechnology, thermoelectricity could be one of the key future technologies, which could help in various fields.

Written for the Energy Saving Warehouse

Plastic Solar Cells

While the cost of solar panels in general is decreasing, the main material solar cells are made of may become scarce in the future. This is silicon, and it’s in high demand as it’s used in many industries – for instance at the manufacturing of computer components or for waterproofing treatments. Scientists have however announced the development of the first plastic solar cell. Is this maybe a solution for the future?

The Center for Organic Photonics and Electronics at Georgia Tech has discovered a new method for printing electronics. The process itself is not new as it has been used at organic solar cells or OLEDs but until now the manufacturing stage was more problematic due to potential chemical reactions by the metals that have been used. The new technique could solve the issue by applying a thin layer of polymer on the surface of the conductors, which will chemical reactions and does not need an extra layer of protection. Thus the manufacturing process can become more stable, and as electronics can be printed onto plastic, it shall become cheaper and easier. And also the polymer used is cheap, easily available and environmentally friendly.

Earlier, researchers at the University of California developed a polymer solar cell, which efficiency exceeded even those made of silicon. It features two layers of plastic that react to different bands of light: visible and infrared, which enables the increase of efficiency.

Konarka Power Plastic usage

Konarka already offers its solar product, Power Plastic, which is thin, flexible and comes in various colours – including transparent design. They have been specially applied on bags or on various surfaces, like carport tops or tents.

Another company, Solarmer Energy has also developed an organic plastic solar panel, with several great features that offer new fields of application, including portable electronics, smart fabrics and buildings.

Polymer solar cells are not only thin and light, but their low cost could mean a significant price drop for this market, and researchers are already working on the manufacturing challenges.

Written for the Energy Saving Warehouse

Image: Konarka