Green Colored Solar Panels

Highly rated models of solar panels are now running in excess of 20-percent efficiency at turning sunlight into electricity. But they are bulky and still aren't very pretty. In addition, traditional solar panels take up a lot of room.

Fortunately, solar technology is changing continuously. Earlier this year Tesla began selling solar shingles that can generate power for the home and still look like ordinary shingles. Other solar panel developers have made solar windows, skylights, patio covers, carports, and roads to generate electricity. And now researchers in the Netherlands say they have developed a process for making conventional bluish-black solar panels bright green. Probably the same technology might also make it possible to create panels in other colors, and even in white which would be a really big step in the solar industry. 

Researchers from AMOLF, the University of Amsterdam (UvA) and the Energy research Centre of the Netherlands (ECN) have developed a method for imprinting existing solar panels with crystalline silicon nanocylinders. The nanocylinders are about 100 nanometres wide and exhibit electromagnetic resonance that scatters a particular wavelength of light. They produce the green color by scattering green frequencies of light back while letting other frequencies of light pass through. They are laid down on the solar cells via a process the researchers likened to rubber stamping. The panels have a green appearance from most angles and they are only about 10 percent less efficient than conventional panels.

The method used for the colored solar panels is called soft-imprint lithography. “In principle, this technique is easily scalable for fabrication technology,” AMOLF scientific group leader and senior author Albert Polman said.

Such colored solar panels would afford a level of versatility - for example, red panels could be used on rooftops, white ones on walls, and the green ones could blend in with nature. Thus would encourage the reliance on solar energy and integration of solar technology into every part of our daily lives.

“You have to combine different nanoparticles, and if they get very close to each other they can interact and that will affect the color,” said Polman.

These aren't the first colored solar panels. But the ones already on the market use dyes and reflective coatings that give them their color, greatly reduce efficiency and they are about 45 percent less efficient than ordinary solar panels at generating electricity.

The new design was published online on August 15, 2017, in Applied Physics Letters.

World's Leading Photovoltaic Companies

Sharp Solar is the world's largest photovoltaic module and cell manufacturer, with an overall capacity of 600 megawatts. It manufactures in Japan, in the UK - near Wrexham, and recently opened a large manufacturing facility in Memphis. Sharp Solar produces both single and multi-crystalline solar cells which are used for many applications. Sharp began its development of solar cells in 1959, with mass production first beginning in 1963. In 1980, it was one of the first companies to introduce calculators powered by solar cells.

Established in 1999, Q-Cells is the world's second largest cell manufacturer, based in Thalheim, Germany (Q-Cells AG was the single largest producer of solar cells in 2007 according to industry data). Its core business is the development, production and marketing of high-quality (mono- and multi-) crystalline silicon photovoltaic cells.

Based in Wuxi, China, Suntech Power is the world's third largest producer of photovoltaics in 2007. Suntech Power manufactures solar cells and modules and it is a global leader in solar energy as measured by both its production output and the capacity of its solar cells and modules.

Headquartered in Kyoto, Japan, the Kyocera Corporation is a pioneer in the solar energy market and began to develop solar cells in 1975. Today Kyocera is one of the world’s leading manufacturers of solar cells and modules, with a highly controlled mastery of all the production steps from wafer and cell fabrication to module assembly.

The Phoenix, Ariz.-based First Solar is a leader in the development and manufacture of high quality thin film solar modules. They manufacture photovoltaic solar modules developing advanced, thin film semiconductor deposition and high volume manufacturing processes, based on Cadmium Telluride (CdTe).

Motech is the largest manufacturer of photovoltaic cells in Taiwan. For over 25 years, Motech Industries, Inc. (Motech) has been creating high quality products, from testing and measuring instruments to solar cells. Motech has now become one of the top 10 producers of solar cells and the 6th largest crystalline solar cell manufacturer in the world (2007).

SolarWorld is headquartered in Bonn, Germany, and purchased Shell Solar's crystalline silicon activities in 2006. SolarWorld is one of the three largest solar energy groups in the world. The SolarWorld Group of companies is involved in every step of the solar value chain from raw silicon to turn-key solar power systems and is active in growing solar markets around the world.

Japanese company Sanyo Electric has been manufacturing solar cells and panels since 1970s. In 1992, Sanyo Electric started the practical application of installing the first PV generation systems on individual houses in Japan. SANYO HIT (Heterojunction with Intrinsic Thin layer) solar panels are a leader in cell and module efficiency with models up to 16.2 Watts per sq. foot (17.4% module efficiency). On July 29, 2008 the company announced, that it achieved a cell conversion efficiency of 22.3% at the research level.

China-based Yingli Green Energy is one of the world's leading vertically integrated PV product manufacturers. Yingli Green Energy sells PV modules under its own brand name, Yingli Solar, to PV distributors located in various markets around the world, including Germany, Spain, China and the United States.

SunPower Corporation is a Silicon Valley based solar company, and is one of the largest in existence.The company designs and manufactures high-efficiency silicon solar cells and solar panels based on an all-back-contact "All-Black" design. They install them through their subsidiary PowerLight. Their Nellis Solar Power Plant is currently the largest PV installation in North America

Schott Solar Germany is among the world's leading fully integrated manufacturers of PV wafers, cells and modules. The company has more than 40 years of experience and offers reliable PV solar electricity modules for almost any kind of application. Schott Solar is also one of the leading companies in thin film technologies.

Renewable Energy Corporation (REC) is based in Norway, and was established in 1996. Over a relatively short period, REC has become the world's largest producer of poly silicon and wafers for PV applications. The company has seven production plants in three different countries and customers all over the world.

Mitsubishi Electric is one of the world’s largest manufacturers and providers of solar power technology, including PV cells, modules and inverters. The company’s eco-friendly photovoltaic systems are used throughout the world to bring clean, reliable energy to residences, business, power generation plants, schools, and factories.

BP has been involved in solar power since 1973 and its subsidiary, BP Solar, is now a major worldwide manufacturer and installer of PV solar cells, with production facilities in the United States, Spain, India and Australia. Headquarters for BP Solar are located in Frederick - a city in west-central Maryland, United States.

Isofoton is a Spanish company, the biggest solar panel manufacturer in Europe. The company designs and manufactures high-efficiency mono crystalline silicon cells (also the most expensive), and it is currently the largest mono crystalline producer worldwide.

Nanosolar was started in 2002 and is headquartered in Palo Alto, California. Nanosolar is a maker of thin-film solar panels and is a global leader in solar power innovation. Nanosolar Powersheet, a very thin film solar panel has won the Popular Science Innovation of the Year award. The company manufactures Powersheet by printing a solar absorbing “ink” onto a thin rolled metal sheet in a low-cost, fast, continuous process. The company has manufacturing operations in Silicon Valley, California, and the Berlin capital region, Germany.

Thin-film Photovoltaic (PV) Cells

In some of my previous posts I have mentioned thin-film photovoltaic cells and in this article I'll give a brief overview of them.

Solar panels based on the photovoltaic effect have been used for more than thirty years and have traditionally been built using wafers of crystalline silicon, which requires expensive processing and results in ridged, heavy and fragile solar panels.

Crystalline silicon PV cells are still the mainstream products in the PV cell market because they have high conversion efficiencies. However, their output is increasingly being bogged down by shortage of raw material, high production cost and difficulty of processing. These factors have given rise to rapid development of second generation PV technology known as thin-film PV technology.

Thin-film solar cells are generated by coating a substrate (glass, thin flexible metal or plastic substrate) with layers of conductive and semi-conductive materials of a few micrometers in thickness. The individual layers of material are deposited by various processes.

The key materials for the thin-film solar cells are semiconductor elements such as amorphous silicon (a-Si, still silicon, but in a different form), cadmium telluride (CdTe) and copper indium (gallium) diselenide (CIS or CIGS).

Amorphous silicon (a-Si) was the first thin-film material to be commercialized, although, the PV cells built from amorphous silicon are invariably less efficient than crystalline PV. These PV cells have low efficiency and limited lifetime (approximately 10-15 years). Initially, a-Si was mostly used in consumer items such as calculators. Amorphous silicon is the most widely used for the creation of thin-film solar panels. It has a sun energy conversion rate as high as 9%.

Cadmium telluride (CdTe) is a highly useful material in the making of solar cells. Cadmium telluride PV (CdTe PV) is the first and only thin-film photovoltaic technology to surpass crystalline silicon PV in the marketplace in terms of lower system price for a significant portion of the PV market – large (multi-kW) systems.

CdTe PV cells structure includes a very thin layer of cadmium sulfide that allows most sunlight to pass through to the CdTe layer. These characteristics provide the potential for high-efficiency modules with low-cost manufacturing processes. CdTe cell efficiencies are over 16% in the laboratory; commercial module efficiencies are likely to be in the 9% range in the first manufacturing plants.

Copper indium gallium diselenide (CIGS) cells create more electricity from the same amount of sunlight than does other thin-film PV and therefore has a higher "conversion efficiency". Besides that, CIGS conversion efficiency is very stable over time, meaning its performance continues unabated for many years.

CIGS cells use extremely thin layers of semiconductor material applied to a low-cost backing such as glass, flexible metallic foils, high-temperature polymers or stainless steel sheets. They are of interest for space applications and the portable electronics market because of their light weight. CIGS cells are also suitable in special architectural uses, such as photovoltaic roof shingles, windows, siding and others. CIGS thin-film solar cell recently reached 19.9 percent efficiency, setting a new world record for this type of cell.

Thin-film PV technology has attracted a lot of interest in the recent years. The main reason for this interest is that thin-film PV cells are less expensive than other PV systems. Rather than being manufactured laboriously piece by piece, thin-film can be mass-produced in cheap rolls like packaging - in any colour. Thin-film PV cells also can harvest as much energy from the sun with far less semiconductor material. They can be made with flexible substrates which allow them to be used in more locations than silicon cells, such as clothing and sails. A number of applications are being pursued using thin-film PV technologies, including roof-top applications (such as rooftop shingles, roof tiles), building-integrated photovoltaics (BIPV), the glazing for skylights or atria, and utility-scale applications.

Thin-film PV cells represent the most promising technology for providing more affordable solar cells for residential and other uses in the future. According to NanoMarkets, the thin-film photovoltaics (TFPV) market will produce 26GW by 2015, generating over $20 billion in revenues.