California Nearing Huge Milestone in Solar Deployment

seia_logoWASHINGTON, D.C. – California has cemented its place as America’s solar leader, according to the recently-released U.S. Solar Market Insight 2014 Year in Review, and stands poised to become the first state in the nation to have 10 gigawatts (GW) of installed solar capacity, enough to power nearly 2.5 million homes.

In 2014, California added 4,316 megawatts (MW) of solar electric capacity, bringing its total to 9,977 MW – just 23 MW short of cracking the 10 GW barrier. The report went on to point out that California had big increases last year across all solar sectors. Of the new capacity added, 615 MW were residential, 307 MW were commercial and 3,395 MW were utility scale. Together, these installations represented an $11.7 billion investment in the state.

“When it comes to creating clean energy jobs and protecting the environment, California is leading by example,” said Rhone Resch, president and CEO of the Solar Energy Industries Association (SEIA). “To put the state’s remarkable progress in some context, today California has 10 times more installed solar capacity than the entire nation had in 2007. We congratulate Gov. Brown, his administration, legislative leaders and the people of California for being the ‘little engine that could’ and demonstrating to America the viability, as well as the reliability, of clean, affordable solar energy.”

California’s notable 2014 projects include:

Desert Sunlight, which was recently completed by developer First Solar. This photovoltaic (PV) project has the capacity to generate 550 MW of electricity – enough to power more than 160,000 California homes.
At 250 MW, Mojave Solar is also among the largest solar installations in California. Completed in 2014 by Abengoa Solar, this concentrating solar power (CSP) project has enough electric capacity to power more than 61,000 homes.
Many large retailers in California also installed solar installations last year, including Walgreens, Johnson & Johnson, Walmart and IKEA.
Campbell’s Soup installed one of the largest corporate PV systems in the state with 2,300 kilowatts (kW) of solar capacity at their location in Sacramento.

The residential market also continued to flourish last year, with installed system prices dropping again – and down a total of 49 percent since 2010. The upswing in residential installations is expected to continue in the foreseeable future, especially in light of a new report by the California Energy Commission, which shows that more than a quarter of all new homes being built in Southern California are being constructed with solar energy systems. Presently, there are more than 2,000 solar companies at work throughout the value chain in California, employing 54,700 people. These companies provide a wide variety of solar products and services ranging from solar system installations to the manufacturing of components used in PV panels.

From an environmental perspective, solar installations in California are helping to offset more than 11.7 million metric tons of harmful carbon emissions, which is the equivalent of removing 2.5 million cars off state roads and highways.

“Today, the U.S. solar industry employs 174,000 Americans nationwide – more than tech giants Apple, Google, Facebook and Twitter combined – and pumps nearly $18 billion a year into our economy,” Resch added. “This remarkable growth is due, in large part, to smart and effective public policies, such as the solar Investment Tax Credit (ITC), Net Energy Metering (NEM) and Renewable Portfolio Standards (RPS). By any measurement, these policies are paying huge dividends for both the economy and environment.”

Stacking Solar Cells Could Vastly Improve Their Efficiency


Harvesting solar energy is a great way to generate sustainable power, but unfortunately solar cells are far from being as efficient as they might be. Currently, commercially available solar cells can convert about 25 percent of sunlight into electricity, and scientists have been trying to create better solar cells for years. One milestone they have been unsuccessfully trying to reach is 50 percent conversion efficiency of solar cells. However, the start-up company Semprius might be on the right track with the stacking technique of solar cells they recently developed.

The idea to stack solar cells in order to make them more efficient is not entirely new, but Semprius has managed to make a huge leap forward with it. They have successfully demonstrated that three semiconductor materials can be stacked on top of a fourth solar cell. Such a stacked device is capable of reaching efficiencies of up to 44.1 percent. Furthermore, this stacking technique allows for the reuse of costly crystalline wafers that multijunction solar cells are grown on, which significantly reduces production costs.

The three key innovations of the technique developed by Semprius are a cheap, fast way to stack cells, a proprietary way to electrically connect cells, and a new kind of glue holding the cells together. The design of Semprius’ stacked solar cells utilizes tiny individual solar cells, each of which measures only a millimeter across. This also helps to bring down the costs while improving efficiency.

The company is certain that in three to five years, they will be able to construct solar cells that will consist of two stacked multi-junction devices, which would yield a total of five or six semiconductors. Such a device could actually surpass the magic 50 percent solar cell efficiency point.

Also, such cells would have a manufacturing capacity of 80 to 100 megawatts a year, and solar cells that can achieve 50 percent efficiency could potentially reach costs of five cents per kilowatt-hour. This is less than the current price of natural gas, which costs 6.4 cents per kilowatt-hour.

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More Environmentally Friendly Solar Cells


Researchers at Northwestern University have developed a new solar cell that uses tin instead of lead perovskite as a collector of solar energy. This cheap and environmentally-friendly solar cell can therefore be made without any high-tech equipment or hazardous materials.

The new solar cell developed by the team uses a structure called a perovskite and utilizes tin instead of lead as the light-absorbing material. Lead perovskite is a solar cell material that can convert up to 15 per cent of sunlight to electricity, which is very close to the efficiency of the current solar cells. The team developing the new cells is certain that tin perovskite should be able to match or even improve on that result.

These new cells are the brainchild of lead researcher Mercouri G. Kanatzidis, who first developed, synthesized and analyzed the material. Afterwards, him and nanoscientist Robert P. H. Chang from Northwestern worked together to engineer a usable and efficient solar cell from the material. The tin-based perovskite layer of the new solar cell acts as an efficient sunlight absorber and is placed between two electric charge transport layers for conducting electricity.

The solid-state tin solar cell is a sandwich of five layers, with each layer contributing to the effectiveness of the cell. The first layer is electrically conducting glass that lets sunlight enter the cell. The next layer is composed of titanium dioxide and is deposited onto the glass. Together these two layers form the electric front contact of the solar cell.

After this, the tin perovskite (that is the light absorbing layer) is deposited, which is done in a nitrogen glove box to avoid oxidation. Next comes the hole transport layer, which is needed to close the electrical circuit and produce a functional cell. The final step is applying a thin layer of gold caps and the resultant solar cell is only about one to two microns thick. These cells achieved energy conversion efficiency of 5.73 percent in tests done with simulated full sunlight.

Since currently used solar cells are not made in a very environmentally friendly way, it is great to see scientists trying to solve this problem. Sure, translucent solar cells may be the future, but affordable solar energy harvesting solutions that can be developed and put on the market in the next few years are equally, or perhaps even more, welcome.

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Innovative Ways of Using Solar Panels

Photo: Mineirão stadium in Belo Horizonte

The photovoltaic technology is frequently used to obtain energy these days. Since it was discovered in the 19th century that it is possible to get energy from sunlight, the ways of harnessing solar energy went through many different stages. The first prototype of solar cells was, for example, used to provide the satellite Vanguard I with energy in 1958 and the technology has been used in this area ever since.

The oil crisis demonstrated our dependence on fossil fuels and led to the much needed rethinking of where the energy comes from with a view towards finding dependable sources of renewable energy. Coupled with the nuclear power plant catastrophes and a stronger environmental consciousness also stimulated this wish to use nonpolluting and sustainable sources of energy. Therefore many enterprises and households opted for solar energy, since solar panels can be easily installed on rooftops, where they can harness energy from the sun, which is a limitless source of renewable power. Due to the greater interest and demand it is also important to consider the Solar IRR, solar economic return projects, among others.

Lately, this technology has developed much further than the known uses of solar panels on rooftops and on the ground. One such example is the building of integrated photovoltaics. During World Cup 2014, the company Martifer presented their completed project of a 1.4 MW installation of solar panels on the rooftop of the Mineirão stadium in Belo Horizonte, Brazil. The match on June 14 was the first one ever played in a stadium that obtains its energy from solar panels.

Mineirão stadium was fitted with 6,000 solar panels, and it is the first ever World Cup stadium to be powered entirely by solar energy. This solar power array is capable of producing 1,600 megawatts-hours of electricity per year, which is enough to power 1,200 households. About 10 percent of this electricity will be used in powering the Mineirão stadium, and the rest will pass back into the grid and be used by consumers.


Build Your Own Underground Greenhouse


Growing food in the colder months of the year is a challenge, and growers in colder climates that want to extend the crop-growing season are always looking for a better way to do so. Greenhouses are a great option, but they cost a lot of money to construct and heat during the colder months. The American sustainable agriculture non-profit organization Benson Institute has come up with a set of easy to follow instructions on how to build a much cheaper alternative, the so-called walipini, which means “place of warmth” in Aymara Indian. The walipini is basically an underground, pit greenhouse in which it possible to grow vegetables all year, even in the coldest regions of the world.

The walipini is built using the principles of earth-sheltered building and passive solar heating. The Walipini is basically a rectangular hole in the ground that should be 6 to 8 feet deep. Once the hole is dug, it should be covered by plastic sheathing. The longest side of the rectangular hole should face the winter sun, which is to the north in the Southern Hemisphere and to the south in the Northern Hemisphere. At the back of the structure, there should be a thick wall of rammed earth, while at the front there should be a much lower wall, which provides the ability to angle the plastic roof in the correct fashion.



The roof serves two functions, namely to protect the plants and to heat the greenhouse. The plastic roof is made up of two layers of plastic, namely a sheet on the top and one on the bottom of the roof/poles. It works to seal the hole in the ground, and creates an insulating airspace for the garden. In addition to that, it lets in the sun’s warmth and traps it, which creates an even temperature inside the walipini and allows for successful year-round vegetable growth.

By being built underground, the walipini also takes advantage of the earth’s thermal mass, meaning that a lot less energy is needed to heat up its interior compared to a conventional greenhouse. The structure must of course be waterproofed and ventilated correctly, face the sun at the right angle and have an adequate drainage system. The Benson Institute has a detailed manual on the construction process available here.



The Benson Institute built a 20-foot by 74-foot field model walipini in La Paz, Bolivia, which they say, cost only about $300 to build. The low cost is due to volunteer labor and using materials such as plastic ultraviolet (UV) protective sheeting and PVC piping, which are very affordable.

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