Solar Power Stations in Space - Science Fiction or a Future Reality?

                  Image credit: solarspacetechnologies.com.au

Solar power stations in space or the so-called space-based solar power (SBSP) concept means capturing solar power in outer space and distributing it to Earth. In 1941, science fiction writer Isaac Asimov first wrote about space-based solar power stations in the short story “Reason”. Later, American aerospace engineer Peter Glaser wrote the first technical article on the concept – Power From The Sun: Its Future, and it was published in the journal “Science” (1968). 

Generating solar power in space has many advantages. As we know, the Earth’s atmosphere absorbs and reflects some of the Sun’s light. A considerable fraction of incoming solar energy (55–60%) is lost on its way through the Earth's atmosphere. So, solar cells above the atmosphere will receive more sunlight and produce more power as the Sun always shines in space. An orbital solar power station will be an inexhaustible source of clean energy.

One of the major challenges will be getting the power transmitted back to Earth. The idea is to convert electricity from the solar cells into microwaves or lasers and transfer them down to an antenna on the Earth’s surface. The antenna would then convert the waves back into electricity. 

Recently, the UK government reveals an ambitious new plan for a space-based solar power station that could collect solar energy and beam it down to the UK. According to it, giant solar power satellites in orbit could harvest solar power and transmitting it as high-frequency radio waves to ground-based receivers connected to the electrical power grid.

The big question is how to launch such large structures into space. One possible solution is to develop many smaller satellites that could easily connect in space to form a single solar power station. In 2017, researchers at the California Institute of Technology created a prototype for a modular power station, using thousands of ultralight solar cell tiles. 

Another related news is that researchers at the University of Liverpool are working on a project to design and manufacture low-cost, ‘origami’ deployable structures consisting of thin-film photovoltaic cells incorporated onto a sail. A swarm of photovoltaic solar sails could be configured in-space to provide large-scale and versatile Space Solar Power (SSP) energy generation. 

Also, the Australian-based company Solar Space Technologies, working in partnership with US-based Mankins Space Technologies, Inc. (MSTI), is planning to develop, manufacture, deploy and operate a solar power satellite (called SPS - ALPHA) into geostationary orbit to supply baseload energy to the Australian grid by 2027. SPS-ALPHA was first-examined under a NASA Innovative Advanced Concepts (NIAC) project (2011-2012). The newly proposed solar power satellite has been re-designed to be made up of many repeatable building blocks that can be assembled in space instead of manufacturing one, expensive, single large system. This approach makes the cost of building the platform much lower than if traditional satellite building approaches were. SPS- ALPHA platforms are sized to deliver 2.1 GW each at a levelized cost of electricity (LCOE) of 5¢ per kilowatt-hour ($, US) over a 30-year nominal lifetime. 

Researches in Japan led by the Japan Aerospace Exploration Agency have been working on a project to build a space solar power station for a long time. They have already developed designs and demonstrated solar power satellite of sandwich type.

In my post “Solar energy interesting facts” I have mentioned that China has designed a space solar power system, which they aim to have operational by 2050. This system should be capable of supplying 2GW of power into Earth’s grid at peak performance. 

It seems that scientists are already much closer to construct solar power stations in space. Currently, we are reliant on materials from Earth to build power stations but maybe one day we can use resources from space for manufacturing, such as materials found on the Moon.

The concept for constructing a space solar power station has fantastical origins but it is now being researched by several nations and many scientists around the world are working on it. Thanks to rapid advances in lightweight solar cell tiles and wireless power transmission technology it may become a future reality sooner than we could imagine.

Sources: wikipedia.org, bbc.com, imeche.org, solarspacetechnologies.com.au

Solar Panels for Your Home - How to Choose The Best

Solar panels are the most essential components of the solar power system. To choose the best solar panels (also called solar modules) is the most important thing for every homeowner who has decided to go solar. In this post, you will find some directions on how to choose the best solar panels for your home.

First of all, you have to choose the type and the brand of solar panels. There are four key technical specifications you have to consider: panel efficiency, temperature coefficient, the materials warranty, and the performance warranty. 

There are two main types to choose from when it comes to solar photovoltaic panels: monocrystalline solar panels and polycrystalline solar panels. Monocrystalline solar panels (black color) are more efficient because they are manufacture from the purest silicone. Each solar cell here is cut from a single, continuous piece of silicon crystal. Monocrystalline solar panels are also more expensive. They cost between $300-700 USD per panel. Monocrystalline solar panels produce the most waste when they're manufactured. 

Polycrystalline solar panels (dark blue color) are considered to be less efficient and this is due to the method of production. Manufacturers melt multiple silicon fragments together to produce the wafers for this type of solar panel. They are the most commonly purchased solar panels, simply because they are the most affordable option. Polycrystalline solar panels usually cost between $200-500 USD per panel. They are an environmentally-friendly option because they utilize all of the silicon material they are manufacture. 

There is also another type of solar panel - thin-film solar panels. Thin-film panels are cost-efficient and most sustainable to produce and they are least expensive. However, they are also the least efficient (commercially available generally have efficiency in the 10–13% range) and degrade faster. Thin-film panels need more space, even twice as much room as a mono- or polycrystalline solar panel with the same energy output. These types of solar panels usually cost between $175-300 USD per panel. It is rare to see thin-film panels on the roof. Thin-film photovoltaic cells are used for large and small PV application such as a calculator, solar-powered charger for smartphones, solar-powered purse, solar-powered backpack, curved surfaces on buildings and cars, even on clothing to charge small electronic devices. They are also used to power traffic and street lights, and for commercial and industrial projects (solar farms).

You may have heard about bifacial solar panels, which can absorb light on both the front and the back of the panel. They have higher rates of power output and higher efficiency than traditional solar panels. But these types of solar panels aren’t typically used for residential solar installations. They are more expensive and they are more suitable for large ground-mounted projects.

The second thing to consider is the brand. Some of the best quality and most reliable panel manufacturers are LG, SunPower, REC, Solaria, Panasonic, and QCells. You can see the list of the best manufacture at Top 10 Solar Panels - Latest Technology 2020 — Clean Energy Reviews. Another review of solar panels you can find at Best Solar Panels in 2020 [Complete List] | EnergySage. The best brands of solar panels have the best solar panel efficiency and temperature coefficient.

Solar panel efficiency means the percentage of sunlight that hits the surface of solar panels converted into electricity for your home. Currently, most solar panels have an efficiency between 15% to 22%. The average efficiency of solar panels is between the 17% to 19% efficiency range. The higher the efficiency rating, the more sunlight your solar system can turn into electricity to power your home. SunPower’s A-Series Residential Solar Panels are 22.8% efficient at their maximum and they are the best solar panels available on the market today. Keep in mind, however, that efficiency also depends on factors like placement, orientation, shading, time of year, dust and dirt, weather conditions, etc. If you have enough roof space you may choose less efficient and not so expensive solar panels.

The temperature coefficient tells you how well your solar panels will work on hot summer days. Solar panels operate most efficiently when they are kept cool (ideally around 25° C or 77° F panel’s temperature). The temperature coefficient usually ranges between -0.3% and -0.5 %/°C. Solar panels are tested according to international technical standards at 25°C, and that is why this is used as the reference point. For every degree above that temperature, your solar panel’s electricity production will decrease by the temperature coefficient. If the temperature coefficient is -0,3% and your solar panel’s temperature increases by one degree Celsius (from 25° C to 26° C), its electricity production will fall by 0.3%. If the temperature increases ten degrees Celsius to 35° C (or 95° F), the panel will produce 3% less electricity. So, a lower temperature coefficient is better. The temperature of the panels depends on your location, roof material (some absorb more heat than others), and the installation of the panels (if they are angled or mounted flat on the roof). In many instances, a solar panel’s surface can get as hot as 50° - 65°C. If the installation is a typical rack-type, you will have a gap of greater than 150mm between the roof surface and the panels. It will allow airflow to have a cooling effect on the panels.

Thin-film solar panels have a lower temperature coefficient than traditional monocrystalline or polycrystalline panels. Their temperature coefficients are closer to -0.2% / °C.

Another important thing is a solar panel’s materials warranty which protects against failure due to manufacturing defects. Solar PV manufacturers provide a minimum 10 - 12 years product warranty but many solar panel manufacturers offer 15, 20, and even 25-year product warranties. This means the manufacturer must either replace or give you a refund for solar panels that fail within the product warranty period.

The performance warranty is different from the solar panel’s materials warranty. The performance warranty is called also the 'power output warranty' and it ensures that the solar panel still produces a minimum power output after a specific amount of time. The common industry standard is 80-83% power output after 25 years. Some top manufacturers such as SunPower and LG guarantee 88-92% power output on most modules after 25 years of use.

Besides the top solar panel brands, many manufacturers are offering a wide range of quality, affordable panels. The most well known of these manufacturers are Jinko Solar, Canadian Solar, and Trina Solar. See other brands at Choosing a quality Solar Panel - Reliability, warranty and efficiency — Clean Energy Reviews

And finally, to determine the number of solar panels you need to do some calculations regarding current energy consumption in your home, and how it will change in the future.

When you choose your solar panels it is important to know, that a solar power system is a complex system of several components and the overall performance depends not only on solar panels. All components should be compatible with each other (solar panels, solar inverter, battery storage, charge controller). Also, the homeowners should carefully consider their unique house and household circumstances and maybe even seek the advice of an expert before choosing the right solar panels for their home. 

Sources: wikihow.com, cleanenergyreviews.info, energysage.come & Internet

Read also: Basic Things to Consider Before Buying a Solar Electric System
                   Applications of Photovoltaic PV Power Today

Solarpro’s Yankovo PV Power Plant Put into Operation

On 24 August the first stage of the photovoltaic plant of Solarpro in the village of Yankovo, northeastern Bulgaria, has been officially put into operation. The first phase of the project "North-East 1" features installed capacity of 338kWp . The plant had been successfully acceded to the power grid of E. ON and delivers electricity to the electricity distribution company. The project is scheduled to reach full capacity by the end of the year. The whole plant "North-East 1" has nominal power of 2404kWp will be the largest photovoltaic park in the country.

Solarpro, 80% owned by Bulgarian miner Kaolin, has launched production of photovoltaic (thin-film amorphous-silicon PV module) solar panels at its factory in Silistra, on the Danube. At the end of March the first panels of the first production line of the photovoltaic plant in Silistra were produced.

The "North-East 1" PV power plant is constructed with 8064 thin-film photovoltaic panels, manufactured by Solarpro, in its Silistra-based factory. It is the only company in Bulgaria, which concludes the entire PV module manufacturing – power plant integration chain. The components of the power plant are mainly made in Bulgaria, and all subcontractors are local companies.

Solarpro is the first and only manufacturer of solar panels in Bulgaria. Solarpro is the biggest solar panels manufacturer on the Balkans, with planned capacity of 18 MW annually, organized in three production lines, one of which currently operational. The company came into being in end-2007 in line with a strategy of its owner to bolster energy efficiency and reduce dependence on fossil fuels.

Sources: solarpro.bg & alfafinance.bg

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.