Solar Christmas Lights for a Greener Christmas

In accordance with the Holiday Spirit this post is all about having an environmentally friendly and green Christmas just by purchasing a set of outdoor solar Christmas lights to illuminate your home.

Solar Christmas lights can help you save electricity and money, and they are convenient to use because they don’t have to be plugged in and there are no wires to worry about. Solar Christmas lights use LED or Light Emitting Diode technology instead of filament bulbs, which not only saves power and creates vivid light, but also stays cooler than typical bulbs and thus eliminate danger of fire.

When buying Solar Xmas lights you should be aware of charging times and lighting times. On average the outdoor solar lights will illuminate for about 7-8 hours while a few brands tout 12 to 15 hours of illumination time. Keep in mind that illumination time is affected by how fully the solar panel is recharged during the day. Also, an exceptionally cloudy, dark day will reduce the nightly illumination time.

Solar Christmas lights are becoming very popular, which has led to increased availability and design choices. They are available in many different shapes such as stars, bells, hearts, snowmen, snowflakes, Santa designs, and more.

If you want to impress your friends and neighbors you may look for some really impressive solar Christmas lights - those that come with a remote control and with options that allow you to create your own light show. Some solar Christmas lights even let you change the level of light output or change the color of the lights with the remote control.

So, buy a set of cool energy efficient solar Christmas lights and enjoy a Greener Christmas with your family and friends!

Estimate Your Roof's Solar Potential with RoofRay

Speaking of useful online tools, I should mention also a solar array modelling service, provided by RoofRay on their homepage. They use Google Maps and various other information to help you estimate the solar potential of your home or business before taking the financial plunge to invest in solar energy.

Using the site's modelling tools, you can evaluate how much solar energy your home could capture and how that would affect your monthly bills based on past weather conditions, current electricity bills, the slope of your house, as well as how many panels your roof can hold.

With Google Maps you can calculate the square footage of your roof and build virtual panels. Then RoofRay estimates the output potential of the roof, costs of installation, and ROI. Another section shows existing installations that have already been completed by other people, including specifics of the roof used and total peak power.

Of course, RoofRay does not replace solar experts, but undoubtedly could answer some of your basic questions, and generally it is a quite interesting online service that deserves our attention.

Website: www.roofray.com

Updated 2021: Seems like this site is not working anymore, so you can try:      Solar Calculator (solarreviews.com),  SUNSEI Solar Design Tool & Google Project Sunroof

Solar Power Calculating Tools Online

There are a lot of online solar power calculating tools that can help you size your solar power installation. These tools are great in order to determinate how much solar power you'll need to run your home appliances.

NREL's PVWatts® Calculator - Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations.

Off-Grid Solar System Calculator - Wholesale Solar custom designs Off-Grid Solar Home Power Systems. Calculate your appliance needs, get an approximate system size, learn what Off-Grid system is best for you!

CalculationSolar.com - free online platform, which perform calculation of photovoltaic solar installations anywhere in the world.

Solar Calculator (EnergySage) - Use this solar panel calculator to quickly estimate your solar potential and savings by address. Estimates are based on your roof, electricity bill, and actual offers in your area.

Solar Calculators (altE) - a number of useful tools to help estimate your electricity usage, sizing for your grid-tie or off-grid solar power system and more.

Solar Panel (Power) Calculator - online tool used in electrical engineering to estimate the total power output, solar system output voltage and current when the number of solar panel units connected in series or parallel, panel efficiency, total area and total width.

Photovoltaic power calculator - quick online calculation of solar photovoltaic power and energy (PV panels or systems).

Solar Power Calculator - this tool will help you determine the yearly savings you will earn when installing  a PV solar system for your home.

PV Calculator | PVshop.eu - PhotoVoltaic calculator for grid connected and PV off-grid systems in PVshop.eu. (EU)

Solar Energy Calculator | Energy Saving Trust - use the Solar Energy Calculator for an idea as to the benefits you may see from installing a solar PV system. This tool gives estimates based on information you provide, and a number of assumptions to indicate potential benefits. This is to help you decide whether a PV system is for you. (UK)

Solar Power Calculator   - an independent resource for calculating your solar power requirements and potential monetary savings. Find out if solar is right for you. (AU)

Amp & Watt Hour Calculator & Solar System design Tool - This Amp &Watt Hour Calculator is provided to help you make some basic electrical calculations and design your own solar power system. (AU)

Keep in mind that the above calculators are useful as a general guide for sizing your solar electricity system and you probably will also need advices and help from professionals.

Calculating Your Solar Power Requirements

One of the most important thing you have to figure out when planning a solar power installation is the size of the solar system you’ll need.

First of all you need to calculate how much power you use on a daily basis. Your electric bill will be of help for this or you can make your own calculation. The power consumption of appliances is given in Watts (eg 21" fluorescent light, 13W). To calculate the energy you will use over time, you have to multiply the power consumption by the hours of use.

The 13W light fitting, on for 2 hours, will take 13 x 2 = 26WH.

Repeat this for all the appliances you wish to use, then add the results to obtain your daily power consumption.

You have to determinate also how much energy your battery can store. Battery capacity is measured in Ampere Hours (Ah). Convert this to Watt Hours by multiplying the Ah figure by the battery voltage: for a 20Ah, 12V battery the Watt Hours figure is 20 x 12 = 240WH.

The more energy you take, the faster the battery discharges. Keep in mind, however, that deep cycle batteries which are usually used in solar power systems, should not be discharged beyond 50% of their capacity. i.e. 50 % capacity remaining. Discharging beyond this level will significantly reduce the life of the batteries.

To calculate the energy your solar panel can supply to the battery, multiply Watts by the hours exposed to sunshine, then multiply the result by 0.85 (factor to allow for normal system losses).

For example, the Solar 40W panel in 4 hours of sunshine, 40 x 4 x 0.85= 136WH. This is the amount of energy the Solar panel can supply to the battery.

On the basis of all these calculations you'll determinate the size and number of solar panels you'll need, the number of batteries, power inverter size, etc.

Basic Things to Consider Before Buying a Solar Electric System

Installing a solar power system requires very careful initial planning. First of all, you need to know exactly how much electricity your home uses each month. You may look up in your old electricity bills but also you should think about how your electricity needs will change over the next 10 years.

Solar photovoltaic panels can be installed on the roof, along a wall of the property or as standalone systems. If you are planning to install them on your roof, you need to make sure that the roof is strong enough to hold a solar panel because some of these panels can be quite heavy. A roof inspection (and any necessary repair) is recommended prior to a PV installation. Another thing you need to know is that the more sunlight modules collect, the more electricity they produce, thus the more energy your home will receive. Make sure that the roof (or wherever you intend to install your solar panels) is clear of any obstacles, such as trees or buildings, especially during peak production hours between 10am and 2pm.

Ideally, a solar system will go on a south/southwest-facing roof, although east and west facing roofs are good candidates, as well.

You should decide whether your system will be grid-connected, off-grid or hybrid. With a solar PV system connected to an electric distribution system (grid-connected) you can receive back-up power from it when your system doesn’t produce enough energy for your needs. When your solar PV system produces excess power, that electricity can be send back into the grid, and your local utility is required to buy it from you.

Picture: apps1.eere.energy.gov

A grid-connected solar power system is easily integrated into the existing electrical infrastructure of a house and the system can provide decades of reliable and environmental friendly electricity production.

A stand-alone (off-grid) solar PV system is independent of an electricity distribution grid operated by a utility. The electricity is provided by solar power alone and stored in a battery for later use. Such systems typically make sense in remote locations.

The average solar PV panel last approximately 30 years and many manufacturer warranties last for up to 20-25 years. Solar PV panels are designed and installed to be low-maintenance. However, it is very important to have your solar panels cleaned regularly because they benefit from being hosed off with water twice a year, especially after long periods without rain. Dust or dirt may cause a 10-15% reduction in their efficiency.

Before buying and installing the panels it is also essential to make sure that you understand the installation regulations in your local area. In most cases it is wise to check with the local authority before installing your solar electric system.

Lemonade Award

I was nominated with an award - the Lemonade Award and this is my first award as a blogger (well, this is also my first blog). So, I would like to thank Eco Mama, Its all about our home, the Earth! and Goal For The Green for awarding me with it, and assure you that I really appreciate this acknowledgement! I think that making lemonade out of lemons can be an interesting endeavor, and besides, I like both lemons and lemonade :)

The Lemonade Award is passed to bloggers for showing great Attitude and/or Gratitude and now it's my turn to pass it to ten other blogs.

And here are my nominations :

SolReka
Environmental Chaos
Passionate Green
Chasing The Wind
Green not Mean
Eco-Blogical
Bulgarian Slivatree
Newton's Ocean
Life on a Southern Farm
Teddy Tour

The rules of this award for recipients:

1. Put the logo on your blog or post.

2. Nominate at least 10 blogs which show great Attitude and/or Gratitude!

3. Be sure to link to your nominees within your post

4. Let them know that they have received this award by commenting on their blog.

5. Share the love and link to this post and to the person from whom you received your award.

Solar Energy and Solar Power

Solar energy and solar power are two terms that are often used interchangeably but actually they are not the same thing. They both mean to receive and use solar rays, but more specifically solar power refers to electricity generated from the sun's light.

Solar energy is a more generic term and it describes all the uses of the light and heat from the sun. That includes solar power generation, but also solar thermal for water heating, space heating and cooling, and heat for industrial processes. Solar energy includes also passive solar energy that uses building orientation, design and materials to heat and cool buildings. 

Solar power is generated directly using photovoltaic (PV) technology. Solar PV panels (made from a semiconductor material) harness sunlight to create electricity to run appliances and lighting in your home. The electricity created by the solar system is direct current (DC), and the electricity we use in our homes is alternating currents (AC). Thus solar systems need an inverter which changes the DC current into useable AC current.

There are also concentrating solar power systems. They concentrate the sunlight using mirrors or lenses onto a receiver to produce heat. Then the heat can be used to generate electricity through steam turbines.

Solar energy is clean, environment-friendly, and most abundant renewable energy source we can use. In my next few posts, I will write about producing your own solar electricity by installing solar PV panels on the rooftop of your house, and what basic information householders need to know at the beginning.

Solar Heating Panels on the White House Roof

Still under the impression of the USA 2008 Presidential vote (although I am not an American) I found this information interesting to be published now.

Did you know that way back in 1979 (during the second US oil crisis) the American President Jimmy Carter installed solar heating panels on the roof of the White House West Wing? I personally didn't know that curious fact! And it seems that the Nobel Prize winning President Carter was quite a visionary.

In July 1979, President Carter outlined his plan for achieving energy independence and improving energy efficiency in his "Crisis of Confidence" speech. In an effort to set an example for the nation, he installed solar panels on the White House roof. They were more as a symbol of a new strategy to reduce America’s dependence of foreign sources of energy and a move designed to support Carter’s solar institute, which he had “created to spearhead solar innovation.”

Carter called for 20 percent of American energy to come from solar power by the year 2000. He even had very generous tax reductions implemented for people who installed solar panels at home.

The solar-energy system that President Carter installed consisted of 34 solar collectors which were used to heat water for the staff eating area and some other areas of the White House.

At the time, President Carter warned "a generation from now, this solar heater can either be a curiosity, a museum piece, an example of a road not taken, or it can be a small part of one of the greatest and most exciting adventures ever undertaken by the American people; harnessing the power of the Sun to enrich our lives as we move away from our crippling dependence on foreign oil." (It turns out Carter's warning was at least partially correct: One of his solar panels is now museum piece.)

In 1986, President Reagan had the solar panels removed during a roof in repair and put them into a federal storage facility. Actually, the solar panels were supposed to be reinstalled but they never were.

In 1991, the environmentally-minded Unity College of Maine, found the panels in a government warehouse in Franconia, Va., bought them for peanuts and installed them to use for the generation of hot water in the student dining hall.

By 2004, the solar panels had worn out. Unity College kept one of the panels for “historical significance,” donated another panel to the Smithsonian Institute and offered the rest for sale.

Even a documentary film has been made about the solar panels, using them as a backdrop to explore American oil dependency and the political lack of will to pursue alternative energy. Swiss directors Christina Hemaner and Roman Keller follow the route of the panels in the hour-long film "A Road Not Taken."

In 2003, the National Park Service, which manages the White House complex, installed a nine kilowatt solar electric or photovoltaic panels, on the roof of the main building used for White House grounds maintenance. Solar thermal systems were also installed to heat water: one for landscape maintenance personnel, the other for the presidential pool and spa.

Cellular Base Stations Powered by the Sun

It seems that the mobile industry is another technology field where solar power soon can play an important role in reducing costs and ensuring a reliable power supply.

In a new study ABI Research analysts predict that the future mobile phone base stations will be sun powered. They say that over 335,000 base stations worldwide will be using solar power by the end of 2013, with around 40,000 of those being completely autonomous and off-grid. The research firm explained that improvements in photovoltaic cells have meant that solar energy is now a viable option for supplying power to charging stations.

"The market for autonomous solar powered cell sites looks set to grow from extremely modest levels today to over 40,000 renewable energy sites by the end of 2013. A further 295,000 base stations are expected to supplement on-grid power usage with solar," said Stuart Carlaw, vice-president of ABI Research.

Still, the majority of these cellular base stations will use diesel or mains electricity to supplement their solar panels, especially in areas where population density and less solar energy require it.

Probably the developing countries will be the biggest winners as remote communities will receive phone coverage and Internet connections for the first time. According to some UN figures half of the world is still not able to make a phone call.

Other alternatives to normal electricity for base stations being considered are wind power, fuel cells and even compressed air.

Source: Market Watch

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.

Silicon-Based Solar Cells for Flexible and Transparent Solar Applications

Scientists at the University of Illinois at Urbana-Champaign have developed new high-efficient silicon-based solar cells that are flexible enough to be incorporated on a curved surface or fabric, and transparent enough to be used to tint windows on buildings or cars.

The finding, reported in the journal Nature Materials, offers a new way to process conventional silicon by slicing the brittle wafers into ultra-thin layers and carefully transfers them onto a flexible surface.

"We can make it thin enough that we can put it on plastic to make a rollable system. You can make it gray in the form of a film that could be added to architectural glass. It opens up spaces on the fronts of buildings as opportunities for solar energy.” said John Rogers of the University of Illinois at Urbana-Champaign, who led the research.

Many international companies are making thin-film solar cells, but they are usually less efficient at converting solar energy into electricity than conventional cells.

Rogers' team uses a special etching method to slice very thin solar chips off the surface of single crystal silicon wafers which are highly efficient but, in their current form, rigid and fragile. The sliced chips are 10 to 100 times thinner than a normal silicon wafer, and the size can be adapted to the application. Once sliced, the bits of silicon chips are picked up by a special device and deposited on the target surface "like a rubber stamp".

“These silicon solar cells become like a solid ink pad for that rubber stamp. The surface of the wafers after we’ve done this slicing become almost like an inking pad,” said Rogers. “We just print them down onto a target surface." "The final step is to electrically connect these cells to get power out of them," he said.

Adding flexibility to the material would make the cells far easier to transport. Rogers envisions the material being “rolled up like a carpet and thrown on the truck.”

The technology has been licensed to a startup company called Semprius in Durham, North Carolina.

Sources: Reuters & Energy Efficiency News

Solar Fashion: Solar-Powered Purse for Ladies

Since I'm interested in solar energy and all information related to it, I was curious to find out if there are any cool solar-powered gadgets/accessories available out there that would be of interest for the ladies. So, after doing a little research on the net I came across Solarjo's Power Purse - a fashionable-looking solar-powered purse.

Actually, this is a black rectangular handbag (6" x 12" x 3"), the brainchild of Joe Hynek, a PhD student of mechanical engineering, who designed the bag in 2005, during a handbag competition in an experimental garment design class at Iowa State University. The initial inspiration for incorporating solar cells into clothing and accessories, Joe Hynek got when he worked at a solar panel manufacturer in Ames, making solar panels that work with military applications.

This very creative, eco-conscious high-tech handbag is covered with laminated solar panels made of thin-film photovoltaic cells, which absorb the sun’s rays and create electricity. The purse design incorporates six solar panels outside and two batteries tucked away inside its lining connected to a USB port, so that you can charge your small electronic gadgets that you carry around with you. Electronic gadgets such as cell phones, ipods, Blackberrys, etc. can be attached directly to the USB port, or by using an adaptor.

The stylish purse needs to be exposed to 2 hours of sunlight in order to fully charge a mobile phone battery. The purse’s fully charged battery can last for up to a month.

The Power Purse's current price is about $300 (£150) and it is likely to be available for purchase by the end of 2008.

Joes Hynek's website: Solarjo.com

Sources: Daily Mail & Environment News Service

Solar Hot Water Systems in Israel

Solar Hot Water Heaters in Israel
Photo credit: www.flickr.com/photos/juliepics

I continue my series on solar water heaters with the interesting information that more than 90% of Israeli households have solar water heating systems. Today, Israel is the world’s largest per capita user of solar water heaters. Actually, solar hot water systems are so popular in Israel because by law, all houses constructed in Israel must have them installed.

These heaters were first installed during the 1950's when Israel experienced a fuel supply shortage and severely restrictions were placed on the times when people could heat their water. As a result, many Israelis started to purchase and install solar water heaters on the rooftops of their homes.

In 1983, about 60% of the population heated their water with the sun. Eventually, a law was passed making solar heating mandatory for new residential buildings. The law has saved Israel and its citizens millions of shekels in energy costs. And each year it is also saving between 2% and 3% of the country's electricity needs.

Over the years, the solar hot water systems improved and mass production lowered the cost, so that more companies entered the field. Today purchasing and installing (usually by the builders) a solar water heating system is common practice.

The country’s leader in solar water heating sector is Chromagen with a range of thermo-tanks from 30 to 300 liters capacity linked to solar collector panels. The company produces small and large systems for domestic and industrial purposes. The systems are suitable for households, hotels, hospitals, senior citizens homes, swimming pools and other commercial uses.

Solar Water Heaters Types

Active indirect solar water heating system
Image credit: www.southface.org

Solar water heaters are also known as solar domestic hot water systems or residential solar water heaters. There are different types of solar water heaters and the choice depends on the temperature required and the climate.

Basically, solar water heaters can be either active or passive. Active systems use electric pumps, controls, and other such equipment to circulate water or heat-transfer fluids through the collectors. They also require electric power to activate pumps and/or controls.

Passive solar water heating systems require no moving parts and rely on thermodynamics rather than electric power to circulate the household water or a heat-transfer fluid through the system. Passive solar water heaters are the simplest solar water heating systems and they are also called bread box or batch heaters. These systems are most common in regions that do not experience extensive periods of below freezing temperatures.

Active solar water heaters can be further characterized as direct (open loop) or indirect (closed loop) systems. These terms explain the way the water is heated. With direct heating system household water from the storage tank is circulated through the solar collector, heated by the sun and returned to the storage tank. Direct active systems use pumps to circulate household water through the collectors. Direct solar thermal systems work best in warmer climates where the system is less prone to freezing.

Indirect systems use a heat-transfer fluid (usually a glycol-water antifreeze mixture) to collect heat and a heat exchanger to transfer the heat to household water. Indirect active systems also use pumps to circulate heat-transfer fluid through the collectors. Heat exchangers transfer the heat from the fluid to the household water stored in the tanks. Indirect systems are popular in areas subject to extended freezing temperatures because they offer good freeze protection.

Direct systems are more efficient that indirect ones but they require more maintenance to keep the pipes clear of mineral deposits.

China's Solar-Powered City Rizhao

Since I found this information interesting and inspiring I decided to publish one more post about China and solar energy, this time featuring China's solar-powered city Rizhao. China has a major problem with pollution, largely as a result of the country's rapid industrial growth and a large increase in energy consumption, which is primarily provided by coal power plants. So, I think that projects and strategies like this one in Rizhao deserve admiration and popularization.

Rizhao is a "small" coastal Chinese city of nearly three million, located at the southern end of Shandong Peninsula and bordering on the Yellow Sea. It is a rising seaport and tourist city, with golden beaches, mild climate and lots of sunshine - Rizhao receives an average of 270 days of sunlight every year. Recently, Rizhao has gained much popularity because of using sun's light and heat to provide energy, thus limiting the city’s carbon emissions and urban pollution. By using the simple, cheap solar devices that sit on the almost all of Rizhao's rooftops, the city has cut its yearly carbon dioxide emissions by about 53,000 tons. The features of a coastal city with “large green space, gardenable, open and ecological” are also obvious. The public green space per capita is up to 16 m3.

In Rizhao City, which means "City of Sunshine" in Chinese, an incredible 99% of households in the central districts and more than 30% do so in the outlying villages use solar water heaters. Also, six thousand houses have solar cooking facilities and 60,000 greenhouses are heated by solar panels, reducing overhead costs for farmers in nearby areas. Almost all traffic lights, street lamps and park illuminations are powered by photovoltaic solar cells. In total, the city has over a half-million square meters of solar water heating panels, the equivalent of about 0.5 megawatts of electric water heaters.

Rizhao Municipality has made great efforts to build Rizhao into a modern coastal Ecocity. Mayor Li Zhaoqian explained: "It is not realistic to subsidize end users as we don't have sufficient financial capacity." Instead, the provincial government heavily invested in the local solar panel industries to achieve technological breakthroughs, which increased efficiency and lowered the unit cost.

Since 2001, Rizhao City officials have been educating people and implementing building regulations to promote the use of solar panels. A combination of investment in the industry, regulations and public education spurred the broad adoption of solar heaters. The city mandates all new buildings to incorporate solar panels, and it oversees the construction process to ensure proper installation. To raise awareness, the city also ran public advertising on television and held open seminars.

Rizhao has been granted many honorable titles, such as National Model City of Environmental Protection, China’s Outstanding Tourism City, Environmentally-friendly National Model City, and National Garden City.

Sources: Renewable Energy World, Worldwatch Institute

China - a World Leader in the Solar Water Heating Market

A roof-mounted solar water heater
Photo credit: www.bcsea.org

China is by far the world's largest producer and consumer of solar water heaters. A basic models of solar water heaters in China are very cheap, starting at around 1,500 yuan (US$190). By 2006, the cumulative installed area of water heating collectors in China hit 100 million square meters, and that is roughly 80 percent of the global solar thermal capacity installed worldwide. But this number corresponds only to 78 sqm of collector surface installed for every 1000 inhabitants, which implies a large margin of market potential. So, although China is the biggest solar thermal producer and market in the world, per capita installations of solar hot water systems are still quite low compared to countries like Israel, Greece, Cyprus, Germany and many others.

More than 30 million Chinese households now have one solar water heater installed, and the popularity is due to the efficient evacuated tubes which allow the heaters to function even under cloudy or smog-choked skies and at temperatures well below freezing. The evacuated tube technology was initially developed by Qing Hua University in Beijing in the early eighties, with pilot manufacturing in 1985.

A report from the China's top planning authority predicted that by 2010, the coverage of solar water heating systems in operation in China will reach 150 million square meters. It is also estimated, that by utilizing solar energy, China can save more than 50 million tons of coal in 2010.

"Green Olympics" - Beijing 2008

Beijing National Stadium - 'Bird's Nest'
Photo credit: Guo Lei/Xinhua

The 2008 Summer Olympics in China are in their apogee and they are drawing a lot of attention. Taking into account a massive global audience, the Beijing Olympic organizers are hoping to focus our attention to climate changes and popularize the idea of using eco-friendly technologies. The "Green Olympics" may help change peoples attitudes and set standards for future building projects in China and around the world.

The Olympic organizers are trying to make the Olympic Games environmentally friendly and Beijing a model city for using green technologies, zero net emissions and sustainable architecture. As a part of these efforts, more than a quarter of the energy used at Olympic venues is coming from renewable sources.

Beijing's Olympic Village is a great example of sustainable community development. All seven main Olympic stadiums are equipped with solar generators capable of outputting 480 kilowatts of energy at any given moment. The entire hot-water supply for the Olympic Village will be powered by solar energy. Photovoltaic panels are incorporated on the stadium walls and roofs for most of the outdoor lighting. Also, the main stadiums will receive power from Beijing's first wind farm.

Beijing National Stadium - 'Bird's Nest' includes a rainwater collection arrangement, a natural ventilation system and its upper surface is clad with Ethylene Tetrafluoroethylene (ETFE) roof panels, that let in natural light. The stadium is referred to as the ‘Bird’s Nest’ because of its saddle-shaped steel roof and interwoven façade

The spectacular-looking structure called "Water Cube" looks like a building made of bubble-wrap. It is officially known as the National Aquatics Center and is completely surrounded with ETFE pillows. It is expected to cut energy use by 30 percent and has been built so that after the Olympic Games to be converted easily to a shopping area and leisure center.

The idea for the Beijing's "Green Olympics" makes perfect sense because China sees its energy costs rising and energy sources dwindling, as well as significant damage to the environment. And the so-called "Green Olympics", although will not solve China's environmental issues, they could point the way to a more sustainable future, according to officials and experts.

China is already a world leader in many renewable energy technologies, but so far many of the green technologies have been for export only, because they are too expensive for the country to use itself. China, for example, led the world in manufacturing and utilisation of solar water heaters and energy efficient light bulbs. It is also on the way to becoming the world leader in wind turbine manufacturing and installation.

Going Green with a Solar Water Heater

Utilizing energy of the sun to heat water is one of the oldest forms of solar technology available. The first commercial solar hot water heater was patented by Baltimore inventor Clarence Kemp in 1891 (he called his solar water heater the Climax), and since then improvements in performance, design, and level of complexity have made solar water heaters the perfect choice for homeowners looking to go green and create more sustainable home.

There are several different types solar water heaters, including those with pumps and those that work passively. Basically, solar water heating systems have two main parts: a hot water storage tank and some type of collector that absorbs solar energy. The most modern solar water heaters mount flush with a home's roof and resemble skylights. Geographic location, collector orientation, and collector size will determine how much energy can be provided for domestic hot water heating.

On an average single-family residence, there will typically be one or two solar collector panels on the roof. Some homeowners use the solar water heating system exclusively (sometimes with a gas or electric tankless water heater as a backup energy source), while others pair them with other systems as pre-heaters.

Solar water heating systems cost depends on a number of factors, such as the size of the system and the particular system manufacturer, the number of people in the household, the current hot water usage, the type of roof it is going to sit on, trees causing shadows, etc. The typical solar heating system costs in the range of $2,000 - $6,000. Any solar rebates and other incentives available in your area will reduce the total cost. You can find more detailed information about it at www.dsireusa.org (for USA customers).

Using solar energy to meet part or all of your home's domestic hot water needs have a good economic payoff and can be a valuable and cost effective option to invest. When correctly installed, a solar hot water system can reduce your water-heating bills 50-80%, depending upon water consumption. With a solar water heating system, you'll get the hot water your household needs, save electricity which means saving money, reduce your dependence on coal-fired power and benefit the environment. Saving electricity means reducing emissions created by burning fossil fuels and water consumption at power stations, thus taking steps to save the environment. When a water heating system is combined with an electric water heater, pollutant emissions are reduced by about 2,800 pounds per year. A solar system replacing natural gas will reduce pollution by 1,200 to 1,600 pounds annually.

Solar water heaters pay for themselves in four to eight years and should function for 20+ years.

Solar Energy from Saharan Sun Could Power Europe

Solar thermal parabolic trough power plant;Source: Solar Millennium, TREC

According to an article published recently in the UK’s Guardian newspaper, EU scientists are working on an ambitious plan to harvest the sun in the Sahara desert in Africa to provide electricity for Europe. Europe needs a lot of electricity, but gets little sun. Vast solar power farms in the Sahara desert could provide clean electricity for the whole of Europe.

The EU scientists are calling for the creation of a series of huge solar farms - producing electricity either through photovoltaic cells, or by concentrating the sun's heat to boil water and drive turbines - as part of a plan to share Europe's renewable energy resources across the continent.

Speaking at the Euroscience Open Forum in Barcelona (ESOF), Arnulf Jaeger-Waldau of the European commission's Institute for Energy, explained how electricity produced in solar farms in Africa, each generating around 50-200 megawatts of power, could be fed thousands of miles to European countries by using high-voltage direct current (DC) transmission lines instead of the conventional alternating current (AC) lines. Energy losses on DC lines are far lower than AC ones where transmission of energy over long distances is uneconomic.

Depending on the size of the grid, building the necessary high-voltage lines across Europe could cost up to €1-billion a year every year till 2050, but Jaeger-Walden pointed out that the figure was small when compared to a recent prediction by the International Energy Agency that the world needs to invest more than $45-trillion in energy systems over the next 30 years.

Doug Parr, Greenpeace UK's chief scientist, welcomed the proposals: "Assuming it's cost-effective, a large-scale renewable energy grid is just the kind of innovation we need if we're going to beat climate change."

The idea for developing a major innovative super-grid based on renewable energy is already gaining political support in Europe, with both the UK Prime Minster Gordon Brown and and the President of France Nicolas Sarkozy, recently backing the north African solar plan.

The scientists say that harnessing solar energy from the Sahara would be especially effective, because the sunlight in that area is much more intense: solar photovoltaic panels in northern Africa could generate up to three times the electricity compared with similar panels in northern Europe. And it would require the capture of just 0.3%of the light falling on the Sahara and Middle East deserts to meet all of Europe's energy needs.

Source: http://www.guardian.co.uk/environment/2008/jul/22/solarpower.windpower?gusrc=rss&feed=environment

Note: An earlier article in Spiegel Online from April 30, describes the project and also how it will benefit Africa because it is important that such an ambitious development is sustainable and beneficial to both continents. Read more: "Is Desert Solar Power the Solution to Europe's Energy Crisis?"

For the original plan visit: http://www.desertec.org/concept.html

Solar-Powered Umbrella - Unique Light for your Patio or Backyard Area

Solar-powered umbrella is an excellent idea and a really cool summer gadget that already exist on the market and you can buy one for your patio, backyard, or garden.

This item is great for providing shade during the day and lights for your patio or backyard area at night without adding to your energy bill. During the day, it utilizes and stores energy from the sun in a solar panel located on top of the umbrella. When the sun goes down, the solar patio umbrella lights automatically turn on, proving sophisticated, gentle illumination. It is perfect for those outdoor summer gatherings and romantic dinners.

Solar-powered umbrella has a hi-tech solar panel attaches at the finial (top) of the umbrella to power the white LED's which are located on the ribs. Most models have also been designed with a center hub light that includes several LED's inside. The batteries inside the solar panel are replaceable and the LED's are also replaceable. The panel will charge in direct sunlight and fully charged provides 6-8 hours of light.

Solar-powered Tech Chair on the Beach

The solar-powered Tech Chair is definitely an interesting idea thought up by experts from the UK-based computer retailer PC World. It may easily become the summer favorite possession especially for the geeks as it boasts all the essential ports for various gadgets to hook up to while you're lying on the beach and tanning under the summer sun. Keep in mind, however, that you should place all your gadgets in a shaded area or under an umbrella, since the direct exposure to sunlight is incompatible with electronics.

The major feature of the chair is that it is solar-powered, harnessing energy from the sun so you can plug in all your gadgets. The overhead shade maker is equipped with solar cells to power the docks for your phone, MP3 player, camera, video recorder, and laptop, plus there's a game console holder, LCD screen, speakers, and headphone sockets. An interesting feature also is the automatic sunshade which follows the sun to keep your face shielded. The special solar fabric will provide protection from sun, wind, sand, water and suncream.

Perhaps most useful is the built-in long-range WiFi and Bluetooth antenna for keeping you connected. Another nice thing is a sliding laptop table which is available so you can work in the sun. And at the foot of the tech chair there is even a GPS device.

Anina Castle, spokesperson for PC World said: "We're also looking to incorporate a mobile text reservations system, whereby the Tech Chair can be booked by text and located via GPS so Britons don't have to worry about getting up before their early-rising European cousins."

"The Tech Chair unites a number of electrical products in a lightweight portable package that can be folded into a compact suitcase design small enough to take as carry-on luggage.", a PC World spokeswoman also said.

The solar-powered Tech Chair is still a concept design and experts have not yet worked out how much it will cost to buy.

Sources: The Design Blog, Sky News, Metro Headlines

Rotating Skyscraper Powered by Wind and Sun in Dubai

The Italian architect David Fisher said he is ready to start construction on a  futuristic rotating skyscraper in Dubai that will be "the world's first building in motion". The modern "Dynamic Tower" construction, which would be energy self sufficient and cost about 700 million dollars to build, will represent an 80-storey tower with revolving floors that give it an ever-shifting shape. 

The spinning floors, hung like rings around an immobile central column, would offer residents a constantly changing view of the city's skyline and the Persian Gulf. Each floor will rotate independently at different speeds. It will take between one and three hours for the floors to make a complete rotation.

Rotating floors are just one of several futuristic features in the building. Using wind and solar power, it will generate more electricity than it uses. Horizontally mounted giant wind turbines fitted between each rotating floor will generate enough energy to power the tower and nearby buildings. 20% of each roof will be exposed to the sun and photovoltaic cells placed on the roof of each rotating floor will produce solar energy. For the interior of the luxury apartments will be used only natural and recyclable materials, including stone, marble, glass and wood.

The dwellings will be assembled in a factory outside Bari in southern Italy, equipped with plumbing and electricity systems, kitchens, bathrooms and ceilings. They will arrive also painted, decorated and, in some cases, with walls hung with artwork. An apartment will cost between $3.7 million to $36 million dollars. Lifts will allow penthouse residents to park their cars right at their apartments.

The plan was revealed by Mr Fisher in a press conference at the Plaza Hotel in New York on June 24. "Today's life is dynamic, so the space we are living in should be dynamic as well," he said. "Buildings will follow rhythms of nature. They will change direction and shape from spring to summer, from sunrise to sunset, and adjust themselves to the weather. In other words, buildings will be alive."

Construction of the rotating skyscraper is scheduled to be completed by 2010.

Update 2020: The project has not been completed yet.

Mandatory solar panels in German town of Marburg

The central German town of Marburg is the first in German to make solar panels mandatory for almost all rooftops of private and commercial buildings. The controversial new law requires a solar panel for every new building and every old building that is being renovated. The historical buildings such as the Marburg Castle, Marburg's City Hall, and the Elisabeth Church will be exempt from the requirement.

The solar law was approved by the town's council on June 20, and will take effect Oct. 1. According to the law, a 1 square meter (10 square feet) panel must be installed for every 20 square meters (200 square feet) of surface area. Installing the panels could cost homeowners up to €5,000 ($7,800). The cost would be paid off through savings in energy bills over a 15-year period, the town's mayor, Franz Kahle, said. Those violating the law will face fines starting at €1,000 ($1,500).

The town is home to Marburg University and has about 80,000 residents. Most of the residents support the decision made by the Social Democrats and Greens, but the opposition leaders say that to force people to equip their homes with solar panels equates to a "green dictatorship," and that "nobody dares to say anything."

"Sometimes you must force the hand of consumers for their own good", says the specialist in solar Vajen Klaus, a professor at the University of Kasel.

Solar Photovoltaic (PV) Panels

Solar photovoltaic (PV) technology uses the sunlight to produce electricity. PV cell is the smallest element in the PV system. A PV cell is made up of two thin layers of semi-conducting material (usually silicon), treated with small amounts of substances giving the cell the means to produce electricity when exposed to sunlight.

The basic PV or solar cell typically produces only a small amount of power. To produce more power, solar cells can be connected in series to make a PV module (a.k.a. PV panel, solar electric panel). Solar cells or more photovoltaic modules form a PV array. The amount of power solar panels produce is determined by the quality of the solar panel, solar cells and technology used in making the solar panel.

Conventional PV solar panels made from silicon wafers (monocrystalline silicon) convert about 17 to 20 percent of sunlight into usable electricity. The latest solar panels that utilize the new cell can convert into electricity 22 percent of the sunlight they collect. Polycrystalline panels efficiency typically range from 15% to 17%.

Typically, PV panels are mounted on a roof or are integrated in the roof so they act as both a part of the roof or shingles, and a solar panel at the same time. PV can also be incorporated as building facades and canopies. Integrated PV systems are usually installed during construction of the building. The amount of power that a PV panel will deliver is proportional to the amount of sunlight that falls upon it. Ideally PV panels are best placed so that they face south (±450). Photovoltaic panels, however, suffer from decreased power output when they heat up, so high temperatures decrease their efficiency.

When the PV panel is tied to a power grid, the DC (direct current) is converted to alternating current (AC) at grid rating by an inverter. Grid connect PV systems are often integrated into buildings. If you generate more power than you consume, the meter spins backward, as that surplus electricity flows back into the grid for others to use. By returning surplus electricity to the grid, no battery is needed. Some power companies will compensate surplus at a rate that is different than the cost of consumption.

A basic off-grid PV system consists of a solar panel, which generates DC power, a battery bank that stores the DC power, and an inverter (if AC power is required). Modern PV systems are also equipped with some kind of electronic charge controller. The main job of the charge controller is to prevent the battery from being overcharged and also from deep discharging of the battery. The charge controller also protects the solar panels from electrical damage.

The working life of a solar panel is approximately 20 to 25 years and once purchased they continue to produce electrical power for many years. Virtually, they require little or no maintenance, but dust or grime on the front of solar panels will substantially reduce the output, so they should be cleaned periodically.

Applications of Photovoltaic PV Power Today

PV power, definitely, is not just the energy of the future. Thousands of PV systems are used in the world today for a variety of applications because they can be easily adapted to suit any requirement - large or small. Virtually any power need can be met with photovoltaics, although some are more cost - effective than others.

PV cells have been used for many years in our daily lives to power small applications such as watches and pocket calculators. Today there are available numerous small, medium and large-scale PV applications for residential and industrial purposes. This includes PV power plants, stand-alone PV arrays, building-integrated PV systems, PV solar lighting applications, PV water pumps, solar powered cell phone chargers, and other solar accessories for our homes and businesses. In general, though, PV is not used to generate electricity for space heating, hot water, electric cook stoves or ovens, or other applications with high power needs.

Lighting is one common use for PV systems. Cost-effective applications of lighting powered by photovoltaics include garden lights, lighting for recreational areas, street lights, etc. Remote monitoring, telecommunications equipment, highway construction signs, and navigational warning signals are also excellent applications for PV.

PV systems are an economical option for remote residences and rural areas. In most remote places, it is impossible to connect to the electrical grid and in many such locations, photovoltaic technology is the least-cost option for meeting remote energy needs.

PV systems are used effectively worldwide to pump water for plants, livestock, or humans. Since the need for water is greatest on hot sunny days, PV is a perfect fit for pumping applications. Water can be pumped into a storage tank during daylight hours, then distributed by gravity whenever it is needed. In the developing world, entire village water supplies are powered by photovoltaics.

PV systems offer a number of unique benefits that have led to their rapid growth in popularity in recent years. This growth was particularly impressive in countries such as Japan, Germany and the US.

Dream Big: Solar Future

Solar energy has captured the human imagination and the news like the previous one about building solar-powered speedboat shows that high quality solar technology exists here and now. The story sounds somewhat distant from the everyday life of the average person since only a few very rich people can afford such a pricey water vehicle. However, I think that all news concerning solar energy are important and they worth to be published not just out of curiosity. Solar-powered aircrafts, solar-powered boats, solar-powered cars, or solar-powered houses - maybe all this still sounds unrealistic, or utopic, or futuristic for many people. But I believe that one day (not so far in the future!), it could be an real and affordable option for all of us. Or at least... we can dream!

First Solar-Powered Speedboat

The world’s first solar-powered speedboat Czeers Credit: Czeers

Recently was announced that two Dutch researchers at the Technical University of Delft - Nils Beers and David Czap managed to develop the world's first solar-powered speedboat Czeers MK1. (a combination of their last names makes Czeers, pronounced "Cheers").

The speedboat was made from 100% black carbon fiber and covered with 150 square feet (14 square meters) of solar cells. The solar vehicle can approximately reach a top speed of 30 knots (about 35 miles / hour or 55.5 km/ph). The solar powered motor allows the boat to operate quite gentle.

The whole décor is luxurious: the boat has a LCD touch-screen control system and a fine leather interior. The approximate price is seven hundred thousand euro, or about $1.1 million.

Sources: FoxNews & Uberreview

The Flight of Solar-Powered Aircraft Helios

Here is a video showing compilation of test flights of the solar-powered, remotely piloted NASA's Helios aircraft.

Helios set out from Kauai in the Hawaiian Islands before 9:00 AM on Monday, August 13, 2001. Just over seven hours later, it reached 96,500 feet. Flying at about 25 miles an hour, the mission lasted nearly 17 hours, landing at 1:43 a.m. August 14, 2001

This was the first time a non-rocket powered aircraft has maintained flight this far above the earth. At this altitude above ground the sky is almost black, stars shine in the daytime, and the horizon looks curved.

Helios was an ultralight flying wing built by AeroVironment Inc, as a part of NASA's Environmental Research Aircraft and Sensor Technology (ERAST) project. Covered with solar cells, Helios' impressive 247 foot wide wing exceeds the wing span and even overall length of a Boeing 747 jet airliner.

Helios had about 62,000 solar cells across the wing. The solar cells collect energy from the Sun and convert it to electricity, which runs the 14 small motors. The motors turn the 14 propellers, which are specially designed to pull the aircraft aloft even in the very thin air that's 18 miles high.

Helios was intended as a technology demonstrator, but in the extremely thin air 100,000 feet above Earth's surface, the flight of Helios also approached conditions for winged flight in the atmosphere of Mars, since the atmosphere at that height above earth replicates the atmosphere near the Martian surface.

More Key Steps in Photovoltaic History

The world’s most advanced solar-powered airplane Icare Credit: University of Stuttgart, Germany

In 1955, the first solar-powered automobile was publicly demonstrated in Chicago. It was a 15-inch Sunmobile built by William G. Cobb of the General Motors Corporation. Light energy falling on 12 selenium photoelectric cells created electric current to power a tiny electric motor. The solar automobile was one of 253 free exhibits of the General Motors Powerama, Chicago, Illinois.

In 1976 NASA’s Lewis Research Center starts the installation of 83 PV power systems on every continent except Australia.

In 1978 was installed the world's first village PV system at Papago Indian Reservation, Schuchuli, Arizona.

In 1980 ARCO Solar is the first company to produce more than 1 MW of PV modules in one year.

In 1981 Paul MacCready builds the first PV-powered aircraft known as the Solar Challenger, which flies from France to England across the English Channel. The aircraft had over 16,000 solar cells mounted on its wings, which produced 3,000 watts of power.

Volkswagen began testing PV arrays mounted on the roofs of vehicles in 1982.

In 1982 a Danish-born Australian eco adventurer Hans Tholstrup drives the first solar-powered car - the Quiet Achiever - almost 2,800 miles between Sydney and Perth in 20 days. The vehicle had photovoltaic system of 1 kW and the average speed was 23 km/h. Tholstrup is the founder of the World Solar Challenge in Australia, considered the world championship of solar car racing.

In 1984, a 1 megawatt photovoltaic electricity plant began to operate in Sacramento, California.

ARCO Solar introduced a G-4000, the first commercial thin film photovoltaic module in 1986.

The world’s most advanced solar-powered airplane, the Icare, flew over Germany in 1996. The wings and tail surfaces of the Icare are covered by 3,000super-efficient solar cells, with a total area of 21 m2.

The 11th tallest skyscraper in New York City, built in the 1990s - the Condé Nast Building, officially 4 Times Square - includes building integrated photovoltaic (BIPV) panels on the 37th through the 43rd floors on the south and west-facing facades to produce a portion of the building’s power.

In 1999 Germany launches a 100,000 solar roofs scheme to promote the on-site generation of clean electricity.

On August 13, 2001 after long research and trial, the solar powered wing aircraft Helios set an unofficial world record by a winged aircraft of flying at a sustained altitude above 96,000 feet (29,250 m) for 40 minutes. Helios is a remotely operated (by two controllers using computers on the ground), solar powered aircraft developed by NASA and AeroVironment Inc.

In 2002 Japan installed 25,000 solar rooftops.

Bringing PV Cells from Space back down to Earth

During the 1960s and early 1970s the use of solar cells in space flourished but down on Earth electricity from the sun seemed not very perspective option. The high costs of the PV cells made them uneconomical for use on the earth where low price is the main factor.

In the early 1970's a way to lower to cost of solar cells was discovered. Dr. Elliot Berman, with financial help from Exxon Corporation, designed a significantly less costly solar cell by using a poorer grade of silicon and packaging the cells with cheaper materials. This brought the price down from $100 per watt to around $20 per watt.

The energy crises of the 1970s led to a worldwide push for alternative renewable sources of energy, and photovoltaic were seen as a possible solution. Major research activities in the field took place and the main objective of photovoltaic research has been to reduce costs in order to bring solar power to people.

Significant efforts were made to develop PV power systems for residential and commercial uses, both for stand-alone, remote power as well as for utility-connected applications. The photovoltaic industry attracted the interest of large energy companies and government agencies. With their investment of capital, tremendous improvements in manufacturing, performance and quality of PV modules were possible.

In the 1980s, photovoltaics became a popular power source for consumer electronic devices. PV cells were incorporated in watches, radios, lanterns and other small battery-charging applications. During the same period, international applications for PV systems to power water pumping, refrigeration, telecommunications, rural health clinics, and off-grid households increased dramatically, and remain a major portion of the present world market for PV products.

Photovoltaics and the Space Industry

The International Space Station in December, 2001. Credit: the crew of STS-108, NASA

Starting in the 1950s and 60s, the space industry was the first market for photovoltaics. Photovoltaics were light and the "fuel" is both weightless and free for the taking. The high costs were never an issue since money was never a problem with the space industry.

In 1954 Bell Laboratories built the first photovoltaic module. It was billed as a solar battery and was mostly just a curiosity as it was too expensive to gain widespread use. Bell Labs used a new process called the Czochralski process to develop the first crystalline silicon photovoltaic cell with an efficiency of about 4 percent. The new technology got the first major commercial push when NASA integrated it into its new space program.

In 1955, the preparation on satellite energy supply by solar cells began. Western Electric put for sale commercial licenses for solar cells production. Hoffman Electronics - Semiconductor Division introduced a commercial photovoltaic product with 2 % efficiency for US$ 25 per cell with 14 mW peak power. The energy cost was US$ 1,785 per W.

In 1957, Hoffman Electronics introduced a solar cell with 8 % efficiency. A year later, in 1958, the same company introduced a solar cell with 9 % efficiency. The first radiation proof silicon solar cell was produced for the purposes of space technology. On 17th March 1958, the first satellite powered by solar cells, Vanguard I, was launched. The system ran continuously for 8 years. Two other satellites, Explorer III and Vanguard II, were launched by Americans, and Sputnik III by Russians.

In 1959, Hoffman Electronics introduced commercially available solar cells with 10 % efficiency. Americans launched the satellites Explorer VI with photovoltaic field of 9,600 cells and Explorer VII.

In 1962, Bell solar cells powered Telstar, the world's first communications satellite.

1964 - NASA launches the first Nimbus spacecraft - a satellite powered by a 470-watt photovoltaic array.

In 1965, the Japanese scientific programme for Japanese satellite launch commenced. The following year, in 1966, NASA launches the first Orbiting Astronomical Observatory, powered by a 1-kilowatt photovoltaic array, to provide astronomical data in the ultraviolet and X-ray wavelengths filtered out by the earth’s atmosphere.

Today, the space industry is still a significant user of photovoltaics since they play an important role in space, providing electrical power to satellites in an orbit around the Earth. Solar cells power virtually all satellites, including those used for communications, defence, and scientific research. More than 600,000 flight-proven solar cells are powering over 60 satellites.

The International Space Station uses multiple solar arrays to power all the equipment on board. The success of the space and planetary exploration missions often depends on their on-board PV power sources — providing power for experiments and for getting the data back to Earth. The three Mars rovers - Pathfinder rover Sojourner, Spirit and Opportunity, completed their missions successfully, powered by PV.

See also: http://www.aerospaceweb.org/question/spacecraft/q0298b.shtml and http://mars.jpl.nasa.gov/MPF/roverpwr/power.html)