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

Solar Morrocan Village - the First Village Powered by the Sun in Africa

Image credit: Cluster Solaire

Thirty-two solar photovoltaic panels were installed to harness the sunlight and power the small village of Id Mjahdi, in Morocco. The village is situated on the sunny Atlantic coast, near the coastal city of Essaouira (around 190km to the west of Marrakesh), and it became the first entirely solar-powered village in Africa.

This news was reported by CNN in December last year but I found this inspiring and decided to write a post about it now. I think that solar energy can help millions of people in Africa to get access to cheap and reliable electricity and to improve their lives in all aspects.

According to the International Energy Agency, solar power may become one of Africa's top energy sources. Of all solar power that is used globally, less than 1% currently comes from the continent Africa. Morocco already has 35 percent of its electricity needs from renewable energy sources (solar, wind, and hydroelectric power), and its goal is to increase the use of renewable energy to 52 percent by 2030, according to the International Renewable Energy Agency (IRENA). "Morocco is unquestionably a leader in sustainable energy," says Francesco La Camera, director-general of IRENA.

Marocco already has the world's largest solar concentrated farm, the Noor-Ouarzazate complex. The solar farm is built on an area of more than 3,000 hectares. The size of the farm corresponds to 3,500 football fields and produces enough electricity to power a city such as Prague, or twice the size of Marrakesh.

And now, Id Mjahdi was chosen for this pilot solar project to demonstrate how remote villages, which are expensive to connect to the power grid of the National Office for Electricity, could be powered with solar energy. The author of this project is Moroccan solar power company Cleanergy. Their idea was to electrify remote communities, and Id Mjahdi was chosen because they needed everything, according to the company's founder, Mohamed Lasry.

The people in Id Mjahdi relied on candles for light, and they usually used them only around an hour for working or studying in the evenings. They used tree bark for heating and cooking, and Id Mjahdi did not even have a nearby source of water. The girls often missed school days to walk several miles to a well. It’s hard to believe that in the 21st century still have such places.

The first step of the project was to build a water tower for the community. The next step was to install 32 solar photovoltaic panels, which generate 8.32 kilowatts of electricity for distribution via a mini-grid. Around 20 homes in the village are connected to the solar mini-grid, serving more than 50 people. Each family was given a water heater, fridge, television, and oven. Each house was provided with an outlet to charge electric appliances. The solar network has also a battery, to store electricity for later use at night. The street lights in the village are also solar. 

The solar project was supported financially by the Moroccan ministry of energy, Moroccan Agency for Sustainable Energy (MASEN), Essaouira’s local authorities, Moroccan non-profit group Cluster Solaire, the French supermarket chain Intermarché, and the soaps company Le Petit Olivier. The cost of the entire project was $188,000.

In October 2019, Cleanergy opened several solar-powered buildings - a hammam (public baths), a workshop providing jobs for women to produce argan oil, and an educational center for children between the ages of three to six, which gives the opportunity their mothers to work. The chance to have a job is another major benefit for the community. 

The educational center comprises two classrooms, a sports field, and a playground. For adults are offered also, basic literacy classes. 

At the village was created an association like a cooperative, and it owns the whole production. The association takes a small fee from the argan oil sales to maintain the solar network. Cleanergy trained the men and women in the village how to manage it.

Now Cluster Solaire is seeking funding to build more solar villages. There are 800 villages without electricity in Morocco alone, and the World Bank estimates that 840 million people lack access to electricity worldwide. 

Id Mjahdi could be a model for other remote community which still lack access to electricity. Around 650 million people will lack access to electricity in 2030, according to the World Bank. It says that mini-grids could be the most cost-effective solution for remote areas, and have the potential to provide electricity to as many as 500 million people by 2030. With about $220 billion of investment, it is possible to build around 210,000 mini-grids. And they also help to save our planet: 210,000 solar mini-grids would help avoid 1.5 billion tons of CO2 emissions globally.

Sources: CNN.com & Internet

Foldable Solar Roof For Parking Lots

A foldable solar roof for parking lots is something new in solar technologies.

Today, solar energy is used all over the world. There are many improvements in already existing solar technologies. Entirely new technologies and innovative solar devices are emerging. More and more people have solar-powered homes. Back in 1956, the cost of solar used to cost around $300 per watt. Now, in the US, you can get rooftop solar for $1.49/watt from Tesla and a similar price from others.

According to the latest news, a company in Switzerland and its partner, Kronberg and St. Gallish-Appenzellische Kraftwerke (SAK), have created something unique in the field of the solar technologies - a foldable solar roof, that comes out only when the sun is shining. It is not a typical roof designed for residential use. This solar roof is meant for parking lots and generates power for on-site consumption, including for electric vehicles charging (there are two charging stations). It also provides shadow to keep vehicles cooled when the weather is hot.
         

                            Image credit: cleantechnica.com

The companies started this project back in the spring of 2020 when they built the foldable photovoltaic system on the Kronbergbahn’s parking lot. When the sun rises, the solar roof unfolds and soaks up the rays to generate solar power, then when it’s cloudy, raining, or during night time, it folds up. The foldable photovoltaic roof is named Horizon, its size is 43,056 ft2 (4,000 square meters), has a 420 kW generation capacity, and it covers the parking lot for 152 cars. The cost of the entire project is about 1.5 million Swiss francs.   

The foldable solar roof  was manufactured at DHP Technology headquarters in Zizers. It uses mono and polycrystalline solar cells and glass-free laminate tech. “The folding sunroof is lightweight because we use glass-free solar module technology,” said the DHP representative. “The installation is simple and is based on the plug-and-play approach.”

The parking lot has 1,320 solar panels and produces 350,000 kWh per year. Right now, the companies are looking for investors who are interested in sponsoring a system. There are 660 panels available and expected to be licensed soon to interested clients. The license agreement is for 15 years. 330 panels are already used by SAK and Kronbergbahn AG.

Investors will receive five different experience vouchers during their 15-year right of use - the vouchers vary depending on the investment. If you are interested in investing in a panel, you have two options. You can invest in a whole panel or by the quarter:

1. Entire Panel CHF 800 ($852)
2. Quarter Panel CHF 200 ($213)

The sources of this news are cleantechnica.com (you can see a video on their website), pv-magazine.com, and interestingengineering.com. 

Solar-Powered Backpack

A solar-powered backpack is one of the recent environment-friendly solar innovations which become more and more popular. It allows the hiker or traveler the opportunity to keep their electronic devices charged anywhere they go using solar energy. 

We live at the age when we are constantly connected to one device or another such as smartphones, MP3 players, tablets, laptops, so the importance of having a source of power with us has never been greater. Here comes a solar-powered backpack. It can harness enough solar energy to keep us connected with the world and it is ideal for people who like to take hiking trips or go camping.

The solar-powered backpack has a small solar panel attached to its outer surface so we can capture the sun’s rays. The interior space includes a storage battery and other components. The solar panel is lightweight, waterproof and can produce up to 10 watts of power. 

Other components of the solar-powered backpack include a flexible mono-crystalline or thin-film solar panels, charge controller, a variety of cell phone adapters and a USB plug for your MP3 player.

With the solar-powered backpack, you can also power a GPS, a travel lamp, a digital camera, a palm pilot, and other rechargeable electronic devices.

The solar-powered backpack has a lithium-ion battery pack inside to store this energy. NASA and the US Army have used copper indium gallium diselenide (CIGS) solar cells for its unbreakable strength and flexibility.

A solar-powered backpack known as REPPS (Rucksack Enhanced Portable Power System), was first used by the US army for communication equipment in 2010 in Afghanistan. The US Air Force had previously used solar panels on shipping containers, developed by Lockheed Martin. And the Marines developed suitcase units of foldable solar panels which can also be carried as a backpack.

A solar-powered backpack can also be used for international aid, disaster relief, and humanitarian relief efforts where power from the utility grid is not available. (read this article)

Several companies are manufacturing solar backpacks and they range in price from $75 to $500.

How to Harvest Solar Energy on Cloudy Days

Image credit: SunModo

Talking about solar energy without sunlight, it is interesting to see how solar energy can be harvest on cloudy days. 

Even on cloudy days, there’s still solar energy send down to earth from the sun. And although solar panels don’t produce as much electricity as they do on sunny days, they have been shown to produce 25% of what they produce on a sunny day, or 10% when it’s very cloudy. The exact amount will vary depending on the density of the clouds, and may also vary by the type of solar panel - some kinds of panels are better at receiving diffuse light. SunPower solar cells, for example, have been designed to capture a broader range of the solar spectrum. By capturing more red and blue wavelengths, their solar panels can generate more electricity even when it’s overcast.

We may assume that solar panels thrive in hot, sunny weather, but too much heat can also reduce solar panel output 10-15%. The very hot climate isn't the best condition for them. Most solar panels' power outputs start to degrade if the temperature of the panel goes over about 25°C. 

Solar power can work well in areas known for cloudy, cold weather. For example, New York, San Francisco, Milwaukee, Boston, and Seattle. These cites often have bad weather, from blizzards to rain and fog. However, each of these cities tops the list of those that see major savings due to solar power installations. And rain helps to keep the panels operating efficiently by washing away any dust, pollen, and dirt. Clean panels turn out the most electricity.

San Francisco is well known for its foggy days with cool weather but rooftop solar power systems in San Francisco do function well. The amount of direct sunlight is reduced by fog and clouds, but as already was said, solar panels function better at cooler temperatures, so the electricity output in San Francisco is still significant. Using a home solar power system there can save approximately $1,500 per year on utility bills.

Germany is the fourth-largest PV market in the world that's famous for its lack of sunlight. Germany accounts for about 25 percent of the world's solar power output and achieved its strongest growth in half a decade during 2018, according to a recent Greentech Media article. 

Going solar is about saving on your energy costs as well as helping our planet and the weather can’t be an obstacle.

And if we choose to rely on solar panels for our home electricity use, we can also use a solar battery system to save money by storing free energy for use when it’s cloudy or for night use. Solar batteries have been around for a while, but up until recently, the costs were very high, the equipment was bulky and they were difficult to use. Except for people who lived off the grid, they weren’t so good investment. But that has changed in recent years. The price of solar batteries has dropped and in many cases, they are now an excellent investment for homeowners in cloudy regions who want to reduce their electricity bills.

Sources: Cleantechnika & Powerhome

                     

Power Your Home with Solar Roof Tiles

Today the main way for homes to harness solar power is still through bulky rigid panels added to the rooftop or mounted on the ground. But inte recent years there are some innovations within the solar PV industry such as solar roof tiles. Solar roof tiles refer to Building Integrated Photovoltaics (BIPV) systems. They blend in better and help deliver clean, green solar power, without the need to sacrifice the aesthetic look and beauty of your home.

Solar roof tiles are made with built-in photovoltaic cells and the color of the solar tiles range from blue to violet to gray and blends well with most colors. Solar roof tiles are connected to each other via MC or other suitable connector type used inphotovoltaics and they work like conventional solar panels. One tile produces about 60 - 180 watts of electricity, and an entire roof could definitely power your entire house. A real hot sunny day could even mean profit for you, excess energy can be sold at a nearby company.

Solar roof tiles are more expensive than solar panels but in terms of the advantages it gives to a local user, it should outweigh the cons. Also, the government offers considerate breaks in taxes for homes that use solar power electricity.

Some of the companies currently producing solar roof tiles are General Electric, PowerLight, Sharp Electronics, and SunPower Corp.

Solé Power Tile, created by SRS Energy, is the industry’s first building-integrated photovoltaic product designed specifically for curved-roof systems and in my next post I'm going to write about it.

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.

Solar PV Power in Cold Climate

Many people interested in generating solar PV power for their household power needs are also interested to know how PV solar panels operate at colder temperatures or in cloudy conditions. Actually, PV solar panels work better at colder temperatures - some of the best efficiencies ever recorded were at the South Pole! This is because the solar cells in the panels are electronic devices that generate electricity depending on the amount of sunlight they receive, not heat. In cold climates, PV panels will generate less energy in the winter than in the summer, but this is due to the shorter days and less sunlight, not the colder temperatures.

Photo credit: altenergy.blog-city.com

PV solar panels continue to work even in cloudy conditions, although they do produce less electricity. On days with cloud cover or windblown snow, the PV panels' output power is reduced significantly. With sun angles approaching the highest limits and visibility being high, the PV panels reach their rated output power.

Many countries in the northwestern region of Europe, including Denmark and the rest of Scandinavia, make extensive use of solar power. Germany is the world's leading installer of photovoltaic (PV) solar cells, although its climate is mostly temperate. Japan is also a major installer of solar PV panels, and their climate is temperate.

An example of integrating PV technology in the daily life are solar powered parking meters which are fairly common in Germany and the Netherlands. The electricity which runs them is supplied by small solar panels on top of the parking meters, right there in the streets.

Canada is another cold-weather country where PV technology is quickly gaining ground. PV cells have been used in Canada over the last 20 years or more for many applications. Photovoltaic modules were used as standalone units, mainly as off-grid distributed electricity generation to power remote homes, telecommunications equipment, oil and pipeline monitoring stations and navigational applications. Over the last few years PV technology has also started to be introduced into urban areas, incorporated into the roofs and facades of homes, offices and factories. And the largest solar PV energy park in North America will be located on approximately 300 acres of land in the Township of Stone Mills, Lennox & Addington County, Ontario. The 19-megawatt project, known as First Light, is being built by SkyPower Corp and SunEdison Canada. The construction is anticipated to be completed by the end of 2009 and local communities will benefit from clean renewable energy sufficient to power more than 2,000 homes annually.

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.

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.

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.

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

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)

Photovoltaic History - Key Milestones in the 1900s (Timeline)

Bell Labs engineer testing solar battery in 1954 Credit: Bell Labs website

1904 - Albert Einstein published his paper on the photoelectric effect (along with a paper on his theory of relativity). Wilhelm Hallwachs makes a semiconductor-junction solar cell (copper and copper oxide).

1914 - The existence of a barrier layer in photovoltaic devices was noted.

1916 - Robert Millikan provided experimental proof of the photoelectric effect.

1918 - Polish scientist Jan Czochralski developed a way to grow single-crystal

silicon. 

1921 - Albert Einstein received the Nobel Prize for his theories explaining the photoelectric effect.

1932 - Audobert and Stora discover the photovoltaic effect in Cadmium selenide (CdSe), a photovoltaic material still used today.

1954 - Bell Labs announces the invention of the first modern silicon solar cell. The scientists Gerald Pearson, Daryl Chapin, and Calvin Fuller develop the silicon photovoltaic (PV) cell at Bell Labs—the first solar cell capable of converting enough of the sun’s energy into power to run everyday electrical equipment. Bell Telephone Laboratories produced a silicon solar cell with 4% efficiency and later achieved 11% efficiency. Reporting the Bell discovery, The New York Times praised it as "the beginning of a new era, leading eventually to the realization of harnessing the almost limitless energy of the sun for the uses of civilization".

1959 - Hoffman Electronics creates a 10% efficient commercial solar cell, and introduces the use of a grid contact, reducing the cell's resistance.

1962 - Bell Telephone Laboratories launches the first telecommunications satellite, the Telstar (initial power 14 watts).

1963 - Sharp Corporation succeeds in producing practical silicon PV modules. Japan installed a 242-W PV array on a lighthouse, the world's largest array at that time.

1965 - Peter Glaser conceives the idea of the satellite solar power station. 

1973 - The University of Delaware builds “Solar One,” one of the world’s first photovoltaic PV) powered residences. The system is a PV/thermal hybrid. 

1980 - At the University of Delaware, the first thin-film solar cell exceeds 10% efficiency using copper sulfide/cadmium sulfide.

1982 - The first, photovoltaic megawatt-scale power station goes on-line in Hisperia, California. It has a 1-megawatt capacity system, developed by ARCO Solar, with modules on 108 dual-axis trackers.

1983 - ARCO Solar dedicates a 6-megawatt photovoltaic substation in central

California. The 120-acre, unmanned facility supplies the Pacific Gas & Electric Company’s utility grid with enough power for 2,000-2,500 homes.

1985 - 20% efficient silicon cell are created by the Centre for Photovoltaic Engineering at the University of New South Wales.

1993 - Pacific Gas & Electric completes installation of the first grid-supported photovoltaic system in Kerman, California. The 500-kilowatt system was the first “distributed power” effort.

1998 - Subhendu Guha, a noted scientist for his pioneering work in amorphous silicon, led the invention of flexible solar shingles, a roofing material and state-of-the-art technology for converting sunlight to electricity.

1999 - Total worldwide installed photovoltaic power reached 1000 megawatts.

Photovoltaic (PV) History - the Beginning

The effect of light on the electric properties of certain materials was observed way back even before electricity became generally available.

In 1839 the nineteen-year-old French physicist Alexandre Edmond Becquerel observed the photovoltaic effect for the first time. Experimenting with metal electrodes in a weak electrolyte or conducting solution (such as salt water) exposed to sunlight, he discovered the appearance of small amounts of electric current.

However, Becquerel's discovery couldn't find any practical use and was limited being tagged as an observed phenomenon. The photo conductivity of an element, selenium, was noted by the English electrical engineer Willoughby Smith in 1873 while he was working with Selenium.

In 1876 William Grylls Adams* and his student Richard Day, discovered that illuminating a junction between selenium and platinum can have a photovoltaic effect. This effect is the basis for the modern solar cell. An electricity expert, Werner von Siemens, stated that the discovery was "scientifically of the most far-reaching importance". The selenium cells were not efficient, but it was proved that light, without heat or moving parts, could be converted into electricity.

William G. Adams published also a paper on the selenium cell 'The action of light on selenium,' in "Proceedings of the Royal Society, A25, 113.

In 1883 Charles Fritts, an American inventor, built what many regard as the first true photovoltaic cell. He developed from selenium wafers a solar cell that had less than 1-2% a conversion rate but represents the beginning of solar technology as we know it today.

In 1887 Heinrich Hertz noticed the photoelectric effect, and published his paper entitled “On an Effect of Ultraviolet Light upon the Electric Discharge.” He noticed that the spark created at a receiving electric circuit increased when ultraviolet light hit the negative terminal.

* William Grylls Adams, an English professor of Natural Philosophy at King's College, London was the brother of John Couch Adams, the astronomer who discovered Neptune.

Photovoltaic Cells

Picture: DOE/EERE

Photovoltaic cells (PVs) (also known as "solar cells") work by transforming light that comes from the sun directly into electricity without an intermediate mechanical device or thermal process. The term photovoltaic is derived by combining the Greek word for light, "phos", with the word "voltaic". The term "volt" is a measure of electricity named for Alessandro Volta (1745-1827), a pioneer in the study of electricity. Photovoltaics literally means light-electricity.

The basic building unit of PV technology is the photovoltaic cell (PV cell). PV cells are made of a semiconductor material, typically silicon, which is treated chemically. When light hits the cell, a field of electricity is created within the layers causing the electricity to flow. This "photovoltaic effect" results in direct current (DC) electricity which is the same type of current produced by batteries.

In order to use this energy in most homes, an inverter is used to change the DC electricity to AC. Once electricity is generated, it can go to power anything in your house or be stored in batteries for later use. The greater the intensity of the light, the greater the flow across the layers and so the more electricity generated. But such a system does not necessary require direct sunlight to work.

Single PV cells are connected electrically to form PV modules, which are the building blocks of PV systems. Depending upon the application, the solar modules are typically wired together to form an array. Individual PV cells – averaging about 4 inches per side – typically converts 15% of the available solar radiation into about 1 or 2 watts of electrical power. Larger modules or arrays of modules are used to generate power for the grid.