Photovoltaic systems is just another way of saying Solar Power systems. As the world’s energy supply dwindles and mankind needs cleaner ways to continue the lifestyle we enjoy now, solar generated power is one of the primary answers to the problems ahead. Any government that has forward thinking is either presently employing an incentive program such as Germany now has called the Microfit and Fit program respectively. The term FIT stands for feed in tariff which essentially means feeding power into the power grid and getting some money or value for it. There are two methods of keeping track of the energy produced and figuring out the compensation. Both utilize the standard electric meter at your home. One way is called net metering which simply spins your meter backwards or the other method is to install a completely separate meter such as is the case in the Canadian Ontario Solar Program.
Solar generation is a direct conversion of solar energy from the sun into electricity, and has only been discovered a little over 50 years ago. The unique properties of certain types of semi-conductors to convert the sun’s radiation into electricity is at the root of this technology. Typically crystalline silicon that is combined with small dopings of other compounds to create wafers that are sensitive to sunlight and produce a small DC voltage make up a typical solar cell. These cells are thin wafers (solar cells) cut to approximately 5 inch squares (most with corners cut diagonally) , and they are combined together to form a solar panel. Solar panels then are combined together to form a solar array. Solar arrays can be quite large and easily cover most of a homes roof or in ground mount situations even a larger area. A solar system includes all the solar arrays wired together and all the other hardware necessary to convert and control the energy for use either off the grid as a self contained system or feeding the grid for monetary gain. The most common system is a grid feeding system hooked into the local utility. Systems that are stand alone off the grid types usually have batteries to store daytime energy for use after the sun goes down.
Electrical hardware such as inverters (change DC to AC), charge controllers, disconnect boxes, combiner boxes, revenue meters, and of course wire make up most of the rest of the system. There is also a mounting system necessary to hold the solar arrays on the roof or ground. Solar tracking may also be employed to have the array follow or track the sun as it moves across the sky thereby increasing the amount of energy captured daily.
It should explained now that solar panels produce DC or direct current electrical energy. Batteries also store this same type of electricity. A stand alone off the grid system could just use that energy if the right type of appliances (called loads) are used instead of the standard ones found in a regular home. Most RV’s have DC appliances in them and there are stoves, fridges and other appliances that you could never tell from just looking at them that they are DC powered. For systems that feed the grid they must take the DC energy and change it over to AC or alternating current electrical energy of the same voltage and frequency. In North America that frequency is 60 hertz. Grid voltage varies from country to country. Inverters are the device that converts DC to AC and there are many different types of inverters available for a wide range of systems.
There are many advantages about generating electrical energy using a PV system (solar system). The most obvious one is the displacing of the generating systems presently employed that we will call the polluting types such as coal or nuclear. If you can’t get a grid connection for example to a cottage with out costing a small fortune to have poles installed and lines, then a solar system is ideal to handle a remote location. Of course the pride of knowing you are creating a green energy is growing in popularity, there is no noise like wind generation, and no moving parts. For some people employing a PV system makes a personal statement about protecting the environment for future generations. PV arrays are adaptable and can be expanded as needed. With no moving parts these systems are highly reliable and last a lone time with very little maintenance. Electrical independence is also achievable with a large enough system and reduces the dependence of the consumer on power outages. Harnessing the power of the Sun is free, cheap electricity, and readily available. Conventionally generated elecricity is expected to continue to rise in price (measured in kilowatt hour) while solar generation and the cost of solar cells will continue to reduce in price and improve in efficiency. Keeping this in mind solar energy is a good hedge against paying exorbitant fees for your electricity.
There are some disadvantages to solar systems (PV systems) that have so far limited their use. The high initial cost to purchase and install a system compared to the government subsidized cheap electricity we presently enjoy (when available). Of course you need to have a southern exposure clear enough from trees and other structures to generate a decent amount of energy. Arrays need to be large enough to capture the energy and take up a size able amount of space. There is presently an ignorance of many people in North America as to the potential that can be achieve by the employment of a solar system (pv system). Finding qualified solar installers in your area is another problem as this industry is in its infancy. The electrical grid infrastructure and the unwillingness of some local utilities to allow hook up to the grid is a problem. Many electrical inspectors are untrained to adequately approve an installation. Many leaders in the PV industry are working on solving these problems as they continue to promote solar energy. Provincial and Federal governments are creating incentive programs to off set the cost of installation. Most important by far is to educate the general public about solar energy and is the main reason why you will find this website to be the definitive knowledge base that is free to read. Much of this information comes from personal experience of this author (Thomas Collins) and referencing some expensive textbooks that have been purchased and read by this author.
Let’s explain about the electrical grid that we presently have and how it will change over time as more and more electrical energy is fed into the grid by many home owners, commercial buildings, and even solar farms. Presently we have an electrical distribution system that services millions of homes and businesses from a relatively small number of large power plants. A utility is a company that can produce and/or distributes electricity in a geographic region, province or state. The grid as it has come to be called is the entire system of wires, substations and transformers that distributes electricity from the power plants to the consumers. The grid is regional and each region is connected together. Electricity can travel hundreds of miles to reach your home or office from the power plant. If one region goes down due to inclement weather or overloading, then another region may supply the area effected until the region is up and running again. As solar system implementation continues we will have a smaller distributed generation system where the power generated may only travel a few feet to reach the consumer. An advantage to this system is the elimination of power loss created by the long travel lengths of transmission lines. Distributed generation includes of course PV systems, wind turbines, engine generators, and other micro hydro water generation systems. The future looks bright (no pun intended) for solar power generation. This will change the landscape of local utilities as well as the landscape of how homes will be built in the future. This author sees a day when all homes will have their roofs set up for a southern exposure. Picture if you will all the homes on a crescent with their roofs elongated on one side all pointing south. The spacing of homes and larger buildings not being allowed to be built because of blocking some one’s sun exposure will be an issue. Strategic planting of trees and the pruning back of them will be needed as sun exposure becomes a major issue. I see the day where neighbors will take legal action to prevent the planting of trees in some areas around their homes. You may not see those nice old neighborhoods where large maple trees dominate the street sculpture. Solar panels don’t like shade.
So lets talk a little bit about the history of solar energy. It’s been around for about 160 years but used sparingly until the last 20 years or so and is growing at an exponential rate now. A fellow named Edmund Becquerel is the father of solar energy and discovered the photovoltaic effect at 19 years of age. In 1839 he observed an increase in voltage when two electrodes submerged in a conductive liquid solution were exposed to light. There was no practical use for this discovery at that time so solar energy production remained dormant. In 1873 Willoughby Smith observed a similar happening when selenium was exposed to light when underwater. This observation of photoconductivity led to experimentation. The first PV cell or solar cell was developed by Charles Fritt in 1883. He covered a selenium substance with a thin layer of gold, and produced a tiny electrical current with an efficiency of only 1% which is impractical for power generation. Selenium is also very expensive thus making it impractical cost wise to bother with. In 1954 Darryl Chapin and a group of researchers at Bell laboratories were looking for a remote power source to use in telephone applications. Their efforts failed as they continued to try and use selenium. Fellow Bell researchers Calvin Fuller and Gordon Pearson were attempting to create the first transistors with silicon. They discovered adding certain impurities to the silicon cause a semi-conductor effect. This same substance when exposed to light also created a voltage difference that eventually these two men created the first usable solar cell. It was called a solar battery. The efficiency of these first cells were around 6% (small by today’s efficiency) and a significant enough development to warrant further research. The space race in the late 1950′s and 1960′s caused the need to develop solar energy production. PV cells are ideal power generators for satellites and space craft. Almost every space craft after 1958 employed the use of solar energy generation. The telephone companies used solar energy for remote telephone stations and radio transmitters. Now with rising oil prices, coal prices, and the concern for the environment solar has become a viable alternative. Mass production has brought the price per watt down to the 4 dollar per watt area and will continue to reduce that figure over time as more and more manufacturers come on line. Also cell efficiencies are increasing every year. We are now around 14 % efficient for most silicon based cells. Some manufacturers are claiming 18% and price them somewhat higher.
Let’s explain the efficiency in layman’s terms. Basically it is agreed by the scientific community that one square meter of solar energy has the ability to produce 1000 watts of electrical energy if the solar cells the sun light shone on was that size. Presently we get about 14 % of that 1000 watts or 140 watts of energy. Watts = volts x current so 140 watts = let’s use 24 volts as an example x current. Therefore 140 divided by 24 = 5.4 or 5.4 amps (current is expressed in amps). Many solar panels are built up in 24 volt increments.
PV Applications have grown exponentially over time from mainly being used in space power applications to now being used by most people in the modern world. Solar powered calculators were one of the first most widely used applications. Now there are solar lights in many neighborhoods lighting up front yards, backyards, farmers lanes and any other place that needs a cheap easy way to provide lighting. As PV efficiency continues to increase while the cost to purchase solar cells, panels, and arrays have decreased more and more applications for solar PV have emerged.
Today Photovoltaic systems can be used in most any application that DC voltage is required. With the continuing developement of inverter technology (changing DC to AC) the number of applications are even more enhanced. Solar systems can be a simple module connected directly to a load with no other requirements or it can be a complicated system with multiple power generating sources feeding into the grid.
Space the final frontier is an example of the most remote solar installations. Luckily space has even more solar radiation available to produce energy. Satellites were the first real opportunity for solar applications to be used in outer space. Space photovoltaic cells are much more efficient and expensive than the typical solar cells used presently for residential systems.
Portable Solar Panels power mobile equipment such as the emerging electric vehicle market. Portable solar signs and lighting as well as many handheld electronic devices are other typical applications now in use. Of course if the portable piece of equipment requires use after the sun goes down, a battery is usually tied into the system and charged with excess energy while the sun is available.
Most portable photovoltaic systems are generally small and provide rather small amounts of energy to light loads. Because the idea is to be portable the systems are also light weight. They also need to be positioned correctly each time they are moved so they capture the suns rays, sometimes 4 or 5 times daily. They can be used in motion but may not work to their maximum potential if they are not always in direct sunlight.
Motor homes and water craft use solar systems as well. Quite often they are used as back up systems to help when needed. Small gasoline generators will usually be used when a large supply of energy is required, while the solar system with batteries will power other things that take less power to operate.
Portable signs for construction zones warn motorists of various speed requirements and detours. Portable lighting for short road work projects that take place in the evening may be chosen over hooking lights to the grid or bringing in a portable generator.
Personal electronic devices such as GPS, cell phones, radios, calculators, and flash lights are just some of the growing list of devices being powered by solar.
Back up Residential Power systems in the even of brown outs or black outs particularly in the winter months where cold weather persists are now available to purchase. These systems can keep a refrigerator going, provide lighting, communications, water purifying, water pumping and just about any other load necessary until the grid is repaired.
Remote locations that are too far from the grid and expensive to bother hooking up are another real life example of PV capabilities. Off the grid homes are on the rise as people want to get away from paying electrical bills and have an endless source of cheap electricity. Solar systems can be properly set up to provide all the power a regular home requires, although most of these homes will have a few different power generating sources and a gasoline or other fuel generator just in case of some problem arising as lack of sunlight for an extended period of bad weather.
Solar lights that use LED technology are the best suited solar power lighting system to employ in a solar home.
Utility interactive solar systems are ones that will feed into the grid and make some money for it’s owner as well as provide back up power in the event of power failures from the grid. Money is generated in two ways. The consumption meter will spin backwards when the home is feeding the grid or a separate meter called a revenue meter will spin when the grid is being supplied. The main difference is the backward spinning meter will only bring an electrical bill to zero if it can and the revenue meter will continue to feed the grid and generate money. Both meters are read as usual and the bills for the spin back type system are adjusted, while the separate meter a cheque is sent out in the mail along with a consumption bill.
Utility Scaled Solar Systems are now beginning to be put on line supplying the grid with levels of power surpassing 10 megawatts. These systems use many solar panels set up in arrays and cover large areas of land or roofing. In places such as Ontario Canada the microfit incentive program has spawned many of these solar farms as they have become to be known. In fact at present the largest solar farm in the world is located in Ontario Canada near the city of Sarnia. Advantages of these solar farms are that they can be built, installed and on line in very short order compared to a coal fired or nuclear plant. A typical solar farm of 10 megawatts may cost in the area of 50 million dollars to implement. With a Feed In Tariff program in place these systems will generate 3 -5 times the investment back for the owner, and after the 20 year contract is over they continue to generate energy indefinitely. Many of these larger systems may employ sun tracking devices that help improve their output. These type of power plants can be located closer to populated cities with out the worry of a nuclear accident as they are completely safe with no moving parts to make noise like a windmill.
The PV Industry is made up of a number of combined disciplines. From research institutions, pv module manufacturers, integrators and installers, solar training schools, pv system sub component manufacturers, structural engineers, electricians, as well as utility companies all combine their skills to provide a finished product to the consumer. Integrators are like the main contractor when a system is to be installed. They call on a solar site analyzer to check out the site and gather data to decide if the area of installation is suitable. This process involves checking out what the solar arrays will be mounted on. If it’s a roof, the general wear and tear of the roof needs to be considered as well as how much sun will be available on a yearly basis, and this term is represented in yearly sun hours. Shading is another element of site analysis that involves using a sun path device that is set up for the specific latitude of the site in degrees. For example the Southern Ontario Canada area is located in the latitudes of 43 degrees to 46 degrees. Shading can be caused by trees, other buildings, vent pipes on roofs, or even hills and mountains. Once a site is checked out the integrator will crunch the data and present a rendering of it to the potential customer. Moving forward the integrator would be involved in pricing and quoting the system. The integrator may look after the entire installation or sub contract it to various solar installation companies. Sometimes this could be a roofing company that has added an extra business arm to it’s offerings and sometimes it may be a dedicated solar only installer. Of course permits are needed on a few fronts. The integrator may get involved with filling out applications for microfit with the customer as well as obtaining the approval to hook into the grid from the authority having jurisdiction, or local utility. In Ontario Canada the local utility provides the approval to hook into the grid combined with the Provincial authority called Hydro 1. A structural engineer is also required to stamp his approval on the project if it is a roof mounted system. For ground mounted systems you may also need an environmental assessment if it is a larger project such as a solar farm. In summary the Integrator is central to all applications necessary to gather the approvals necessary.
Installers are vital to having a quality system installed. These individuals should have quality workmanship in both mechanical and electrical talent, because of the uniqueness of solar components and interfacing all of the system properly. Solar installers should have training from a recognized institution such as the Ontario Solar Academy and this author believes a NABCEP (North American Board of Certified Energy Practitioners) certification is a minimum requirement to choose a qualified installer. Solar installation is so very new and there are a number of entrepreneurs who have entered the solar installation business with out proper training. This is a problem for an unsuspecting home owner who wants a hassle free install. I recommend all people who are contemplating having solar installed on their properties to verify who will be installing the system.
NABCEP is an organization created by solar professionals and scholars with the aim of standarizing solar installation qualifications. A NABCEP installer has quality credentials gained from both education and experience that is essential to a quality installation. Certification is awarded to individuals who pass a lengthly exam after taking a course such as the Ontario Solar Academy offers. NABCEP is voluntary to achieve but shows beyond a shadow of a doubt the professionalism of an installer. I would personally steer clear of anyone who wants to install a solar system for you if they don’t have this designation in both the United States or Canada. There are some other organizations attempting to copy NABCEP but all imitations are as far as this author is concerned BOGUS.
There are standards and safety guidelines for the PV industry from a number of other organizations that are involved in one way or another. UL (Underwriters Laboratory) CSA (Canadian Standards Association) IEEE Institute Electrical Electronic Engineers publish standards for the solar industry. Everything from how to test a solar module to methods of measuring solar radiation, making proper electrical connections, grounding of the system and many other topics are addressed by these organizations. The National Electrical Code (NEC) for the US and the Canadian Electrical Code are the defining guidelines to follow for the actual electrical connection and wiring of the system. Article 690 of the NEC specifically details the design and installation of a solar system. Section 50 of the Ontario Electrical Code does the same for Ontario and Canada. Each has slightly different rules to follow so a master electrician is always a good idea to employ for the final pre inspection and testing.
CSA and UL as mentioned above test the solar panels for use in North America. UL puts a C with their emblem for use in Canada and CSA puts a US with their symbol for use in the US. Both agencies simply use their symbol for their originating country. In short never purchase a solar panel with out one or the other agency emblem easily visible on the back of the solar panel. This goes for inverters and any other electrical box such as a combiner box or DC shut off box.
Authorities having jurisdiction is a term mainly used in the United States which stands for the organization in general who looks after the final inspection of the entire system before it can be turned on and feed the grid. In the United states this responsibility falls on different levels of government in different states and areas with in the states, hence the term was made up to capture all possible scenarios. In Canada this responsibility falls on the provincial hydro inspection agency. In Ontario for example this agency is the ESA or Electrical Safety Association. These inspectors have final say on any project in Ontario. If they don’t like something you must change it to meet their requirements.
There are other ways or combinational ways to capture solar energy. So far we have only mentioned photovoltaics using semiconductors. You can also use mirrors to concentrate the sun’s light with parabolic mirrors used to heat liquid, create steam and drive a steam engine system which transmits it’s rotary power to an electrical generating dynamo.
Many of the homes being designed today use passive solar techniques to take advantage of the sun light as well as the seasons. R2000 type homes that are essentially well insulated and air tight are becoming sought after by home buyers who are savy. Positioning of windows to allow sunlight in during the winter months helps warm the home. If too much sun in the summer is a problem then a simple planting of a deciduous tree may solve the problem, shading the window in the summer months and allowing sunlight through in the winter when it has no leaves. There is an organization call LEED (Leadership in Energy Environment and Design which gives ratings that certifies different levels of energy efficiencies and environmental protection.
Solar thermal energy systems use liquids to convert solar energy into heat energy. The heat in the liquid is pumped out of a solar collector into a reserve area to be used for hot water or home heating or even to heat a swimming pool. These systems can be scaled to many different sizes and applications. These systems can be passive or active. Active systems use pumps and fans. In passive systems the liquid flows by convection principles. Solar cookers are small scale ovens that utilize concentrating reflectors to direct sun light into a dish area or box.
Solar Chemical Energy is a fairly new technology as well. This is taking advantage of photosynthesis. Plants perform this action daily. An indirect example of solar chemical energy is through bio fuels such as biodiesel.