Understanding Solar Power
Solar power can be understood as the production of electricity from sunlight. There are two ways of harnessing solar power namely direct and indirect. Photovoltaics (PV) is the most common method in which sunlight is used to create electron flow in a photovoltaic cell. The other indirect way of generating electricity from sunlight is done by focusing the sun’s energy to boil water which is in turn employed in producing power.
Sun is the primary source of all energy found on this planet. Sun has been sending abundance of photoelectric energy to power our earth. There are easy and commercially viable ways in which solar energy can be converted into electricity to power any type of requirement that we can name on this earth. Though the human race has accomplished incredible feats in science and technology, to this day, the civilization continues to bank on highly polluting and hazardous fossil sources to produce electricity. Thanks to the growing concerns regarding the over use of non-renewable resources and the environmental hazards caused by conventional fuel sources, today we have increasing number of homes, industries and corporate turning towards solar power as one of the available alternative sources of electricity.
Solar energy is available everyday in incredible measures and will never get depleted at any point of time. There are several advantages of using solar energy to meet our electricity needs including the facts that it can prove to be cost-effective and non-polluting. The fast growing solar power industry can assure a promising future for this alternative power source besides effectively meeting the growing energy demands of today’s world.
Basics and History of Solar Electricity
Solar electricity producing devices have been there for more than 50 years. However, devices known as Photovoltaics or PV are still deemed to remain at the cutting edge of this technology. So far, a number of scientists and businessmen have been dreaming of offering the world the promise of unpolluted, economical, and plentiful electricity from the sun. This motivation has been instrumental in bringing out a number of discoveries and rapid advancements in the solar power arena.
PV Technology Today
Photovoltaics (PV) otherwise known as solar cells can be defined as semiconductor devices that can convert the energy gathered from sunlight into direct current (DC) electricity. As per the existing technology, required numbers of PV cells are electrically configured into units and groups that can be used across a variety of electricity needs including charging batteries, operating motors, and powering a number of electrical loads. PV systems are combined with appropriate power converting equipments to generate alternating current (AC) that is fully compatible with any conventional electrical appliances. The power thus generated can also be operated in parallel with or interconnected to the conventional utility grid.
History of Photovoltaic cells
Commercially viable photovoltaic cells were first manufactured in the late 1950s. In 1960s these were primarily used to supply electrical power to manage the operations at the earth-orbiting satellites. In the 1970s, significant advancements were achieved in manufacturing process of PV cells in addition to the performance and quality of PV modules. This development in fact helped in bringing down the costs of PV cells and also opened up a host of opportunities for supplying power to remote terrestrial applications, like battery charging needs for signals, navigational gadgets, telecommunications devices and a number of other critical, low-power requirements.
During 1980s, photovoltaics technology found a prominent place among the popular power sources and consumer electronic devices like calculators, watches, lanterns, radios and a number of small-sized battery-charging applications. During the aftermath of the energy crises seen across the world during 1970s, commendable progress was made in manufacturing PV power systems for use at residences and commercial establishments, both as stand-alone, remote power or utility-linked applications. During the same time, global applications also evolved for PV systems to manage the power needs of rural health centers and for a variety of needs including telecommunications, refrigeration, water pumping, and off-grid households. Today, the applications of PV products have dramatically increased to become the major chunk of today’s world market for PV products. Today, the industrial manufacturing of PV modules has grown at about 25 percent annually. In addition, a number of important programs in the U.S., Japan and Europe are fast developing the implementation of PV systems on buildings and in interconnecting PV cells to the utility networks.
The Working of PV Cells
The most common silicon PV cell consists of a thin wafer made of an ultra-thin layer of phosphorus-doped (N-type) silicon fixed on top of a thicker layer of boron-doped (P-type) silicon. At the P-N junction or the point where these two materials come in contact, an electrical field is created near the top surface of the cell. As the sunlight falls on the surface of a PV cell, the electrical field thus generated gives momentum and direction to the electrons stimulated by the light which results in the flow of current is the total set up is connected to an electrical load
Irrespective of their size, each of the commonly available silicon PV cells can produce about 0.5-0.6 volt DC under the conditions of open-circuit, no-load. The amount of current and the power output ensuing from a PV cell totally depends on the efficiency of the cell and its surface area. It is also proportional to the intensity of sunlight that strikes the surface of the cell. For instance, when the sunlight that strikes the cell is at its peak, a commercial PV cell reported with a surface area of about 160 cm^2 (~25 in^2) can generate about 2 watts peak power. However, if the sunlight intensity was only 40 percent of the peak, then the same cell can generate only about 0.8 watts.
Types of PV Systems
Generally, we can classify photovoltaic power systems with regard to their functional and operational needs, configuration of their components, and the way the equipments are connected to other power generating sources and electrical loads. All photovoltaic systems can be grouped under the two heads of grid-connected systems and stand-alone systems. The grid-connected systems can also be called as utility-interactive systems. Photovoltaic systems can be manufactured to supply DC and/or AC power service. They can operate either while connected with or independent of the utility grid. PV systems can also be connected with other existing energy sources and power storage systems.
What are called as grid-connected or utility-interactive PV systems have been designed in such a way that they operate parallel to and interconnected with the conventional electric utility grid. The main segment in grid-connected PV systems can said to be the inverter also known as the power conditioning unit (PCU). The principal function of the PCU is to convert the DC power generated by the PV array into AC power that is compatible with the voltage and power quality needs of the utility grid. The set us is designed to automatically stop the power supply to the utility grid when it is not energized. A typical set up also features a bi-directional interface established between the PV system AC output circuits and the electric utility network, which is generally found at an on-site distribution panel or at the point of service entrance. This set up enables the AC power generated by the PV system to supply the needs of on-site electrical loads, or support the grid at times when the PV system output becomes greater than the demands of the on-site load. During nights and at times when the electrical loads remain greater than the output by the PV system, the balance of power needed by the loads is supplied from the electric utility. This is the most important safety feature required by all grid-connected PV systems. This arrangement ensures that the PV system will cease to operate or feed back into the utility grid at times when the grid is shut down for service or repair.
Applications of Solar Power
According to the user’s requirements and the location where a user lives, there are a number of solar power systems.
On Grid or Grid-connected Solar Power Systems
Grid-tied solar power systems are most common in cities, industrial areas and suburbs of cities. This system can be installed at places where utility-generated power is available. If a user requires more electricity than what is produced by the solar power system installed by him, it can be supplemented by the solar powered electricity with the utility-generated energy. At the same time, if the solar power system installed by the user is able to produce more power than what is consumed by his requirements, the user can sell the excess of generated power to other customers. As a result, the good done by the user by resorting to solar power does not stop with his industry or household, rather he is able to extend this benefit to other users as well. In this way, the user is also able to offset the utility-generated power consumed by him during nights.
Grid-Tied Solar Power Systems featuring battery backup
Under this set up, solar energy panels are fitted with batteries and generators meant for grid-tie applications. This set up can bestow the advantages of the clean energy produced by the solar panels with that of the energy stored in batteries for use during extended power outages and nights. Solar panels generate electricity while the sunlight is available and the batteries are charged. If the user requires more power or if the batteries start running low, the natural gas generator starts off to recharge the batteries. The generator shuts down automatically once the batteries are charged to full.
Off-Grid Solar Power Systems
Off-grid solar power systems otherwise known as standalone solar power systems comprise of solar panels connected to a battery bank. Such set ups are very common to rural areas and regions where the users do not have access to the utility grid. Off-grid systems are also useful at places where it is difficult or costly to bring in the grid. Most people go for this type for the advantages of battery back-up if they feel that the power is unreliable or there are impending power outages. Often adding a solar energy system is cheaper than getting connected and to pay continuously for using the utility power. The excess of power generated at times when the sun shines is stored in the batteries for use during times when the sun does not shine. The advantage of this system is greater independence while the disadvantage includes greater complexity and greater cost.
Direct DC Solar Power System
Direct DC solar power systems are simple systems that produce energy as and when it is required. Some of the most common uses of this system are supplying the power required to operate water pumps and fans. The best advantage of this system is that it does not require complex wiring as it does not have storage and control systems attached. Small sized systems of this type are easy to install and transport.
Hybrid Power Systems
Hybrid power systems are a combination of a number of sources that generate electricity. These are best suited for electrification. The commonest modules of this system are solar and wind technologies. Since sun and winds vary seasonally, often they can be complementary to each other in assuring non-stop power supply.
Advantages of Solar Power
The first ever commercial application of photovoltaic cells started about 50 years ago when these systems were employed in supplying the power consumed by the communications satellites in near-earth orbit. Eventually, the cost of solar energy technology significantly came down while its efficiency grew to incredible heights. As a result, these systems have today entered almost all practical applications on this earth right from supplying power to personal electronic devices to meeting the requirements of homes and factories besides producing utility-scale power.
Solar energy holds immense advantages for powering satellites since they can be easily launched into orbit without the hassles of heavy storage units for fuel supply. Over and above, the advantages of solar power for our earth are even more as solar-generated energy assures pollution-free energy in abundant measures which does not rely on costly fuel-delivery infrastructures, foreign affairs, big businesses and the price machinations of broking firms.
Solar power production supplies energy as and when you require it, while it is completely scalable to meet your power needs. Solar energy cells are highly reliable and very easy to maintain since they do not have any moving parts.
Implications of Using Solar Power
Unlike other power producing technologies like fossil fuels, solar power technology does not result in any harmful emissions while in operation. In most cases, we depend on non-renewable energy like fossil fuels to manage the energy requirements in manufacturing and transporting renewable energy technologies, thereby causing carbon emissions. If solar power is employed to manage the above said needs, 1-kilowatt system can eliminate the burning of about 170 pounds of coal and saves about 300 pounds of carbon dioxide from being pumped into the atmosphere. In addition, this can also save about 105 gallons of water consumption per month. BP Solar has two facilities at Maryland and Virginia built by Solarex in which solar panels produce all the energy required to manufacture solar panels.
Among all the renewable energies, solar electric production is credited with the highest power density. Solar power is pollution free even during its use. Existing pollution control methods can easily help in managing emissions and production end wastes. Over and above, end-of-use recycling technologies are fast developing.
Once the initial set up is done, PV systems can function smoothly for several years with almost no maintenance and little intervention. When compared with other power technologies, the costs involved in the operation of PV installations are significantly low. At places where fuel transport or grid connectivity is challenging, solar power is economically beneficial. Some of the most important examples under this head will include island communities, ocean vessels, remote locations and satellites. Use of grid-connected solar power eliminates energy losses during transmissions besides greatly supplementing the consumption of conventional power.
There are however a few disadvantages in depending on solar power. The cost involved in the initial set up of PV systems is rather very high. Solar power is not available during nights and cloudy weather conditions. This necessitates the installation of storage system or complementary power system. Solar cells produce only DC current which needs to be converted into AC current by installing a grid tie inverter. This accounts for about 4 to 12% energy loss.
Popular manufacturers in the Solar Power Industry
Solar panels are the most important constituents in solar power equipments. Some of the leading manufacturers of solar panels are Big Frog Mountain, Solar Cell Sales and Mr Solar. These companies manufacture the basic solar power generating kit comprising of a solar panel fitted with batteries and other accessories. To generate electricity the users will not require any special equipment, an air compressor for instance. The other popular companies that manufacture solar power generating kits include Kyocera Solar Power.
A firm called evergreen solar manufactures photovoltaic modules that are used in the construction of very big solar installations. Solar Attic and Go Solar are two popular firms that design, manufacture and install solar heating equipments meant for homes. They also supply solar heating equipments meant for swimming pools. These firms also offer a continuous after sales support services.
Some important players in the solar power industry have championed the production of wireless solar power. SunWize technologies Inc. is a notable one in this segment. These equipments are suseful to generate environmentally friendly power with great ease.
Solar energy is also useful to operate race cars, aircrafts and space craft. Around the world, Solar power companies are producing silicon solar cells that are employed in these applications. Nanosolar manufactures roll prints of solar cells that are thinner than silicon measuring just 1/100th of it. Â Solar technology proves to be highly appropriate to establishments at remote locations, especially like livestock farms.
A number of companies across the globe manufacture parking lots, solar powered street lights and billboards. A number of other companies manufacture solar energy products for personal use like calculators, laptops and computers.
Industry Overview and Future Prospects
Storage batteries charged by solar power have been enjoying a great demand since long at off-grid locations. The first ever commercial kit of this kind was installed in 1966 at the light house of Ogami Island in Japan. The installation made it possible to change the gas torch used earlier to electrical power.
The solar photovoltaic (PV) installations across the globe reached 2.826 gigawatts in 2007. In about one year’s time in 2008, there was a dramatic increase to 5.95 gigawatts marking a 110% rise. During this time, Germany, Japan and the US were said to be the leading countries in installing PV systems totaling to about 89% of the globe PV installed capacity. Navigant Consulting and Electronic Trend Publications have estimated that in 2012, the worldwide PV installations will reach 18.8GW and 12.3GW respectively. Over the past three years, there is a significant increase in the manufacture of solar cells and modules.
In the years 2006 and 2007, Germany remained the fastest growing major PV market in the whole world. By the year 2008, the country had installed about 5.337 GWp of PV systems which was in fact 35% of the world total. The potential PV industry in Germany has given rise to more than 10,000 jobs in the segments of PV systems production, marketing and installation.
The EPIA or Greenpeace Advanced Scenario has reported that by 2030, PV systems would be producing about 1,864 GW of electricity across the world. This fact indicates that if a sincere commitment is ensured towards the initiatives made in the lines of energy efficiency, the total solar power production of the world in the next twenty five years will be able to meet the needs of about 14% of the world’s population.