Photovlotaics then, now and in the future

Published on Mon, 05/10/2010 - 9:03am

Photovlotaics or PV power has been around for a good many years in some form or another. It is commonly referred to today as solar power and is distributed in the form of PV modules, which are also referred to by another commonly used name: solar panels. It is most typically priced by the watt and there are many different panel sizes and different wattages and voltage configurations.

Many people have seen the old solar water heating panels and solar air heating panels on the roofs of houses located throughout our country. Some associate these now discolored, and unusable in many instances, panels with PV power. Yet the only thing they have in common is they both rely on the sun to do the specific job they were designed for. There is a tremendous difference though. They are really nothing alike. Those heating systems did not create an electrical current, but merely harnessed the sun’s heat energy, and used it either for water heating or climate heating within the home. They are referred to as thermal collectors, and there have been vast improvements in that technology just as there have been with photovoltaics. Photovoltaics, however, is the actual creation and harnessing of electrical power from the sun’s rays shining on photovoltaic modules. This technology creates a DC electrical current that can be stored in batteries or used under direct load during daylight hours for numerous applications.
A brief history on the invention of photovoltaic cells and technology follows. It was over 160 years ago in 1839 at the early age of 19 that a French physicist by the name of Antoine-Cesar Becquerel, who is also noted in some references as Edmund Becquerel, noticed that when light struck two electrodes submerged in a conductive solution, a small but measurable electric charge was created. This became known in scientific circles as the photovoltaic effect. Due to the lack of practical uses for electricity at that time in history, his discovery went basically un-utilized for more than a century. In 1883, American Charles Frits created the world’s first PV cell using selenium as a conductor in a wafer form and covering it with a thin gold film. The problem with using selenium was that it was rare and very expensive and the overall efficiency of the cell Frits created was less than one percent. That was not nearly efficient enough to be used in a practical fashion to create usable amounts of electricity. It was in 1941 that American Russell Ohl accomplished the task of slightly improving the PV cell by replacing the conductive solution with which the cell was made he replaced the selenium with silicone. Ohl’s cell shared the same problem as Frits’ cell however in that even though it replaced selenium with silicon and silicon was a less expensive material in its making, its efficiency still did not exceed one percent.
It was in 1954 that three men working for Bell Laboratories worked together and increased the efficiency of solar cells considerably and created the first solar panel using silicon cells. They referred to it as a solar battery even though it did not store electricity as batteries do. They began their search for increased efficiency to produce a product that they hoped would power remote telephone service stations. Through their combined efforts, the efficiency of the solar cell was increased to 6%. This was not that remarkable or noteworthy compare to today’s solar cell standards, but was a vast improvement over the early cells that were created by
Frits and Ohl. These three gentlemen, Darryl Chapin, Calvin Fuller and Gordon Pearson, are credited with creating the first useful PV cell under the funding and employ of Bell Laboratories.
It is perhaps worth mentioning at this point that there were many other individuals who played a vital part in the development of the PV cells through their research and testing of the many parts and pieces and conductive solutions that were involved in the processes that lead to the current solar cell. They and their processes are simply too numerous to mention here.
The initial growth of the PV industry was severely hindered by the extremely high cost of the solar panels themselves and their lack of efficiency in the early years. The initial cost of a handmade solar cell was around $1,000 dollars per watt in the early 1960s. One of the only entities that felt they could justify the expense initially was the US government agency NASA. The United States government was in a race against Russia to improve space technology at that time, and there were not many options to power the machines responsible for that technology in outer space. Photovotaics actually made sense as a power source in those outer space applications, even at the elevated prices. PV modules were used as power plants on spacecrafts and satellites. There is certainly no shortage of sunlight in outer space so they were and still are today a perfect fit with space machines. With few exceptions, PV cells have been on every spacecraft or satellite launched since they were first sent up on the Vanguard 1 satellite in 1958.
Back here on the ground, PV power would get its start on remote telephone systems and radio transmitters where normal AC electrical power wasn’t a viable option because distance lines would have been needed to be run. It allowed new forms of communication to be brought to some of the most remote locations on the planet. As the technology progressed and improved, it allowed the use of PV power for remote water pumping and lighting in villages and remote home sites where many people had previously lived without electricity of any kind.
Many factors have increased the demand and affordability of solar power throughout the years and have fostered growth in the PV industry. The ever-rising cost of fossil fuel production and its limited resources are not the least of these. Another contributing factor is the clean and green mentality that is becoming a more popular way of thinking around the globe. This type of thinking is being highly subsidized by the world’s governments when put into action by consumers who actually purchase green energy solutions such as solar and wind power. Tax incentives are available in several countries around the globe, and certainly in most states in the United States for purchasing green energy and utilizing it for both business and residential energy needs alike. Tax incentives are nothing new when it comes to solar power or renewable energy research. As early as the 1970s, the US government was allowing tax credits for the development of renewable energy products. Through this development process period, incredible improvements were made in the efficiency of PV cells and their production. It is an ever-changing process, but the prices have gone from $1,000 per watt to less than $5.00 per watt to manufacture these panels, and it’s amazing that with such a drastic decrease in price, the quality has increased tremendously. Things are looking very bright in the solar industry today and there is no telling what the future has in store for this great technology. It is almost mind boggling the things that have been invented and the improvements that have been made to an already wonderful technology.
Solar fits into the green energy scene as well as anything available. It has no moving parts, makes no noise and creates zero pollution. This, as well as its many other beneficial attributes, makes it a favorite choice among those looking to improve their negative energy footprint on the planet. With the ever decreasing cost of solar and the incentives available, it is hard to see that in the near future almost every home and business will be able to be at least partially powered by some type of PV system for a portion of their electric needs. The possibilities are absolutely endless, from powering a portion of the lights in an establishment or dwelling to powering the entire energy demand on either one.
How a couple of the more involved PV systems work today, and how to utilize them. It seems that many people have a different opinion about what the best way to utilize a solar powered system is when it comes to a home or business. Many believe that a grid tie system is the best for benefiting the end user and getting the most return on the investment. While others feel that a stand-alone system having nothing to do with traditional grid tie power companies is the best way to go. The actual answer probably lies in what the end user wishes to achieve from their system and their purchase, and what level of independence they want from the traditional power company.
To fully understand the benefits of each style of system above, we must first understand the differences between them. A grid tie system is a system that takes the power from the solar panels and does one of two things. It either utilizes the available power that is demanded at the time from the load and then sells any excess power back to the power company by feeding it through the electric companies power lines, or it sells all of the power back to the power company and lowers the electric rate the owner of the PV system pays to the power company by the amount of power that was sold back.
How PV Technology Relates To Farms & Ranches:
Probably the most common way that this photovoltaic technology has been and is being used on farms and ranches around the world is through the ability to run DC motors to pump water using specially designed highly efficient solar powered water pumps. From the few pair herd small acreage owner or leaser, to the several hundred pair, thousands of acres full time rancher, solar pumps are quickly replacing windmills and electricity as a reliable and economical source for water pumping.
The first solar pumps that we know of started showing up back in the late 1980s and filled a niche for ranchers with shallow wells or who had low grazing numbers needing to water from a deeper well. Some of the early limits these solar pumping systems had were low flow volumes of a gallon to two gallons per minute and maximum pumping depths of 150 feet.
Vast improvements have been made over the years in the solar water pumping industry to both create longer lasting better solar pumps, as well as pumps that can now pump from depths as great as 700 feet at a couple of gallons per minute flow rate and on shallow wells flow as much as 80 gallons per minute. Many of the old style pumps that ran off of photovoltaic power had brush type DC motors, which had problems with the brushes wearing out especially if the proper voltage controls were not used between the solar panels and the motor. Some of the more improved solar water pumps today now incorporate brushless motors, eliminating the need to replace worn brushes as a maintenance item, sometimes eliminating the need for additional voltage controls and greatly increasing pump motor life. System sizes have grown with the depth and flow requirements to anywhere from single panel systems to large multi panel systems and can range from 50 to 1200 watts or more.
Other ways solar power is used on working ranches today is on solar powered fencers to run hot wire for cattle containment. These can also vary from the very low powered fencers to run a small amount of fence to the extremely hot and high powered fencers that can run many miles of electric fence.
Still yet other uses are entrance lighting without having to run 110 AC power to the location and remote barn or shed lighting in which solar panels charge batteries and run either emergency or on demand LED lights for night time use when needed. Some ranchers have even taken the ultimate step with solar power and decided to live completely independent of the power grid and have incorporated complete home solar systems for all of their day to day electrical needs in their homes and offices. With the government giving some healthy incentives towards many of the options listed above and with the price per watt of solar power coming down drastically in the last couple of years, there has never been a better time to put solar to work for you.