SOLAR POWER (Part 2)
This photograph shows part of the photovoltaic solar array at Nellis Air Force Base in Nevada, the largest solar array in the US. It occupies 140 acres and has 70,000 panels. It was constructed by the SunPower Corporation, and produces a maximum rated 14 MW which is approximately 25 % of the power requirements for Nellis AFB.
Click on the photo for a larger image in a new window.
This photograph was taken by Senior Airman Larry E Reid Jr. as part of his official duties and is in the public domain.
Before we actually start with this I would like to point out that the cost of producing electricity using Solar energy is four to five times that of conventional coal. There are people who still scoff at this even after it has been explained to them because the perception is that sunlight is free, and because of that so should any power generated by using the light and heat of the Sun.
To offer a point of comparison, I’d like again to explain the cost of a large 2000MW baseload nuclear power plant. After planning and approvals, the day one cost as the first sod is turned might be around four and a half billion dollars, but the plant does not produce power for at least seven years, so at the going interest rate for the loan, the cost escalates by a further 225 million a year, hence by the time it comes on line feeding power into the grid and actually earning money, that original cost has blown out to almost six and a half billion dollars, so the expense is not due to the plant itself but because of the cost of money.
The same applies for solar power. There is a huge up front cost, again exacerbated by the cost of money.
So, the complexity and vagaries of each method of producing electrical power differ in ways not actually related to the process itself.
So even though you can lay on the beach, and be warmed (and even burned) by the Sun for no cost, it is entirely different when it comes to producing power from that same warming Sun.
Photovoltaic Solar Power.
I mentioned in the previous post about the solar panels on the roof of a house. This is the photovoltaic method of power production.
The light of the Sun shines on small cells. The cells are made typically of Silicon because of the number of free electrons in that atoms outer shell. The light makes those electrons move around faster thus generating electricity, and believe me, this is the simplified version for ease of understanding. Selenium is also used, as is Boron and Phosphorous. The atoms of each of these elements share electrons thus generating the electrical power. Small plates made from each of the elements are sandwiched together, with minute electrical wiring connections joining the plates. Hundreds and sometimes thousands of these cells are then connected together to form solar panels. The panels are encased to hold them together and covered with toughened glass on the front. When you look at the photograph of the house with the panels on the roof, you’ll see there are thirty of those panels typically sized approximately six feet by four feet.
Now you have some idea of the cost, taken up completely in the intricacy of their construction, and the time it takes to complete that construction and the materials involved and their conversion into the cells and then the panels.
That large household version in the photograph costs around $45,000 or so. It might supply your household power, but when the Sun goes down, the house needs to draw its electricity from the grid, as there is no way to store the Solar power generated in this manner.
The advantage of a large system like this is that during the day while the family is away at work and school and the Sun is shining, the generated power is being fed back into the grid, and as incentive, Governments offer attractive rebates for this, sometimes three times the cost BACK TO you as a consumer.
So, you use power during the day, some is fed to the grid, and you use power from the grid at night. Typical savings might amount to half your power bill, and with the rebate, that again takes some off the total. Assuming that you’re saving half, and getting the rebate, then the return might be as high as 80% of your yearly power bill. A typical household bill here in Australia might be $2500 per annum, averaged. I know that you in the US have typically higher charges for your power. The savings for that Australian family might be in the vicinity of $2000 per year. So, to recover the cost of the System $45,000, you’ll need to live at that house for 20 or so years, because you can’t take it with you if you move house.
Selling the house might attract a higher price because it has the system, but there is conjecture on that point, even though the system might make up as much as 10% of the cost of the house and land for the seller, but if he actually achieves the return for the system, it is again a matter unrelated to environmental concerns.
On the larger scale, you see the huge initial outlay for the panels, the infrastructure just to connect all those panels, together, to have them articulated so they track with the Sun for best effect. By their nature, they are exposed to the elements, hence rain and dust. If it rains then dust adheres to the glass. The glass covered panels have to be perfectly clean to operate at their optimum, so someone has to constantly clean the panels, sometimes up to 70,000 for a large array, adding to the ongoing cost for the manhours element. The power generated is DC so it all has to converted to AC for feeding into the grid, hence large inverters are needed with step up transformers as well.
Now you can see the cost mounting.
The huge initial outlay, and the resultant cost of money, the cost of the vast infrastructure, the ongoing costs now all add up, making solar power one of the most expensive forms of production.
However the big thing that scares owners of these power stations is that as soon as a cloud just scuds across the face of the Sun, production goes down by as much as 25 % immediately, and then takes time to build back up, so on cloudy days, power is minimal, and now you can see why this form of photovoltaic power cannot be used as constant, reliable set level baseload power.
This photograph is of part of the array at the Serpa Power Station in Portugal. It totals 52,000panel modules, and covers a hillside over an area of 150 acres. The panels were constructed by SunPower, Sanyo and Sharp, and track to follow the Sun. It produces a maximum of 11MW.
Click on the photo for a larger image in a new window.
This photograph was taken by Aurelio A Heckert and is a commons photograph in the public domain.
Having taken all those factors into account, there are still large power stations using this photovoltaic principle.
The US is the third largest user of this type of power on the Planet, so it’s not like the US is addicted to coal. There really are engineers out there doing this sort of work.
Germany and Japan lead the World in use of this form of power, and Spain is also a large user.
There are advances in this form of power production concentrating the voltage to heat oil which boils water to steam to drive a turbine.
In Australia, construction is underway to bring on line the largest photovoltaic power plant on Earth. It will produce a maximum of 154 MW and will supply up to 50,000 homes. It combines the solar panels in arrays, but uses heliostats also, tracking mirrors that follow the path of the Sun, and designed so that they concentrate light onto the panels vastly increasing power production from each panel. The cost is close to $450 million for a relatively small 154 MW maximum. (degraded because of the nature of its variability)
As more solar panels are constructed and then be used for arrays, the cost will become cheaper, but because of the variability of the light, then this form of power generation can really only make up a minor fraction of the overall pie chart, and if renewables can only make up 20% at best, then the Solar part of that shrinks somewhat.
If you follow some of the links, you’ll see from the maps that solar power might only be economically viable in that Sun belt, and in Southern States of the US and most probably those in the South West.
The problem however will always be the high cost of the manufacture of the panels, the infrastructure needed to connect them all, and the fact that the Sun sets every night for almost half the time that power is needed..
So, when environmentalists point to this as the way of the future, it will only ever be a small part of the solution.
The next post will detail the third part of the solar equation, that of Solar Thermal, which might be the most promising aspect of the whole Solar story.