Solar Technology and Cost
Solar power technology has been around in some form or another for thousands of years. Even many modern solar device designs are now decades old. Yet, they have not fulfilled the promise that many hoped. Why? Two reasons: efficiency and cost.
Of the approximately 1,000 watts per square meter of sunlight power falling on the surface of the Earth (at the equator), only a small portion can get converted into usable electricity. Part of that loss is because of internal losses. Of the photons that hit a solar panel, only some will knock loose an electron. Of those, only some will travel down the module and into the device before being recaptured.
The latter effect is an issue called carrier lifetime. The longer the electrons wander around loose, the more likely they are to flow out of the module and down wires to an outlet. Most modules can only achieve in the neighborhood of about 10-15% efficiency. But several companies have raised the efficiency of their devices to as high as 20% by extending that carrier lifetime.
By contrast, solar thermal devices use sunlight-heated salt water panels to generate steam that can be turned into electricity. The efficiency is often as high as 30%. But not only are such devices expensive, they are high risk. The high temperature and pressure of the water can do considerable damage if it escapes.
Apart from efficiency considerations, costs remain relatively high.
Most types of solar panel remain fairly expensive. A 30-watt module costs in the neighborhood of $250, while a 195-watt panel will run almost $1000. In order to install a solar panel power system for a modest home will require panels costing somewhere around $10,000-$16,000. Add batteries and other components and the cost is anywhere from double that to triple or more.
Fortunately, as oil and natural gas prices continue to rise, manufacturers have responded. As the market matures for solar technology, research dollars have been spent to come up with new ways of increasing efficiency and lowering costs. Even with the relatively high price of large application panels, the cost is still much lower than it used to be, accounting for inflation.
The cost of PV (photovoltaic) cells has been falling by about 15% per year for the past 10 years. Given that they can easily last 20 years, they can pay back the initial investment, while providing clean power.
And improvements continue. A major European chip maker, ST Microelectronics, now has prototype solar cells that are expected to be considerably cheaper than today’s panels.
Organic compound solar panels are making their way into certain applications like computer keyboards and monitors. Those flexible plastics allow a computer to be folded up or rolled like a magazine. While still expensive, the costs are coming down as the technology matures. A French-Italian company expects to produce an organic cell soon that it estimates will produce electricity at around 20 cents per watt, compared with about $4-$8 per watt for ordinary solar power.
Water heating by solar power has costs that vary, too.
In the 1920s some municipalities used large storage tanks to solar heat and store hot water that was then supplied to homes. As the price of electricity and oil came down, which were used to heat water, they were no longer cost-effective.
But as things progress, those old ideas are becoming new again. Such methods may well soon be competitive again, if current research bears fruit. With the price of oil and electricity from gas and coal-fired plants continuing on the trend of the past 10 years, it would only take a small improvement for new applications to be economic.
