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Don't put your money in the sand

image credit: Rich Dzikowski
Rich Dzikowski's picture
CTO DESERTSOLAR UG

Desert.Solar develops innovative and efficient CPV systems especially for desert areas, which offer price and technological advantages over conventional PV.

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  • Mar 19, 2019
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Suppose you're a director of a big bank and a well-known consulting company recommends you to invest the money in solar power plants on the Arabian Peninsula or MENA regions. From an extensive presentation you will learn that there is a real boom in such power plants there and above-average returns are expected from this business. You will be presented with various studies showing that there is more than twice as much solar radiation in this area as in Europe. Because these documents provide ideal conditions for a good business, you will decide to invest, for example, $200 billion in such solar power plants in the next few years.

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In the following you will learn how quickly this apparently good business turns into a mirage, because these excellent business conditions exist only on the paper of the consulting firms.

Everyone who lives in these countries or has visited them at least once knows how dusty this area is. The map below illustrates the dust intensity around the world. The dark blue color with number four indicates countries with the highest dust concentration in the air.

 

 

In addition to the accumulation of dust, there are also tiny particulate matter air pollution PM, which drastically screen the sun's rays already in the air. And all this before the sun's rays have reached the surfaces of any solar power plant. These tiny particles in the air will cause big headaches for all operators of solar power plants from the beginning.

According to this study: “Large Reductions in Solar Energy Production Due to Dust and Particulate Air Pollution” by Mike H. Bergin and other scientists, this blocks approximately 25 percent of solar energy.

As these authors of the above and similar studies have determined, dust accumulation on the surfaces of solar panels causes additional up to 1 percent yield losses daily if these are not cleaned regularly. On average, this is 25-35 percent energy loss within 60 days.

Normally the wind could blow away some of the dust, but it's not. Early in the morning, a few meters from the earth's surface, dew forms, which bonds with the dust and this mixture becomes concrete. This natural process continues all the time and the layers of dust become thicker every day.

If the operators want to avoid yield losses, they are dependent on continuous cleaning of the panel surfaces. This is usually done by hand with water or expensive cleaning robots. A prerequisite for this is that you have to buy water and transport it to the desert areas with cisterns. O&M costs are rising enormously.

In order to save money, some operators have decided to clean the glass surfaces with rotating brushes without water. However, this method has the same effect as treating glass with an electric sand paper grinder. This causes more damage than benefit, because the glass becomes matt and opaque.

Quite frequently, sandstorms are observed in these regions, which completely cover the panel surfaces with sand and this leads to a 100 percent loss of yield of the solar power plants, as the Photovoltaic Institute from Berlin reports on the website. Also a sandstorm can cause 100 percent investment loss by turning solar panels into kites while demolishing the entire power plant.

 

Irrespective of air pollution and dust accumulation on the panel surfaces, there is another decisive factor that causes yield losses in solar power plants. It's heat.

 Anyone who drives a dark or black car knows how quickly it gets hot when it's standing on the open sun. The same happens with solar panels, which are usually dark blue or black. Since their performance is measured according to standard test conditions, which assume a module temperature of 25 °C, with every additional degree up to 0.45 percent performance is lost. At a panel temperature of 60-80 °C, which is conceivable in the desert, the energy loss would be 20-25 percent. All mono- or polysilicon semiconductor solar cells currently in use have these unfavorable properties.

While in Europe photovoltaic modules only have to be cleaned every two years due to frequent rainfalls, in the MENA region they have to be cleaned at least twelve times a year to avoid excessive yield losses. This factor would also cause considerable O&M costs.

If we add all the above-mentioned circumstances and energy losses together, it becomes clear that these are by no means ideal conditions for the construction of a solar power plant in the desert regions, because nature is constantly taking its toll and this will not change in the coming years. If you have too much capital and want to get rid of part of it, don't bother with such investments, but give the money away immediately for charitable purposes. This will at least save you worries about watching it sink into the sand.

In order for the obvious energy surplus from the sun-rich countries to be used at all, novel solutions must be developed that are able to cope with the desert regions. The existing technologies have no place there, because they cause too many losses.

Fortunately, there are solutions specifically designed for desert conditions. One of them is a solar power plant, which is protected against the aforementioned disadvantages and supplies electricity around the clock. Thanks to a clever automatic cleaning system, there is a full energy yield every day, while O&M costs remain minimal. www.desert.solar

This innovative solar power plant uses free solar radiation as well as free air, which is converted into kinetic energy by compression. Instead of the precious water, the sand and dust particles are blown away from the collector surfaces with compressed air. This cleaning process is carried out automatically several times a day and also at night.

This results in two immediate advantages:

- In contrast to water, the air is available everywhere for free and does not need to be transported over long distances.

- With the kinetic energy from the compressed air, the collector surfaces will remain constantly clean.

Because the collectors are located more than 6 meters above the earth's surface, there is no dew that can transform the dust particles into concrete. The area below can thus be greened and used as a meadow for farm animals.

 

 

With this system the sun is concentrated about 1000 times, there are no problems with the heat. The ADAM modules generate both electricity and thermal energy. Similar to combustion engines, the thermal energy is dissipated from a closed circuit with a liquid.

Since this system uses the power not only of one but of several hundred suns, the CAPEX is limited to half of the usual photovoltaic systems. 

 

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Matt Chester's picture
Matt Chester on Mar 19, 2019

It's interesting looking at this with another story on Energy Central today about how snow can affect solar panels in quite a different climate: https://www.energycentral.com/c/pip/fact-check-snow-solar-panels-problem...

The conclusion of both seems to be that the issues are overcomable, and in fact the solutions of the future are likely to be shared among these use cases

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