Solving Africa’s Energy Poverty – Part 3 Solar Power

Why SOLAR Power is a poor choice for developing countries

The main practical problem with solar panels is that they produce power intermittently and variably depending on the latitude, the time of day, the season, and weather events such as clouds, rain, and windblown dust that block sunlight. Another factor that affects output of solar panels is heat, which further reduces output and lifetime. That is why most rooftop solar panels are mounted on supports above the roof surface. In hotter climates, it may be necessary to provide cooling water to maintain efficiency, all of which reduces photovoltaic efficacy. They do not provide power at night and so there must be a reliable backup power source such as banks of batteries. Present battery technology is not feasible for this purpose except for single home systems, so thermal and hydroelectric energy must be used.

Solar panels are inefficient by their nature. Single junction panels are based on high-tech silicon wafers and the more efficient multi junction types require silicon wafers layered with exotic metals such as gallium, indium, phosphorus, gallium arsenide, and germanium to broaden their power spectrum and enhance output. The sun provides roughly 1 kW power per square meter at vertical and solar panels or mirrors provide only a fraction of that. Typical efficiency of solar photovoltaic cells is from typically 15 percent up to a possible 30 percent.

Peak output occurs only when the panel is pointed directly at the sun so computer-driven tracking mechanisms would be needed to maintain peak power throughout each day. At higher latitudes, the sun is never directly overhead, so the sun would be at an angle from the vertical and power would be reduced by the greater depth of the atmosphere even with compensating angled support. This varies with season by up to 23.5 degrees above and below the equatorial plane because of the tilt of the earth’s axis. So in winter, the angle could be 47 degrees or more from vertical, depending on the latitude. Even near the equator, only near the equinox will the sun be directly overhead at noon and could be as much as 23.5 from the vertical. Many solar arrays use fixed panels so that they operate outside peak performance most of the time.

All of these factors will reduce average output considerably. Maintenance teams are needed to maintain the tracking mechanisms and water cooling circulation systems, as well as for regular cleaning of the panels.

The next hurdle is the lifetime of the solar panel. Efficiency decreases with age and typical solar panels will last only twenty years with typically 1 percent loss in efficiency per year. Then you have to factor in how much energy is expended in manufacturing, installing, and maintaining units. This can be a significant percentage of the typical output over time. It will usually take about a year to recoup the energy balance. With short lifetimes, high-tech materials, low efficiency, intermittency, and maintenance requirements, it is clear that solar power through photovoltaic panels is totally unsustainable. Never mind that the power source, the sun, provides renewable power, the panel itself makes this method totally unsustainable.

Ivanpah mirror array in California, Washington Times

Solar power using mirrors is a bit more reliable since it eliminates exotic materials and high-tech manufacturing. However, it has most of the same limitations as Photovoltaic (PV) solar panels. These limitations include no night power production as well as weather, and latitude reductions in efficiency. Some now use molten salt as a heat reservoir to supply supplemental power at night. Maintenance teams are needed to keep the mirrors free from dust. A major problem with mirror systems is that many mirrors must surround and be aimed at a central steam generator to produce the kind of heat needed to produce the steam for a turbine. The heat from these systems can kill birds in flight, and the glare can blind airline pilots.

Both types of solar arrays require a large expanse of land to produce a reasonable amount of power. This necessarily disrupts the environment. Rooftops of warehouses, where available, can be used for PV panels, but the mirror arrays cannot because they must be aimed at a central tower containing a generator at the top. Fires on rooftop PV arrays are all too common from breakthrough shorts and wiring issues.

Solar Panel on thatched roof hut

From this, it seems all too obvious that solar power is inadequate even for home use in poor countries and can only be a temporary “Band-Aid” to assuage the consciences for feel-good well-heeled environmentalists in Western countries. Climate agreements envision solar panels on huts, not reliable, long term power as provided by fossil fuel, hydroelectric, geothermal or nuclear power grids. International organizations invest only in wind and solar while discouraging or prohibiting these more reliable power sources that could support infrastructure development, industrial investment, hospitals, schools, provide jobs that can raise the economy and improve health and longevity.

 

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