Most existing solar technologies, of all types, are either high-tech-high-power (usually designed to produce electricity for the “rich” countries) or very low-tech-low-power (usually designed for basic survival in the “poor countries”).
Sophisticated, expensive technologies are not accessible to most people living in the tropical Sunbelt, who can most benefit from solar energy. The very simple low-power technologies are valuable for many uses – to heat water for instance – but they are too limited in scope to provide energy independence in themselves: frying, baking, steam and small local industries generally require more heat and more power. All these super-sophisticated and super-simple technologies can be very useful in specific situations for specific needs, both rich and poor countries, but by themselves they cannot displace a majority of fossil fuel and biomass burning in the world.
It is possible however to create high-power solar technology while remaining low-tech and accessible. As far as we know, only two technologies have made significant advances in this area. Solar Fire, described above, and the Scheffler Reflector. Over 2000 Scheffler reflectors have been built in India.
Both the Scheffler Reflector and Solar Fire have proven themselves possible to build with locally available materials. Both use the principle of a fixed focal point, which greatly simplifies constructing and using an application – a moving focal point can be more efficient but poses a lot of practical problems.
The main advantages of the Scheffler Reflector is that it can follow the sun on a single axis, powered by a simple gravity clock, that it can be built from common materials and of course that it provides free energy access once built. The main disadvantages are that many of the structural pieces must be very precisely bent and the machine installed parallel to the earths polar axis, so due to the precision necessary it is not easy to build or install a Scheffler Reflector without prior training (though it is of course possible, without a science or engineering background the concepts involved are not obvious).
The advantage of Solar Fire is the whole structure is made of straight lengths and it relatively easy to build and install with only general construction experience and no special training. The main disadvantage is that the tracking is on 2 axis and cannot be automated so simply, though currently the “effort” in tracking the machine manually is significantly less than maintaining a biomass or coal fire.
All solar technologies give access to solar energy, which is free, so “which technology is better” of course depends on the situation and the particular need. All solar technologies, and renewable energy in general, are complementary when used in the right place for the right use.
Eerik and Eva Wissenz (Jan 2011)