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Dear Pablo: I was wondering what is the most efficient use of solar power? is it small arrays of panels used to heat water, large residential arrays used to power homes, or large solar thermal arrays in the desert?
The answer to this question is a complex "all of the above." The use of solar for hot water and electricity on a residence, as well as the use of utility-scale Concentrating Solar Power (CSP) in the desert, are not mutually exclusive.
So What Is The Most Cost Effective Use Of Solar Energy?By far the most cost effective source of hot water and electricity is conservation, that just needs to be said. Reducing electricity and hot water use through behavioral changes costs nothing, and therefore has an immediate benefit in terms of cost savings and environmental impact. Energy and water efficiency technologies such as energy efficient light bulbs and water-saving shower heads have a relatively low cost and a short payback period.
Hot Water From The SunAfter reducing your hot water and electricity use, the next most cost effective use of solar energy is heating, or pre-heating, domestic water. This relatively simple technology is inexpensive and the savings are immediate, plus you could even do it yourself.
Concentrating Solar PowerFinally, electricity generated from the sun. Large, desert-based CSP plants are very efficient at converting solar energy into heat, and then into electricity. All of this is done without the use of costly photovoltaic (PV) panels, which keeps the facility construction cost down. Line losses during the transmission of desert CSP electricity over long distances does reduce its efficiency, but it is still more efficient that residential PV.
PhotovoltaicPV systems are still expensive but the prices continue to decline and efficiency continues to increase. One benefit of residential PV, besides the benefits to your property value and your eco-hero status in the neighborhood, is that it is distributed. The benefit of distributed generation is that electricity grid is protected from shocks to the system, such as local outages that cascade into regional blackouts, and also avoids the issue of a cloud passing over a large PV installation.Additional Resources On Energy From The Sun:
How Does Solar Energy Work?
New Solar Energy Potential Map Seamlessly Covers All of Western HemisphereBrightSource Energy