I have yet to decide who I will have do my geothermal heat pump system. I will be doing a mat/loop system in my pond. This involves trenching to the pond and spreading the pipe on the bottom of the pond. The pipe is then covered with dirt because it floats. I cannot do the typical pond installation where a coil of pipe is weighted and sunk. This is because my pond stands a very good chance of filling with sediment over the years. The pond coil installations require contact with the water for heat dissipation. If the sediment over, they cannot dissipate the heat and your system will not work properly. I cannot use a ground water source system because the water table is too deep.

As far as loop system costs, the most expensive are the vertical wells. Each well costs about $5K and a typical house needs 3 (or so I have been told). Next least expensive is the ground coil system where large trenches are dug and the coils buried. I have been told that this is a poor choice in clay soil as the clay can pull away from the coils, reducing contact area and reducing system efficiency. The next least expensive option is the mat/loop system in the bottom of a pond that has not yet filled with water. And the least expensive option is the pond coil system, but, this should only be used in a pond that will not gather much sediment.

Hi All

This post comes to you from South Africa.

I have just read of a major technological breakthrough in the area of light conversion into electricity.

The development is said to be as significant as the introduction of cellular phones and bears no resemblance to exiting solar technology at all?

After 12 years of research a local, Professor Vivian Alberts, has developed and patented the panels.

30sqm of panels costing under US$5000 will generate 3kw of power per day, even in overcast, winter and rainy conditions. The life span of the panels are 25 years.

The patent apparently has been sold to a German company for US$500mil and they will take the marketing and manufacturing further.

Should there be any interest I will try to find a web address as my wife also earns her keep at the same university.

Regards - Dennis
Johannesburg

http://cooltech.iafrica.com/features/508857.htm