Gimbal-mounted Solar Collectors

I design, build and test powerful solar collectors that:

1.  Can be made with home shop tools and erected by hand with no welding or other expensive equipment required;

2.   Harvest high quality energy ( >500^oC, 932^oF, if appropriate) delivering power and heating space/ water for 30 years;

3.  Replace the energy invested in materials within 5 months (cold, northern US);

4.    Primarily use aluminum, glass mirrors and fasteners that are readily recycled or reused with a defective sensor or motor replaced in a few minutes;

5.    Follow the sun all day and turn upside down at night or during storms (hurricanes, hail, snow and freezing rain) so mirrors are clean and frost free when the sun comes out; and

6.    Without subsidies pay for themselves in fewer than five years if owners assemble them and use the energy they harvest, longer if a company installs them with a warranty or if energy during long summer days with good weather is not harvested because there are no appliances that can use it.

The approach my brother and I now work on is based on many years of experience with these point focus solar collectors that track the sun on two axes. The early solar collectors followed the direction of the sun around a vertical axis and moved the mirrors around horizontal axes to accommodate elevation changes. In these, both drives must accommodate changes every minute all day long to follow the sun as it rises until noon and falls until it sets. The current design rotates around an axis that is perpendicular to the axis of the earth and the primary drive must simply power the collector so it makes one revolution a day, or 15 degrees an hour, or a degree every four minutes like the hour hand of a 24 hour clock. The other axis has to accommodate the tilt of the earth, 23.5 degrees, over a year so on many days it doesn’t have to move at all. 

A Computer Model of a 25 Square Meter Gimbal Mounted Solar Collector

Building and operating four generations of this equipment have shown what works well and what needs to be improved. In future posts I’ll describe what aspects are pretty mature and which still need refining. A technical description of the advantages of our approach using a gimbal that rotates around a polar axis (right ascension) with the concentrator/receiver rotating around the declination axis for the seasons is in the patent document: 

www.google.com/patents/US8322332