A TRACKING SOLAR CONCENTRATOR
Several pumps are available varying greatly in cost, performance and noise. We have selected a very satisfactory one for the prototype, a Grundfos model UPS20-42 available from heating and plumbing suppliers around the country.
An optional, but recommended safety device that you should consider at this time is a high temperature limit control that will direct the electronic tracking system to get off the sun to prevent a boil-over. We used a Ranco C30-C1250 remote bulb temperature controller with an adjustable range of 120 to 250 F. It has a six foot lead and bulb that can be strapped to the piping at the top of the array while the control is mounted near the hub where you have easy access to it. An alternative is a Honeywell L6008C1206-30 to 270F. Others, who have built copies of our system have elected to install a snap action limit switch, 300F right behind the collector so it can sense an over- heat with no fluid in the system, to transmit heat to the previous device.
Other controls might sense the temperature in a storage tank and direct the array to get off the sun when the desired limit is reached. Any one or all of these controls can be wired into the electronic track- ing system providing they open a circuit when the limit is reached.
