By May 9th, we'd had three fabulous sunny days in a row and the pool temperature was up to almost 70 degrees F (starting from about 55).
Since then, the weather has turned cold and rainy and there is no sun until next Tuesday according to the current forecast. Almost two weeks without sun.
I've diverted to other projects temporarily.
Here is the current setup of six collectors waiting for the sun to shine again.
The current drive system (click on any image to enlarge it) consists of a motor driven screw which carries a traveller connected by push rod to the end of the metal shaft connecting the reflector arms.
The tracking sensors and drive electronics are not yet installed. The reflectors are moved manually by connecting a battery to the motor wires as long as it takes to move the reflectors toward the sun.
Here is another view of the drive mechanism. The springs at each collector arm help to absorb buffeting from the wind.
While the heat collector tubes are metal and opaque to light, I will add a glass tube at the focus of one or more of the collectors to allow the intensely focussed sunlight to travel through the water. While the heat absorption may not be as good as the black coated metal collector tubes, since the sunlight is concentrated about 20 times, I expect that the concentrated UV rays will sterilize microorganisms in the water.
I've pressure tested the seals of the one glass collector tube which I've assembled, shown here waiting for installation.