Abstract: An open loop servo controller for controlling motors which drive a solar energy utilizing device about its azimuth and altitude axis to track the sun. The controller has a central processor and elements for inputting data corresponding with the present day of the year, the hour of the day, the minute of the hour and with the latitude and longitude of the device installation. Memories store program data, and tables of data corresponding with the declination of the sun on any day and of other mathematical functions. The processor uses the data to calculate the azimuth and altitude angles of the sun itself within every minute of the day and causes signals to be produced which result in motor controllers causing the motors to turn the device through azimuth and altitude axes angles corresponding with the calculated angles.

Abstract: A plural stage solar radiation fluid heater comprises a housing having a top in which there is an array of lenses. Near the inside bottom of the housing, there is a first fluid conduit located at the foci of the lenses for absorbing primary solar radiation focused thereon. One or more additional conduits are interposed between the first conduit means and the lenses and are arranged to permit passage of the ray bundles from the lenses to the first conduit means. The arrangement is such that the intervening circuit means intercept secondary terminal radiation which is re-radiated from the next adjacent hotter conduit means.