An improved power free tracking system for box type solar cookers

•A novel method for solar tracking along the azimuth for box type solar cookers.•Proposed mechanism does not require any external power source.•Tracking requirement along elevation is eliminated by an extended booster mirror.•Good solar tracking is achieved for up to six hours.•Experimental results of linear tracking by a prototype have been included. An improved power free solar tracking system for box type solar cookers, suitable for up to six hours of cooking is being reported in this brief note. The requirement for solar tracking along the altitude has been eliminated by orienting a relatively larger booster mirror at a predetermined optimum angle for the day for a particular location. The requirement for tracking along the azimuth has been addressed by using the gravitational potential energy stored in a water container connected to a pair of springs. Discharge of water from the container at a constant predetermined rate drives a timing belt mounted wooden disc to rotate with the sun at a uniform rate. Experimental results indicate that the system faithfully tracks the sun for up to six hours, starting 3h before solar noon and up to 3h after it.