Here’s a DIY soalr tracker, turned people’s choice for Australia’s “New Inventors” show -
It is a new type of ‘passive’ solar tracker that uses a combination of direct sunlight (radiant heat) and shade (ambient air temp) to affect the thermal expansion and contraction of a liquid to make the solar panel rotate. The expansion of the liquid causes the panel to rotate toward the west during the day and the contraction causes the panel to rotate back towards the east at night, ready for the morning sunrise. The simple hydraulic system, ensures that the solar panel is angled towards the sun from dawn through to dusk – all year round.
Solar projects @ MAKE – Link.