Hey I am Bassem Student in faculty of engineering i am really interested in Thermo electric units , i am worked in a project which need to produce volt & current from its heat i found your site & fan page on facebook , i want to know which category or model of your TEG Products will be usefull for me as i want to produce min 6 V and 0.5 Ampere from Delta T min 20 C and Max 50 C how many of thermo units should i use and how can i connect them in parallel or in series or both to get the 6 V &0.5 Amp ?? please answer very fast to order the products from you and get it as soon as possible , Thanks
This second link shows a 40 mm X 40 mm device producing 0.66 watts for temperature differential of 50 deg C. The available power appears to be roughly proportional to the square of the temperature differential. Using this, a 20 deg differential might produce 0.1 watts.
For the 3 watts at 20 degrees you want, at least 30 of these modules are needed. A MPPT (Maximum Power Point Tracking) controller could be used to maximize power output while providing regulated 6 volts.
This page at Linear Technology explains MPPT and shows several circuits.