The client who was a researcher asked for a proof of concept design for making a special type of tracker. The tracker was working based on the solar thermoelectric power generation principle. According to the request by the client an SP1848-27145 thermoelectric power generation tablet was to be used in the final design. These tablets were supposed to be arranged in a rectangular shape and based on the generated voltage, they were supposed to distinguish the azimuthal and zenithal angles of the sun and so driving a two-axis tracking system towards the location. The truth table and the pattern based on which the design was to be made was as follows
1. The system was a proof of concept design and a non-conventional tracker that was basically aimed at a research purpose and therefore had to be carefully designed.
2. Since it was a new work, the design had to be carefully made for a successful result
3. The main challenge was getting the right configuration that could properly tune tracker’s movement according to the thermal intensity of Sunbeams on each of the sensors and align the PV panels towards the right direction.
4. The design was to be made in a such a way that the motors could properly direct the panel towards the point of the solar beam based on the voltages produced by each of the SP1848-27145 thermoelectric power generation tablets.
Description of the work:
Before starting the work, the thermoelectric properties of the SP1848-27145 was found to be as below:
• Lead Length: about 30cm
• L x W x H: 40mm x 40mm x 3.4mm
• Temperature difference of 20 degrees: open circuit voltage 0.97V, power current: 225MA
• Temperature difference of 40 degrees: open circuit voltage 1.8V, power current: 368MA
• Temperature difference of 60 degrees: open circuit voltage 2.4V, power current: 469MA
• Temperature difference of 80 degrees: open circuit voltage 3.6V, power current: 558MA
• Temperature difference of 100 degrees: open circuit voltage 4.8V, power current: 669MA
In order to rotate the solar PV panels two Gear Motors 17-228 were used. This Gear Motor is designed for low-voltage power-efficiency, but it isn’t scared of generating a bit of torque, and the output shaft is shaped just like the GM2/3/8/9 for full accessory compatibility!
It’s a small, slow, power-efficient but torquey motor, weighing in at only 35.7g (1.26oz)! It’s a bit bigger than its more powerful brethren, measuring in at 51.7mm (2.04″) long, 27.3mm (1.07″) wide, and 32.1mm deep (1.26″) excluding shaft. This High-Efficiency (HE) 3V DC motor coupled to a 228:1 gearbox gives a very useful low-power gearmotor.
Basic stats of this motor was given as below
The below image describes how the tracking mechanism worked
The design was made using two different methods to find the most efficient method
– Using logical gates
– Using opamps
Based on the software simulation of both designs, they were both prototyped and checked
Solution and Impacts:
The whole project including its prototyping took about 6 weeks to get completed. During this short period, both designs were developed, prototyped and delivered to the client.
The final tests on both designs were in complete agreement with the requested design.
While the design was at its elementary steps; however the results of the tests proved that this innovative tracker could be developed to a level comparable or even higher than the existing trackers working with sunbeam intensity.