Experimental study on the performance of solar thermoelectric generator / Raihan Abu Bakar

An increasing demand on energy over years as well as the CO2 emission of fossil fuels
have led toward exploration on alternative energy sources mainly renewable energy.
Solar, one of renewable energy sources, has proven to be beneficial as it is not only
pollution-free, but can also be used to produce electricity and thermal energy. Two main
solar technologies are used to harness the solar energy namely Solar Photovoltaic (PV)
and Solar Thermal system. The former converts solar energy to electricity whereas the
latter produces useful thermal energy from the solar energy. Nevertheless, solar thermal
collector can also be combined with a heat-to-electricity-direct-conversion technology
called Thermoelectric Generator (TEG) to produce both electrical and thermal energy.
The combination of these two technologies is known as Solar Thermoelectric Generator
(STEG). The advantage of STEG is not only it can produce two different outputs, but
also harness low grade heat such as solar energy by converting directly into electricity
without the need of installing the moving parts or components. The absence of moving
parts on power generation shows TEG is a maintenance-free and noise-free technology.
Despite having the great advantages as mentioned earlier, STEG has also its drawbacks.
Low power output has always been a major obstacle for this technology to become
mature. Therefore, this research aims to evaluate STEG performance under different
operating parameters as well as investigating the impact of different TEG array
configuration. The impacts of operating parameters which are water flowrate and tilt
angle and two TEG array configurations (TEG Series and TEG Parallel) were evaluated
through an outdoor experimental work. Prior to this, a theoretical model was developed
to predict and compare STEG performance with experimental result. The comparison
of maximum power output resulted in a good correlation between the theoretical and
the experimental data. A maximum deviation obtained is 19%. From the findings, STEG
produced the highest electrical output with the highest water flowrate. With a maximum
water flowrate of 33 ml/s, the average open-circuit voltage recorded is 518 mV. As for
tilt angle, STEG electrical output increased from 100 mV/day to 401 mV/day when tilt
angle increased from 3°to 20°. However, STEG electrical output decreased from 401
mV/day to 300 mV/day when tilt angle increased from 20° to 30°. This study shows the
tilt angle plays a significant impact on the STEG performance. In term of TEG array
configuration, TEG Series always produced higher power output than TEG Parallel.