Dealing with the dilemma of wanting to install power-generating solar panels, but these are too bulky and will leave no space for your solar heating system? Worry no more. Researchers have developed an integrated PVT using amorphous silicon that optimizes the efficiency of both solar electricity generation and solar heat generation in one convenient package.
Conventional solar photovoltaic thermal energy systems or PVTs can theoretically generate both electricity and heat. However, in reality, these are not efficient heat-generating systems since a low temperature is needed to cool crystalline silicon solar cells in order to generate optimal current.
It is better to use separate power-generating solar panels for electricity generation and solar thermal systems for heat generation. The problem is that solar panels are very bulky and will leave no space for solar thermal systems.
Joshua Pearce, an associate professor in Michigan Technological University, had recently published two studies describing the use of a more efficient PVT using amorphous silicon. His research associates are Kunal Girotra from ThinSilicon, and Michael Pathak and Stephen Harrison from Queen’s University.
Solar panels are usually made up of crystalline silicon. However, amorphous or thin-film silicon can also be used. Amorphous silicon is lighter, more flexible and cheaper. It also has a greener footprint since it requires less silicon. The problem is that it generates less current and it suffers from the Staebler-Wronski effect.
Pearce explained that this effect occurs when the efficiency drops due to exposure to light. This is a great disadvantage for a solar cell. However, he and his team worked around this difficulty by incorporating thin-film silicon in a new type of PVT.
Thin-film silicon does not have to be cooled, unlike crystalline silicon, to make it work. Pearce and his team discovered that heating it to solar-thermal operating temperatures, which is near the boiling point of water, allows them to make thicker cells that can overcome the Staebler-Wronski effect.
They also discovered that when thin-film silicon is applied directly to a solar thermal energy collector, the solar cell’s electrical efficiency could be increased over 10 percent by baking the cell once a day (or spike annealing).
Pearce said their new and improved design is more efficient in optimizing both the thermal and electrical generating capabilities of PVTs. He predicts that in 20 years every rooftop will be made of integrated PVT since this gives the most usable solar energy per square foot of roof space.