Fairfax Tech Talk Column

Fairfax Tech Talk Column

11.9.2020 The Holy Grail of solar panels - Tech Talk Column 215


In raising our four children, my wife and I hope we have managed to achieve many things but, at the very least, we hope we have taught them to have a sprinkling of scepticism about the world around them. When something seems just way too good to be true then, well, there is a pretty good chance that it is. You know the type of thing…the five million pound lottery win for a draw you didn’t enter; the windfall from the massive estate from the overseas deceased unknown relative and those claims of receiving something for nothing – like free energy from the sun.

Hold on. That last one might actually have something in it.

Since 1953 SW Hart and Co. (later Solahart) has been promising to give you hot water free from the sun. Moving from hot water to electricity presented different challenges and although the photovoltaic effect was first discovered in 1839, it took until 1954 just to reach 4 per cent efficiency. Efficiency has now improved to the point that a new record was set five months ago at 47.1 per cent but the efficiency of most solar panels installed on rooftops around Australia is in the low to mid twenty per cent range.

Last decade saw the start of a dramatic increase in the total amount of power generated by rooftop power. A combination of more efficient panels and a drop in the cost of the panels was helped along with some generous feed-in tariffs. The result? 11.8GW of power is currently being produced by rooftop power. We are still only scratching the surface though. A recent report had the total potential rooftop power output for Australia at 179GW (enough for our total electricity needs) but that would mean every vaguely horizontal surface on every building would be covered with solar panels. It probably isn’t going to happen.

The most exciting current development is with solar glass. The major challenge for scientists is to maximise the ability for the glass to produce power whilst not compromising transparency. A new record was recently set by University of Michigan researchers where they achieved 8.1 per cent efficiency with the generation of power and 43.3 per cent transparency. Even though the solar generation seems low compared to the panels we have on our rooftops, the huge advantage with solar glass is in surface area. Take the example of the Willis Tower in Chicago. At approximately 70m by 70m at the base and a height of 442m, the absolute maximum roof space would only be just under 5,000 square metres but just the surface area of one face would be almost 31,000 square metres. Even if the glass was only one third as efficient as solar panels, the surface area being six times greater would give you a better generation of electricity. More importantly, the electricity is being generated where it is being used. Could we even dream of a skyscraper with enough solar glass that it would be energy positive? It comes with another positive. I remember standing on the balcony of the Mandalay Bay in Las Vegas marvelling at the almost mirror like surface of the entire building. I was told by locals that, with temperatures as high as 47 degrees Celsius, the mirrors were designed to reduce the amount of heat entering the building. Solar glass limits the heat but also generates electricity. I think we are seeing the next step forward in materials used for skyscrapers.

Tell me what year you think Australia will produce more than 50 per cent of its power by renewables at ask@techtalk.digital.

Mathew Dickerson