Mythology stories made such an interesting reading. Greek mythology, Hindu mythology, Chinese mythology…. Virtually every civilization had a library’s worth of mythology. Today, people are supposed to be much more scientific, and realistic. But mythology exists even today and that too about current issues. One such myth is about the energy foot print of solar panels. That the fabrication of a solar panel takes in more energy than the panel will ever produce! Is it a myth or a truth? Myth or truth, it is a very disturbing question. Are we producing ‘clean’ energy by putting in more ‘dark’ energy?
Years back it may have been a truth. However, today it is a myth, proved as a result of thorough scientific analyses. How does the construction of a panel consume energy? From sand to PV panel there are a number of processes. Certainly, All these processes consume energy and that is the reason for the myth.
However, the figures have been checked and the myth busted. Erik Alsema, a researcher at the Utrecht University has made calculations. He has estimated that energy required for construction of (frameless) mono-Si panels was (in 2010) 600 KWh / m2 and for poly-Si it was 420 KWh/m2. Then he made a very reasonable assumption that the efficiency of either type was 12 percent. With such a panel installed he calculated the energy payback period to be nearly four years for the multi-Si frameless panel. He also estimated that ten years hence, with efficiencies increased reasonably, the energy payback period would reduce to about two years.
He also made calculations for the thin film Si panels (with frame). As a result, with 120 KWh /m2 for the panel, an equal amount for the frame and rooftop structure, and 6 percent efficiency, he estimated the energy payback period to be about three years.
These figures are now widely accepted, and quoted by the literature present at the US NREL website. It is also to be noted that the light conditions were for Europe. Nearer equator, with much more abundant sunlight, one can expect even shorter payback periods.
Now think! A panel is normally warrantied for 25 years, but will last over 30 years. How many times over will the panels of today pack back the energy invested in them?