Solar PV – Energy Payback

More often than not I get asked about financial payback periods for grid-connect photovoltaic (PV) solar systems, but recently a couple of people have raised the question about the energy payback period of solar PV. One of the suggestions put to me was that solar panels don’t generate enough electricity in their lifetime to offset the energy that was taken to produce them in the first place. This is a bit of a myth and totally incorrect of course, but it’s a point I’d like to clear up.

Most crystalline solar panels have an energy payback time of 1-2 years. This information normally isn’t too difficult to find by looking either on the solar panel datasheet or the manufacturer’s website. Norwegian company, industry leader and one of Green Energy Options’ preferred providers is REC solar. REC have managed to get their energy payback down to one year, with some thin-film panel manufacturers pushing it even lower. It’s also worth noting that through innovation and technology, we will probably see efficiency improvements in both the panels and manufacturing plants leading to even lower embodied energy in solar panels.

Conergy Solar panels

Conergy PH190W Monocrystaline solar modules

That’s fine, but there are a number of other components in a solar power system, the inverter, aluminium mounting hardware, cabling and other balance of system components. What about the energy taken to manufacture these? Good question, here’s where things start to get tricky. Where do you find out how much electricity was used to manufacture an aluminium mounting rail? What about the petrol burned to get it from the factory to the wholesaler to the installer to site? Complicated hey, particularly when each solar installation is different in many ways. The amount of sunlight at a location, orientation and pitch of the solar array, the distance from manufacturer and mounting type are just a few of these variables.

Trying to do these calculations myself looked a little time consuming, so I’ve found a couple of good reference articles that can fill you in on the details, note the Renew magazine article is probably the most recent and relevant to Australia.

Renew Article 109 by Andrew Moore

http://www.renewableenergyworld.com/rea/blog/post/2011/07/studies-show-pv-panels-return-embodied-energy-in-1-3-years

http://www.ecotopia.com/apollo2/pvepbtoz.htm

http://spectrum.ieee.org/green-tech/solar/how-free-is-solar-energy

The short story is that the whole system energy payback sits around two years, depending on your location and other variables, with the majority of the embodied energy in the solar panel manufacture itself. Note that one of the things that we at Green Energy Options try to emphasise to people is that it is important to buy good quality components, like anything else, you get what you pay for and a solar system that breaks down due to faulty components will mean your payback period both from a financial and an embodied energy point of view goes out the window. Hopefully that clears things up, now you can rest easy to know that the solar system is a good decision for the environment as well as your back pocket.