It is commonly believed that a major problem with solar panels is that they consume such a significant amount of energy in their manufacture that the energy they produce is negligible in comparison. So how much energy does it take to make a solar panel and is it still worth it considering how much energy they can be expected to produce?
According to a study in 2000 by Knapp and Jester, it takes around 5600kWh per kWp in the manufacture of monocrystalline panels. It must be considered however that this figure may vary according to the scale of production, larger batch sizes resulting in greater efficiency. This is divided roughly in half between material production and processing. While energy expenditure in such things as labour and transportation were not included in calculations it was concluded that these were relatively insignificant.
Considering that in Sussex solar panels can be expected to produce 900kWh per kWp in a year then in just over 6 years the panels will have produced the same amount of energy as it took to make them. Monocrystalline panels have a minimum life expectancy of 20 years and can last for over 50. If we then assume an average life of 35 years we will have the result that solar panels will in fact produce around five times the energy it takes to make them.
Sources
http://solarbus.org/documents/pvpayback.pdf
http://www.energyfits.co.uk/solar-pv-feed-in-tariff-calculator.html#anchor
http://www.solarpowerfast.com/build-solar-panel/monocrystalline-solar-panels/