One of the most persistent prejudices against photovoltaics is the claim that the expense and effort of building a solar system is greater than the yield you get in return. Various environmental performance evaluations have proven the opposite: a solar installation produces the amount of energy required for its manufacture in a matter of 1.5 to 6 years max., depending on the quality of the silicon cells (source: Technical University of Berlin). Given that the solar cells have a minimum service life of 20 to 25 years – which is guaranteed by the manufacturers – the energy balance is quite clearly a positive one.