Mandatory solar panels in Spain

Spain have taken the plunge to really drive forward solar power -if it should work anywehere you'd think Spain would be it eh? One interesting point of criticism:

"critics of the Government’s plans say that the installation of solar panels would increase construction costs by between €1,100 and €1,400 per dwelling."



Which is no doubt true but what is the truer equation -ie; how much does it save in power costs and how quickly do those savings pay for themselves? It's a bit like criticisning building regulations for stipulating that certain safety features should be mandatory in buildings; yes it costs more at the point of purchase, but that's not the point