Economically also Solar Panels are starting to approach retail electricity prices in number of places in the world.Large scale solar power plants are already selling power at 10-15c/KwH which is lower than the retail electricity prices in most places.Still competition between solar panel manufacturers,improving technology and scale are making solar panel costs come down at a rapid pace.In fact Solar Panel prices have declined by more than 50% from 2008 end to 2010 and are expected to fall by an average rate of 10% in the coming years as well.However Solar Panels are seldom bought by the customers directly but are rather bought by the solar system installers/contractors.However its a good idea to know about the costs of solar panels and systems that you are paying for and not get fleeced by unscrupulous solar installers.