solar panel´s 

refers either to a photovoltatic module, a solar thermal energy panel, or to a set of solar photovoltatic (PV) modules electrically connected and mounted on a supporting structure.

effciencies

depending on counstruction, photovoltatic modules can produce electricity from a range of frequiences of light, but usually cannot cover the entire solar range. That depends on the weather, because if it is cloudy or raining panel does not capture the energy needed but they are a very good alternative for extra energy and that I can put on the roofs of large buildings and this could feed the entire community, could also feed around a community and you can place a source of energy savings to save this collection to surplus enrgia.

profitibleness

the cost of this service varies between applications and using it, but for small communities can be used as a secondary source of energy feeds into, besides using it to reduce the cost on your electric bill since this is a means of acquiring renobable besides energy that can be stored in containers in the form of batteries.