Germany already produces 50% of its electricity consumption from the Sun... at midday

Erlasee solar park

It is by the moment only at midday but that is already whole world record and the way of Germany out of the nuclear energy trap.

This is certainly something in which Spain or Greece, countries with significantly much more solar input, could well imitate the Central European powerhouse. Of course it requires significant public investment to kickstart the production and that seems out of the question today but in fact it would importantly reduce the oil bill in the mid-run.

Whatever the case, the German example evidences that clean energy and development are not at all at odds, rather the opposite. Even Conservative actors, typically most reluctant when it comes to the environment, have realized in Germany the importance of developing renewable sources of energy. 

Critics complain that the scheme adds 2 cents of cost per Kilowatt, with prices already very high (23 cents/Kw, almost double than I pay here). The price is however politically determined and could surely be lower. 

On top of this record production out of sunlight, Germany also produces as much (somewhat more) from wind farms.  In 2010 it was 17 GW from solar and 27 GW from wind (but solar is growing quite faster these days).

Ref. Reuters.

The efficiency and potentialities of of solar energy production have been decreasing in the last years quite fast:

Click to expand - source: Wikipedia

Some technologies achieve already more than 40% efficiency rate. Others, while less efficient, are also cheaper to produce and easier to install. In general the efficiency has doubled or more in the last two decades and also (not apparent in the graph) the materials used have been reduced in cost. It is still a tad less economically efficient than burning gas or oil, if we do not consider the environmental costs, and has the problem of not being a la carte (you don't produce solar energy by night, so you have to store it somehow, with conversion costs, or use some other source). That is why a broad-spectrum energy strategy is always needed, including reduction of unnecessary expenditure by, for example, properly isolating homes in construction. But we must consider that oil and gas are every day more expensive, while their sources, almost invariably from remote lands, are often problematic and uncertain, and, very specially that burning causes pollution and global warming, renewables are the way to go - clearly so. 

Proportion of renewable energy in EU and some other states five years ago (from Wikipedia)