I forgot to mention that as fossil energy plants (natural gas turbine plants, etc) have long stops, the government has to pay them big compensations for not producing, as anyway they are necessary to the system.

I'm from Portugal, this type of "green-article" never tells the whole story .
We have a serious problem with subsidized renewable energy , as has Spain , or Germany ( but these are rich and in Portugal we live in a severe crisis).

When there is too much wind and hydro generation, prices in the energy market fall, BUT producers of renewable energy ( exluindo large hydro ) receive the same guaranteed rate ( feed-in tariff). As these producers have priority in the system all energy produced by them have to be bought, even if there is much cheaper energy in the market (gas, nuclear, oil, etc), even if it's free as has happened several times in the past (in Germany last year energy price at one day was negative) we have to buy the subsidized energy !

So actually what happens when there is too much wind and rain ,this is terribly expensive for us, because the more subsidized energy is produced , naturally we paid more and more. Portugal already has one of the most expensive energy prices in Europe, but as the price of energy sold to public is regulated, dont reflect the real and crazy cost, consumers have accumulated a huge tariff debt to the system . In Portugal this tariff debt already exceeds 4000 million € in Spain now exceeds € 25000 million €.

To get an idea of prices paid to subsidized energy, here I leave these two pictures:
Annual change in average cost per type of energy: http://i.imgur.com/MFaPFRZ.png
Annual changes in the average cost of energy subsidized vs. average market cost: http://i.imgur.com/OFn71pI.png