Portugal’s energy needs were completely provided by renewable sources in March, according to a press release from the Portuguese Renewable Energy Association (APREN).

The 4,812 GW produced by renewable energy in March exceeded the 4,647 GW in consumption for mainland Portugal for that month. The 103.6 percent of energy consumption produced by renewables was the highest in four decades.

Rooftops in Lisbon, Portugal's capital and largest city.APREN estimates that the banner month saved 1.8 million tons of CO2 emissions, resulting in €21 million worth of emissions allowances. It also lowered the average daily wholesale market price by over 4 euros compared to the same period in 2017.

A common criticism of renewable energy generation is its intermittent nature, which played a part in Portugal’s record month. The daily share of renewable energy bottomed out at a still-respectable 86 percent of consumption on March 7 and hit a maximum of 143 percent on March 11. Two long stretches of around 70 hours, one beginning on March 9 and one on March 12, saw 100 percent of consumption provided by renewable sources.

The same intermittent nature meant that the country needed to complement its energy supply with thermal fossil fuel power or imported energy. But these periods were compensated by later ones in which renewables provided more than enough power.

An April 3 Reuters report pointed out that an exceptionally rainy month enabled the stellar generation numbers. Portugal received four times the monthly average rainfall, refilling depleted reservoirs and boosting hydroelectric generation.

Portugal’s March renewable mix was led by hydropower (55 percent) and wind (42 percent). In times of more conservative rainfall, wind power leads renewable power sources. The country also generates significant power from biomass, and to a lesser degree solar PV.