* France a net importer from Germany every month in 2012
* France's biggest clients are Switzerland, Italy and Belgium
* French nuclear output down in 2012, short of EDF target (Adds quotes, details)
By Muriel Boselli and Michel Rose
PARIS, Jan 22 (Reuters) - France's net electricity exports fell by nearly a fifth in 2012, hit by competitive German electricity produced from cheaper coal and booming renewables, French power grid operator RTE said.
The power export surplus dropped by 21 percent in 2012 to 44.2 terawatt hours (TWh), although France remained the European Union's biggest electricity exporter, RTE said in its annual report on Tuesday.
For the first time ever, France was a net importer from Germany every month of last year, added RTE, a subsidiary of former power monopoly EDF.
"This situation is quite paradoxical at first glance because Germany stopped seven nuclear reactors in March 2011," RTE said.
German power exports increased due to a big expansion of its solar power capacity and because coal-fired power plants became more competitive, RTE said. Coal prices have dropped as a result of lower demand in the United States, which has massively developed shale gas production in recent years.
The share of Germany's power production coming from renewables such as wind turbines and solar panels increased by 1.6 percentage points to 21.9 percent in 2012, industry group BDEW said earlier this year.
Germany's subsidised renewable power has priority grid access and flows throughout Europe via interconnections. When renewable output is high in Germany, this weighs on its spot prices and makes its power attractive in neighbouring countries.
"Can we predict whether Germany could become Europe's biggest electricity exporter? I don't know," Dominique Maillard, the head of RTE, told reporters at a news conference.
"At some point France will also have surpluses of renewable energy production to offload, which will weigh on its spot prices," he said.
In 2012, France exported 5.2 TWh to Germany while it imported 13.9 TWh, bringing net imports to 8.7 TWh. France's biggest clients remained Switzerland, Italy and Belgium.
In 2011, France exported a net 2.4 TWh to Germany after Europe's largest economy shut nuclear reactors following Japan's Fukushima disaster.
Excluding the impact of weather, electricity consumption was stable in 2012 at 480 TWh once the closure of energy-hungry Eurodif, an uranium enrichment facility, was taken into account, RTE said.
While demand from industry fell by 4 percent in 2011 and 2012, household consumption has risen continuously since 2002, with a 2.4 percent increase in 2012.
Power consumption fell the most in the car and steel industries.
"Aside from the crisis-related impact, the trend reflects the evolution of French industry, which has become less energy-intensive," RTE said.
Including the impact from weather, electricity demand climbed by 2.1 percent from the previous year because of a cold wave early in the year that pushed demand to record levels.
On the production side, output eased by 0.3 percent to 541 TWh, led by a 3.8 percent fall in nuclear production especially during the summer months, RTE added.
French nuclear production fell to 404.9 TWh in 2012 after EDF had to carry out more maintenance than expected at its fleet of 58 nuclear reactors. The figure compared with a forecast for an increase to 420-425 TWh, which EDF made in February last year. (Editing by James Jukwey and Jane Baird)