Each installation of power from renewable sources includes a "green power certificate" for every 1,000 kilowatt-hours (kWh) of capacity, worth about €330 per megawatt- hour, which can be sold on the open market or for a fixed price to electricity companies. Critics of the price rise say energy provider Eandis is using new sources of cheaper electricity as an excuse for customers having to pay more for electricity - including those who have not installed solar panels.

According to Eandis, the extra cost of all those solar panels - €543 million between 2009 and 2011 - has to be recouped. "No-one could have predicted the incredible success of the premiums," a spokesman said.

But according to BelPV, the federation representing the photo-voltaic industry, which makes and installs solar panels, Eandis has employed "disinformation" in claiming a price increase of €6 a month per home. The real cost to them of the green power certificates, claims BelPV, was more like €2 a month per home.

BelPV described the reasoning of Eandis as "intellectually incorrect". Eandis reckons its costs at €543 million; according to BelPV, the true price is €175 million for this year, and €190 million for 2012.

The association also points to the massive profits made by Eandis' major shareholder, Electrabel, from the continued use of nuclear power - something that in recent weeks, following the Japanese nuclear crisis, has come under renewed scrutiny. BelPV points out that Infrax, the other main distributor in Flanders, estimates its own costs at about €2 a month per client.

About €142 of an average family's annual payment to Electrabel is for nuclear energy that costs Electrabel next to nothing. Eandis makes about €240 million a year in profit, a third of which goes to Electrabel.

The Gezinsbond, or Family Union, meanwhile, said that passing the cost of the certificates for solar installations along to private consumers was "unacceptable", while companies were installing far larger solar installations and escaping the price increase. "Households install relatively small solar installations to cover their domestic consumption,"
the Gezinsbond said in a statement. "Large industrial installations take up 40% of the certificates, and yet energy intensive industries are exempt from the price rise."

Pictured: Solar panels blamed for dearer electricity