For years the complaint against offshore wind was prohibitive cost. The new worry is that it is suddenly becoming too beguilingly cheap.

The world’s biggest wind companies are driving down power contracts so fast in their coat-throat battle for market share that they may be making impossible commitments. The sums of money at play are huge, and the stresses may not come to light until the financial cycle turns.

A string of tenders this year have slashed strike prices to once unthinkable levels. The Danish giant Dong Energy stunned the industry in July by clinching an offshore deal in the Netherlands at a strike price of €72.5 per megawatt hour (MWh), half the sorts of levels agreed less than five years ago.

Known as Borssele 1 & 2, the project was quickly surpassed by an even cheaper bid of €60 per MWh by Vattenfalls in a Danish tender. "My world record was blasted away in weeks," said Rene Moor, head of wind management for the Dutch government.

The auctions have become intoxicating. "There's bidding fever going on, and it can be very addictive," said Ranjan Moulik, an energy specialist at the French bank Natixis.

The Danish deal is roughly half the strike price for the Hinkley Point nuclear project – now £97 per MW, after adjusting for inflation. It is shockingly cheaper, even taking into account the problems of intermittency and the peculiarities of the Danish system.