Campaigners claim there has never been a longer period of consecutive payments and are continuing to call for the energy regulator to investigate.
The industry has hit back, highlighting comparable payments made to power stations, but both sides agree the problem is a transmission system unfit to export enough power to England.
From April 13 to May 13 this year, some £5.994m was paid out to operators by the National Grid, with all but £2000 going to developments in Scotland. The total for the whole of 2012 was £5.924m.
The latest payments bring the total paid since January 1 to £7.8m and this week alone 20 wind farms have shared a total payout of £2.12m.
The increase in the number of wind farms in Scotland now connected to the Grid may have contributed to the recent excess power supply, but a National Grid spokesman added there could be other reasons for the payments. He said: "The end of March is the start of the summer maintenance period on the electricity transmission network, and parts of the network are taken out of service to allow that essential work to take place which can sometimes create constraints. These outages are carefully planned to minimise their impact on all forms of generation."
Last year, constraint payments were only paid out on two days in April – £37,614 on the 25th and £293,337 on the 26th. This was followed by one day the next month, May 15 when £42,942 was paid out – a total of £373,893.
Stuart Young, of the Caithness Windfarm Information Forum, said: "This was entirely predictable when a regime was adopted which allowed generators to connect to a system that was incapable of carrying the transmission. It is only going to get worse until about 2018 when we might just have a system which allows us to export to England."
Dr Lee Moroney of the Renew-able Energy Foundation, a charity which publishes the data on con-straint payments, said: "Surely it is time the regulator, Ofgem, stepped in to investigate why this is happening and to explain how these costs to the consumer can be justified."
However, Catherine Birkbeck, senior policy manager of Scottish Renewables, said: "To only focus on Scottish wind farms when com- menting on constraint payments is utterly meaningless. During the same time period [April 13 to May 13], Longannet coal-fired power station and Peterhead gas-fired power stations were paid more than £4.4m in constraint payments. In the calendar month of April these two fossil fuel powered generators were given more than £2.8m to not generate electricity while all the wind farms in Scotland received considerably less at £1.54m.
"The point is that constraints on the Grid affect almost all electricity generators, not just wind farms, and it is cheaper to compensate wind farms for lost generation time than other actions to balance the Grid."
A spokesman for Ofgem said: "Generators need to comply with all applicable laws and regulation. For licensed generators this includes the Transmission Constraint Licence Condition (TCLC) which seeks to prevent generators from obtaining an excessive benefit during periods of electricity transmission constraint. We monitor compliance with the TCLC as part of our broader monitoring activities in the wholesale market. In line with our usual practices, we cannot comment on whether a generator is complying with any regulation or legislative requirement."