SSE said it had exceeded 1GW of onshore wind-generation capacity for the first time, overtaking its hydropower capacity.
CEO Ian Marchant said 1GW was "a milestone for onshore wind capacity" and anticipated further growth for the company's wind portfolio in 2012.
Ecotricity's wind-power generation grew 13% in 2011 against 2010, with production in a particularly windy Q4 up 30% compared with the same period the previous year.
The company will install 19 new turbines at five sites across Britain in 2012 and has another 78 turbines awaiting permitting. It expects to have more than 200MW operational wind turbines by 2016.
Total UK installed wind capacity, including offshore wind farms, now stands at nearly 6GW according to industry association RenewableUK.