Acciona Energia's profits fell to EUR 539 million in the period, despite a small 1.2% increase in revenues.
The group's wind unit's earnings totalled EUR 15 million for the year to date, compared with a EUR 34 million loss in the same period of 2013.
The energy division's total installed capacity reached 8.46GW by the end of September, most of which was made up of wind (7GW).
The company said the fall in pre-tax earnings was as a result of regulatory changes in Spain and the sale of 59MW of wind projects in Germany and South Korea.
In June, Spain's right-wing government passed a retroactive law cutting support for renewable energy projects – including existing capacity.