BayWa said the takeover, for which financial details were not disclosed, will make it the largest service provider in Italy.
"The acquisition of ESS means BayWa is able to provide a broader range of services, with extensive capabilities in wind farm operations and maintenance, as well as in HV/MV substations," said BayWa Italia managing director Alessandra Toschi. She noted that ESS also has expertise in civil and electrical work design and construction.
Francesco Paolo Liuzzi, who previously served as Nordex Italy managing director for a decade, and before that was general manager of Vestas' Italian business, has been appointed managing director of ESS.
BayWa has been expanding its services business, earlier this year acquiring UK service provider Green Hedge Operational Services.
Italy's wind sector is considered mature, with market participants concentrating on increasing the efficiency of existing assets and looking towards repowering for growth.