Wind Mill Operation-Deduction u/s 80IA(4)(iv) of IT Act,1961

An assessee firm is a processing unit. It has installed a Wind Electric Generator (Windmill) to generate electricity to be consumed for its own processing purposes and to sell the surplus, if any, to outsiders. The assessee is maintaining separate books of accounts for its Wind Mill operations. Please clarify whether it will be eligible to claim deduction u/s 80IA(4)(iv) of the IT Act,1961 for the income from the whole of its operations or the portion relating to sales to outsiders.