"We are going to opt for the offer made by the consortium of Acwa," the source, familiar with the discussions about the contract, told Reuters. The source asked not to be named pending an official announcement due later this week.     

Acwa has teamed up with Spanish engineering firm Aries IS and TSK EE for the design, finance, construction, operation and maintenance of the plant near the southern city of Ouarzazate.     

"(Morocco's solar energy agency) Masen will make the announcement over the weekend, either Friday or Thursday. The signing ceremony will be on Saturday," said the source.    

The announcement of the deal will coincide with the expected landing in Ouarzazate of solar energy plane Solar Impulse, which took off from Rabat on Wednesday after it completed last week the world's first intercontinental flight powered by the sun.