NTR is to take a controlling interest in a US-based company which develops solar powered electricity generation plants.
NTR is investing $100m (€63m) for the stake in Stirling Energy Systems (SES), which is based in Phoenix, Arizona.
SES is developing what NTR says are two of the world's largest solar power projects, which will supply southern California. Between them , the two will produce up to 1,750 megawatts of power when completed.
SES already has agreements for the purchase of the electricity with two of California's leading utility companies. SES uses a technology called the SunCatcher, which combines a mirrored concentrator dish with a Stirling engine designed to convert reflected sunlight into electricity.
Earlier this year NTR completed the sale of wind energy group Airtricity. Chief executive Jim Barry said it had been pursuing other similar opportunities after the Airtricity sale.
