NTR has invested the money in the US-based firm Stirling Energy Systems (SES) after reaching an agreement that will give NTR a controlling interest.

The funding will allow SES to begin work on two major solar farms in southern California and increase its production of its SunCatcher solar energy generators.

The SunCatcher technology uses large mirrored dishes to direct sunlight onto an engine capable of turning the energy into electricity.

The technology has been in testing at US Department of Energy laboratories.

Jim Barry, chief executive of NTR, said: “This is a very exciting investment for NTR.

“In SES, we have a partner with high growth potential and a leading cost position in the fast growing concentrating solar power sector.”

He added: “We have been actively pursuing such investment opportunities.

“SES is a particularly attractive business opportunity with very significant future development potential.”

NTR is a developer and operator of renewable energy in the UK, Ireland and the US.

Its sustainable waste management business, Greenstar, is the largest of its kind in Ireland.

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