DUBAI (Reuters) - The United Arab Emirates (UAE) on Sunday officially opened its first big solar energy plant, the three companies behind the project said in a statement.

The 100-megawatt (MW) Shams 1 concentrated solar plant (CSP) took the UAE's Masdar, France's Total and Spain's Abengoa three years to build at a cost of around $600 million.

Shams 1 is one of the largest CSP projects in the world and by far the largest solar plant in a fossil fuel reliant region that lags far behind much of Europe, the Americas and Asia in renewable energy.

"The region is faced with meeting its rising demand for energy, while also working to reduce its carbon footprint," Masdar Chief Executive Sultan Ahmed Al Jaber said in a statement to mark the opening of the plant.

The UAE's richest emirate is targeting 7 percent of electricity from alternative sources by 2020. By comparison, that goal was exceeded by 21 of the 27 EU member states four years ago.

Despite vast expanses of empty desert and intense year-round sunshine, solar energy has struggled to take off in the Gulf where heavily subsidized fossil fuel makes green investments less attractive than in countries that subsidies renewables and tax fuels.

Shams 1 capacity, which is 10 times larger than the next largest plant in the country, is enough to supply 20,000 UAE homes and will be especially useful for meeting peak demand on hot summer days.

By comparison, Germany and Spain have installed many thousands of megawatts over the last few years, and India has built over 1,200 MW of solar power.

This imbalance in global green investment could be changing, as economic woes limit European spending on expensive green technologies and as wealthy oil and gas exporting countries of the Gulf try to cut the use of fuels that they could export.

Saudi Arabia, which has said it aims to becoming a major generator of solar power, has built less than 50 MW so far. It has plans to build up to 41,000 MW of solar power over the next 20 years, more than any country has built so far.

(Reporting by Daniel Fineren; Editing by Alison Birrane)