Riyadh and Japan’s SoftBank has signed an agreement to develop 200GW of solar energy throughout Saudi Arabia, as part of a programme which will require up to $200bn investment.

The preliminary agreement was signed by Saudi Crown Prince Mohammed bin Salman and SoftBank CEO Masayoshi Son in New York on 27 March. Mohammed Bin Salman is currently on a three week tour of the US, undertaking diplomatic meetings and signing business deals worth billions of dollars.

The first phase of the solar project will require $5bn of investment and is expected to begin before the end of 2018. The first phase is aiming to develop 7.2GW of solar energy in 2019. Both sides will put up an initial $1bn for the first phase, with the rest to be secured through debt financing.

“It’s a huge step in human history,” said Mohammed bin Salman at a press briefing following the signing of the agreement. “It’s bold, risky and we hope we succeed.”

SoftBank is set to play a major part in Saudi Arabia’s economic reform programme, with the two sides planning to develop a $100bn technology investment fund. The initial agreements for the fund, to be called the SoftBank Vision Fund, were signed in October 2016.