Saudi Electricity Company (SEC) has extended the commercial bid submission date for its planned 550MW Duba 1 integrated solar combined-cycle (ISCC) plant.

Contractors now have until 15 May to submit commercial proposals for the project. The previous submission date was 2 April.

According to sources close to the scheme, the deadline has been extended to allow groups more time to submit bids.

In November, MEED reported that SEC had received technical bids for the contract to build the Duba 1 plant.

The Duba 1 ISCC is planned to run on a mix of natural gas and solar energy, and will have a total development cost of $600m. The plant will have a guaranteed total output of 485-550MW, which will include 40-50MW output from the solar system. The planned commissioning date of the plant is 2017.

In January, SEC awarded the US’ GE the original equipment manufacturer (OEM) contract for the project. GE’s order includes two F-class gas turbines, a steam turbine, generators, heat recovery steam generators, a condenser, a control system and long-term service agreements.

MEED reported in April 2014 that SEC had dropped plans to develop the Duba 1 scheme as an independent power project (IPP), and was instead preparing to tender the plant as a standard engineering, procurement and construction (EPC) deal. SEC has split the project into two contracts: an EPC deal; and an OEM contract.

Duba 1 is the second ISCC that SEC is moving ahead with, with the utility having also invited contractors to submit commercial proposals for the planned ISCC at the Waad al-Shamal industrial development in the north of the kingdom. The Waad al-Shamal facility will have a combined-cycle gas component of 1,000MW and a 50MW concentrated solar power (CSP) component.