It's not clear how the natgas output is being measured. It's used to bring the working fluid up to temperature. Either the true solar output is lower than stated or the plant is using natgas extremely inefficiently (getting 0.9 instead of 9 MW of it). In the latter case, it's still a cost of obtaining the solar energy that should be accounted for.
Wikipedia has the total and solar-only figures switched, as can be seen by visiting the citations given. The solar-only figure is 644,506 MWh.
Comments
It's not clear how the natgas output is being measured. It's used to bring the working fluid up to temperature. Either the true solar output is lower than stated or the plant is using natgas extremely inefficiently (getting 0.9 instead of 9 MW of it). In the latter case, it's still a cost of obtaining the solar energy that should be accounted for.
Wikipedia has the total and solar-only figures switched, as can be seen by visiting the citations given. The solar-only figure is 644,506 MWh.