Desalination infrastructure is expensive. If you get 54 million gallons from a $1 billion plant, you need to spend twice as much if it only runs 12 hours a day.<p>Storage costs are not free, but if you can save 1 billion then that buys a <i>lot</i> of battery&#x27;s.  It&#x27;s ~15,000 kilowatt-hours of power for every million gallons of fresh water that’s produced.  If you assume 1&#x2F;2 of your production is at night that&#x27;s 405Mega Watt Hours of storage which is less than 1 billion, though at 2,000$ &#x2F; kWh battery&#x27;s not by all that much.<p>A better option is to just pump water up a hill to a lake, which could then provide whatever pressure desalination needs at the bottom of a hill.  But, again that requires a tall hill. (~65 ATM * 33 feet = ~2,145 feet above sea level.)  Saudi Arabia actually does have a lot of land at that altitude or above.<p>PS: This is also why you run them at night in the first place.  We really don&#x27;t need a lot of water at night, but storing water is cheap.