In the hunt for ever more reliable and efficient green energy production, the Australian National University (ANU) has developed a solar dish with an incredibly high sunlight-to-steam conversion rate. Instead of photovolatic solar panels, which convert the sun's rays directly into electricity, the so-called "Big Dish" reflects them back at a receiver, suspended in mid-air, which converts water into steam. The gas can then be used to power a motor, or stored for long periods as molten salts. The latest breakthrough is a new receiver that's 97 percent efficient. https://www.engadget.com/2016/08/23/solar-dish-sets-steamy-thermal-energy-efficiency-record/
Keep in mind that that's THERMAL efficiency, which is a lot easier. (A flat-black metal plate, for example, is close to 100% efficient at converting sunlight into heat.) Converting it into useful energy (i.e. mechanical shaft power) is where the real fun starts. With a high quality thermal source you might hit 45% efficiency if you spend a lot of money on the plant.