"To help feed the country’s population, an inventor, Toufic Hamdan, created a commercial bakery to bake bread in solar ovens. The startup “Partners With Sun” has installed a solar convection oven on the bakery’s roof. The Solar Oven uses large silver mirrors to capture and magnify the sun’s rays to build heat. The heat is transported by a transfer fluid which is then used to help operate a convection oven, allowing it to reach a baking temperature of between 300 and 400 Celsius. The heat is used directly in food and beverage production. " Baking Bread in a Solar Oven | Happy Eco News
According to the company website, “The Solar Oven cuts up to 80% of the bakery’s fuel bill.”
The efficiency of light ->electricity -> heat is about 20%
Solar heating can have efficiencies as high as 80%, although in this case because the heating is indirect and the temperature is elevated, the efficiency is likely somewhat lower.
If you need heat, best get it straight from the sun!