This is a bit more complex to describe. Here’s how it works.
Take two disks of glass, one black, one clear. Let us say they are 4″ in diameter, of indeterminate thickness.
Now take a ring, say 1″ thick, 4″ in diameter, made from a strong insulator. Separate the two disks with this ring, enclosing some air.
Now evacuate the air, leaving a vacuum gap between the two glass disks, except at the edge of each disk, where the ring holds them apart.
Now place this ring into, say, the top of a highly insulated box. Let us say the black side of the “Solar Energy Diode” faces into the box.
Infrared energy will pass through the clear disk, hit the black disk, be converted into heat, and then trapped inside the box by the vacuum gap between the black and clear disk. In this way, incoming solar energy can be trapped inside of the box, with only a little energy escaping back through the black disk, vacuum, and clear disk into the surrounding area.
In the converse case, the Solar Energy Diode is turned around, black disk out, making heat flow more easily in the other direction. In this orientation, black body radiation from the items in the box flows through the clear disk, through the vacuum gap, and then strikes the black disk, being converted into heat.
An exercise for the interested reader: can a half-silvered mirror (a one-way mirror) be used to make this Solar Energy Diode more effective?
Couple with a solar funnel to create an effective solar oven, or with a solar funnel, pointed at the night sky, with the disk in the “black-side-out” condition, to create an effective solar refrigerator.
Who’s going to manufacture???