That is an awesome question I was just wondering the same thing designing a passive solar heating and cooling system for a greenhouse or home and no it hasn't been done according to all my research I was thinking of using salt or sand for heat absorption I feel like blacksand or crushed asphalt may work the best I feel like if I ran air lines through a wall filled with black sand or crushed asphalt behind a plane of glass with a wall of 2ftx2ft Fresnel lenses just far enough from the wall so that the focal point was just at the sand it would supper heat it even as the focal points moved with the sun and with proper vent design you could either pull cool air into the structure or circulate the hot air within only using the convection current which would be created
