Heliostats from the Boston-based company Practical Solar calculate the position of the sun and angle their mirrors to reflect sunlight onto fixed targets. Heliostats can be used for natural lighting and “direct” thermal applications like space heating a room.
Manipulating the sun may seem like a new concept, but Egyptian tombs were designed so sunlight could illuminate dark rooms inside them. And it’s been long thought that Stonehenge was designed to have cosmic alignment with light of the sun and moon.
The cool thing about heliostats is they make the design of a home much more flexible and creative, enabling rooms to get heat and light from the sun all day—whether or not directly in the sun’s path at any particular moment. Other uses include pointing sun to shaded areas for gardening, into laundry rooms to dry clothes, or toward solar panels on a roof that might otherwise be shaded with trees you’d rather not cut down.
Complete heliostat packages with control box and software cost about $1,500, which doesn’t seem like that much considering you might not have to sacrifice getting passive solar light and heat into windows on the south side and million-dollar views on the cold north side of an otherwise well-designed house.