Solar Furnace Project

Function

• Solar furnaces are equipped with a curved lens or mirror that reflects sunlight to a central point, which creates a source of energy. A lens or mirror attached to a solar furnace works like a magnifying glass, because it directs sunlight to a single point that gets hot enough to burn or melt materials in its path. Therefore, it’s important to keep a solar furnace out of the sunlight when it’s not in use to avoid generating heat unintentionally.

Kilns

• Some solar furnace projects involve creating an outdoor kiln to melt metals or fire clay jewelry and other objects. A “Mother Earth News” article describes how to build this type of solar furnace using lumber, plywood and firebrick. For this project, a round Fresnel lens with a 14-inch diameter captures the sunlight needed to heat the furnace. The lens has several grooves on it that sit at slightly different angles to direct sunlight toward a central point to produce intense heat. Online merchants who sell prisms and magnifying glasses usually sell Fresnel lenses, too.

Kits

• Solar furnace kits are available for school science projects. For example, American Educational Products markets a furnace designed to demonstrate the intensity of the sun’s heat. The furnace consists of a round, concave dish with a 12-inch diameter. A reflective mirror directs sunlight toward materials in a copper container attached to the dish. The furnace can produce temperatures exceeding 300 degrees Fahrenheit that can cook or melt items in the container.

Considerations

• Some online information posted by renewable energy organizations and bloggers includes directions for making solar panels to heat a home. The panels usually are equipped with fans that blow warm air into a home that’s generated from the sun’s heat. By definition, these devices aren’t true solar furnaces. The Service Magic contractors’ website notes that solar furnaces aren't used for residential heating due to their prohibitive costs. Commercial solar furnaces, for example, can cost millions of dollars to erect, according to the site.