How to Heat a Basement With DIY Solar Panels

Cut two pieces out of one of the 8-foot-long 2-by-6 boards, each two 3-foot-9-inches long. Screw those pieces between the ends of the uncut 8-foot 2-by-6 boards to make a rectangle frame 8 feet by 4 feet and 6 inches deep.

Attach the full-sized sheet of plywood to the frame, spacing the screws about 1 foot apart from each other. Turn the frame over, so that it makes a rectangular box.

Cut out a rectangle of metal 3-foot-9-inches wide by 7-foot-9-inches long, with the metal-cutting shears. Epoxy the metal to the bottom of the box.

Drill a hole in the left corner of either of the short ends, in the bottom. Make it the same width as the flexible duct. Push one end of the longer duct into it. Seal the joint between the duct and the box with epoxy. This end is the lower end of the heater.

Drill a hole in the right corner of the other short end. It too should be as wide as the duct. Set the other duct in this hole in the same manner as the first. This is the upper end of the heater.

Set one end of one of the 3-foot 2-by-6 boards up against the left inside wall of the box 1 foot 8 inches up from the lower end. Screw it into the box there.

Put one end of the other short 2-by-6 against the right wall, 3 foot 4 inches away from the bottom end. Screw it into the box there. These boards work as baffles, to give the air a longer, meandering route as it rises. This allows it more time to warm up.

Paint both the inside and outside of the heater black, to help it absorb heat better. Epoxy the acrylic sheet to the top of the heater.

Cut a rectangle of plywood as wide as your window is wide and taller than the ducts are by at least 1 inch. Cut two holes, each as wide as the ducts.

Open a basement window that's in a south-facing wall. Place the piece of wood with the duct holes into that window, and hold it there by lowering the window onto the top of it.

Lean the upper end of the heater on the wall over the window, and run both ducts through the holes in the wood. The duct from the lower end of the heater should sit near the floor. Run the free end of the duct from the top of the heater up toward the ceiling, and tack it to the wall.