How to Build Solar Heaters

Diagram of solar heater

Solar heaters can be used to heat water or heat air. For this article, the focus will be on solar heaters that heat the air in your home. These heaters can be installed indoors or outdoors. Generally, solar heaters installed outside the home, on the roof or the south side of the house, will produce more heat. Below are instructions for building an outdoor solar heater.

Things You'll Need

• Double-insulated glass (by itself or as a window)
• 1-by-4-inch or 2-by-4-inch wood planks
• 1/2-inch plywood
• 1.5-inch insulation board
• Knife
• Jigsaw
• Drill
• Aluminum or copper flashing
• Screws
• Two eared ducts
• Two wall plates
• High heat, flat black paint
• UV-resistant weather stripping

Instructions

1. Using 1-by-4-inch or 2-by-4-inch planks of wood, build a frame that will fit the glass. For this example, a 4-by-5-foot double-insulated glass from a double-paned window will be used. Set the glass/window aside as you make the frame. Nail a 1/2-inch plywood panel to the back of the frame. Line the interior of the panel with a 1.5-inch insulation board. The insulation board should be cut to fit and should set in place without glues or fasteners.

2. Cut aluminum or copper flashing to fit inside the frame. Place the flashing on the insulation board. You shouldn't need glues or fasteners. The flashing works as the heat absorption plate. Add 3/4-inch-thick strips of insulation board to line the sides of the panel.

3. 

   Add the interior frame boards and baffles that are approximately 2 inches tall. When the glass is added, these boards must seal to the top of the glass. Cut the wood to ensure there's no space between the baffles and the glass. Screw the baffles in a zigzag pattern (see image), approximately 10 inches apart. The baffles should be 2 inches below the opposite side of the frame from which they are screwed on. Apply weatherstripping to the exposed end of the baffle board.

4. Cut an a 5-inch-diameter opening in the lower left of the panel and one in the upper right (or vice versa). These are your ventilation panels. Mount the panel to the outside wall or roof. Ensure that you are securing the panel onto a stud or roof beam and that the ventilation holes do not line up with a stud or beam.

5. Depending on where you've installing the panel, cut a 5-inch hole through your (south-facing) wall or roof using a 5.25-inch hole saw bit that lines up with the heater's ventilation holes. Measure the distance from the panel to the opening indoor to determine how long a duct you need. Add the eared connector to the duct work and slide through hole. Seal around the duct with silicone and bend the ears over to secure in place. From the inside, add a wall plate for a finished look. Secure the plate to the wall with screws. While you may want to install a fan, most heating panels will work fine without a fan as the air will move by convection -- meaning cold air will enter the bottom and rise out of the top as it is heated. The air may not move as quick, but it will come out much hotter.

6. Going back outside, paint the inside of the heater with high-heat, flat black paint. Apply UV-resistant weatherstripping to the top of the baffles and interior frame pieces. Screw the window frame if using a window; if not, merely screw glass to the panel. The glass should set tightly to the weatherstripping so no air can pass over the top of the baffles. Your solar heater is now set to go. When not in use, plug the holes inside the house with foam or insulation.

References

• How to Build an Outdoor Solar Heater

Resources

• Read this Article in Spanish
• Rules for Spacing Baffles
• Indoor Solar Heater How-to
• Inexpensive Solar Water Heater DIY