You can build a well sized solar air box that will help heat your house for around a hundred dollars or so depending on the materials you have at hand. It's not complicated but you will need basic construction skills and some time to work through the job.
Step 1: Size the Box
The first thing to do is figure out where you want to place the box or boxes you build. I have found out that bigger is better when it comes to solar air heater boxes.
Find the best and biggest not shaded south facing area you can.
Prepare whatever foundation and side installation mounts needed. In the photo I used 4"x4" posts to hold the two 3'x12' boxes and attached them to the side of the house using wood screws into both the window frame and strip glued to the side of the house. This has worked in high winds, rain, and snow.
The sun provides about 1,000 Watts of energy per square meter of space. That is about 10.8 square feet. For comparison, a sheet of
4'x8' plywood is 32 square feet or about 3,000 Watts capability! Notice that the space heaters you get at like Home Depot or Walmart
pull about 1,500 Watts each out of the wall.
So a sheet of plywood sized solar box can give you 2 space heaters of energy in theory. However, your solar box is probably not as efficient as a space heater, so the energy - heat you get out is actually less.
Parts you need:
Plywood or other backing...I used old doors.
Screws, nails and good waterproof carpenters glue
Guerrilla Glue - optional but it rules!
100' of 3 inch drain hose - about $55 bucks of you can buy 10 foot sticks at about $6/stick
Expanding foam - minimal expanding this stuff is the best foaming/fixing drain hose and filling big cracks.
Expanding foam - maximum expanding for the window openings
Tape measure - 25' for big boxes
14 mil woven poly plastic from ebay or your choice of covering. I used the poly and that is what I describe here.
Staples (3/8") and staple gun. You can use other fasteners like maybe roofing nails or something, but it is hard to beat a staple gun.
Plastic rope or cord to fix (staple) the hose to the back of the box.
Caulking for sealing up the window inlets
A jig saw or coping saw