A solar "furnace" for air heating is just a box with a collector (most efficient ones are regular black insect screen collectors), which makes them a lot cheape

A solar "furnace" for air heating is just a box with a collector (most efficient ones are regular black insect screen collectors), which makes them a lot cheaper than a solar panel. Depending on how you have to transfer the air into/out of he collector the price difference can be huge. I am building one now where the material cost for 5 m2 of collector with ventilation will be just shy of $650 and then I am using a very fancy collector mesh which I am not even sure will bring much. The ventilation will also be expensive in my case. Similar panels can be made a lot cheaper, especially in the US where material is cheaper and more readily available. That size would give me about 850w with solar electricity panels and I am counting on 2kw with my collector (if I can get air through it quickly enough). For my size (5m2), the price difference is about a thousand dollars, and I will get twice as much energy out of it. You should check out www.builditsolar.com and search on YouTube for solar furnaces. Edit: oh, and solar water heating is of course even more efficient. 300m 4cm matte black PEM pipe on your roof is an excellent 10kw pool heater, costing just a couple hundred bucks. Payback is just a month or two depending on how fancy you want it.