Odeillo solar furnace | Hacker News Reader

Odeillo solar furnace

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38 pointsandrelaszlo14 comments

Talking about solar furnaces: if you are a house owner there is a lot of heating costs to be saved from building your own solar furnaces for air or water. Solar electricity is pretty ineffective (at most about 17% in commercially available solutions) whereas home built air heaters sometimes get up to 40% and water heaters almost 80%.

A friend built a solar air heater (2.55 M2) that gets almost 1kw of energy out in late February with -5c outside.

Yes! if in a temperate climate solar water heating is a much quicker economic payback than solar electric. Especially, if your house has central heating as is common in the Netherlands and Switzerland.

Dumb question: is there any difference (in terms of costs and effect) between solar panels and solar furnaces?

I mean, say you have N square meters of solar panels. If I understand it correctly, then it doesn't matter whether you make them flat or turn them into parabolic solar furnace, does it?

Yes, with furnace you can concentrate that energy on smaller area (hence more heat), but does it matter for house owners?

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.

Somebody was reading the Parker Solar Probe link that was posted earlier today :).....

Lol, I Googled it when I read it too. How can a name like Odeillo Solar Furnace not pique one's curiosity?

You got me :)

Wow, looks awesome. Has anyone visited, by any chance?

I've got to visit something similar at Sandia National Labs. https://energy.sandia.gov/energy/renewable-energy/solar-ener...

(The video at about 6 minutes shows cool footage of spaceship material being tested)

I got to see it just as a tour, I don't work in that field and don't know how it compares to the Odeillo solar furnace.

There's a group of three such power stations near Las Vegas. I passed them on the way from LA a few months ago.

https://en.wikipedia.org/wiki/Ivanpah_Solar_Power_Facility

I don't know if they permit visitors. There's something odd about the way the light makes the air glow near them. From a distance, they look unearthly; almost CGI'd.

Saw this installation on a documentary a few weeks ago. Unsurprisingly the thing is capable of instantly frying any bird that happens to fly though the beams.

I wish I had, I just finished up a month working in the area (Osseja) this summer, always wondering what that big shiny thing was on the hill across the valley. Turns out I was 18km away from this really cool structure, what a small world feeling figuring out what it was here.

Which materials withstand temperatures of 3500 deg?

Tungsten-alloys (Lightbulbs) and ceramics (Reentry Shields) are usually up on the list of materials that can withstand these temperatures, lately carbon nanostructures also joined it (Parker Solar Probe).

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