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What should I build a solar dish out of?

2007

Hi everyone,
I have been spending lot of time around the internet, trying to figure out how to build a cheap, self-made solar dish to produce (very) hot water.
I have been investigating every possible reflective material, metals included, but still I can't understand what could be good and what would be not.
I thought of aluminum, stainless steel, brass (and many more), and different coating/polishing/anodizing procedures, but I do not know if these will reduce reflectivity.
As I need a long-lasting, resistant and highly reflective material, what do you think is best?

Thank you,

Giovanni Casagrande
Hobbyist - Bologna, Italy

High purity aluminum, bright dipped and with a minimal thickness of anodizing, should prove very economical as well as very highly reflective.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2007

2007

Thank you very much for the answer.

So, stainless steel is not a good idea at all? Why?
And, could you suggest any technical data on the aluminum solution (i.e., which alloy is better, thickness on anodizing layer, buffing solution).

Thanks again.

Giovanni Casagrande
- Bologna, Italy

ASM Metals Handbook Vol. 5: "Surface Engineering"
asm_vol5new

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2007

I don't work in the solar field so I can't quote absorbtivity, emissivity, and similar parameters for the various metals without research, Giovanni -- but some materials that appear to be bright and reflective are not good reflector material. For example, to the surprise of most people, chrome is a very good absorber and a poor reflector. Similarly, stainless steel just isn't a good reflector.

For the aluminum, look into reflector design subjects. In general the pure aluminum alloys, 1000 series, are the finest reflectors, but other alloys work well. As a general text, ASM Handbook Vol. 5 covers the subject of finishing aluminum reflectors and mirrors quite well. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.

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