Best Method of Focusing Solar Power

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Discussion Overview

The discussion centers on methods for focusing solar power using a fiberglass satellite dish to create a solar-powered distillation machine. Participants explore different approaches to constructing a reflective surface for optimal heat concentration, considering both theoretical and practical aspects of the project.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant proposes molding an acrylic plexiglass mirror onto the dish to create a parabolic shape, questioning whether this would maintain specular reflection or lead to diffuse reflection due to warping.
  • Another participant expresses skepticism about the feasibility of molding the acrylic properly and suggests that gluing hundreds of small mirrors might be a more practical alternative.
  • Some participants recommend using a few larger mirrors instead of many small ones, arguing that fewer mirrors could simplify the construction process while still achieving effective focusing.
  • One suggestion includes using aluminized mylar as a reflective surface if the dish is smooth enough, citing its lightweight and highly reflective properties.
  • A participant notes that the accuracy of the focusing does not need to be excessively precise, as long as the reflected beam is smaller than the diameter of the heating vessel.
  • Resources and links to external information on solar concentrators are shared to help avoid design mistakes and learn from previous successes.

Areas of Agreement / Disagreement

Participants present multiple competing views on the best method for creating a reflective surface for the solar distillation project, with no consensus reached on a single approach. The discussion remains unresolved regarding the optimal construction technique.

Contextual Notes

Participants express uncertainty about the effects of melting acrylic on reflection quality and the practicality of different construction methods. The discussion includes varying assumptions about the necessary precision for effective solar concentration.

Thundagere
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If I keep this up, I'm going to get a rep around here :).
So, I recently acquired a fiberglass satellite dish which I plan to use for building a cheap, solar powered distillation machine. The idea is to have the dish, calculate the focal point, and run a double glass plated chamber at the focal point. THis allows light in, let's it get heated, then retains the heat long enough for it to boil. Keep in mind, as a high school freshman, this is partially for fun, but I might enter it in a science fair. I want this to be as resourceful and documented as possible.
So, here's the real question. I'm thinking of either a) Taking an acrilyc plexiglass mirror and placing it on the fiberglass dish, then putting it in an oven and molding it into the parabolic shape, or
b) Gluing on hundreds of small mirrors.

I want to know, would the first idea work or would the mirror get too warped and make light go through diffiuse reflection, or would it still be specular? Which method would be best for my project of boiling water?
With the amount of water I have, I need about 298000 J. The sun gives off about 1000 W/m^2, I believe (a bit more, but I'm averagin and including nightfall). That's just background info, but what do you guys think?
 
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Any ideas on this? I don't mean to go crazy asking but I'm honestly not sure if I can keep specular reflection when the acrilyc melts.
 
Thundagere said:
Any ideas on this? I don't mean to go crazy asking but I'm honestly not sure if I can keep specular reflection when the acrilyc melts.

It will be tough to mold it properly in my opinion. Glueing hundreds of tiny mirrors is something that I've seen be done before, but I can understand why that wouldn't be your favourite approach.
 
A few shaving mirrors I would have thought would do the trick
 
I'd say get about 10-20 small mirrors and place on the dish. They don't need to be curved, and it might be easier than making one big curved mirror or using hundreds of small ones. It really depends on how much time you want to spend on this.
 
If the parabolic dish is smooth enough you may use aluminized mylar. It's thin, light weight, cheap, and highly reflective.
 
As I mentioned before, and Drakkith re-mentions: your focusing doesn't have to be excessively accurate or excessively granular. If your heating vessel is, say, 4 inches in diameter then your mirrored tiles do not need to need much smaller than 4 inches. As long as the "beam" from each mirror is smaller in diameter than the heating vessel, you're good to go.

You'd only need a smooth surface if you wanted a point focus.
 

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