# How to Use a Parabolic Curve to Collect Sun Energy

A guide to use a parabolic curve to collect sun energy, includes parabolic curve myths, standard authorities information to construct a parabolic reflector and diagrams.

| September/October 1977

Diagram: How to use a parabolic curve to collect sun energy.

Illustration by the MOTHER EARTH NEWS staff

You can use a parabolic curve to collect sun energy using this helpful guide.

## How to Use a Parabolic Curve to Collect Sun Energy

Solar energy is in! All the way in . . . as a quick glance at almost any magazine, newspaper, or evening television news. cast will demonstrate. Everyone, it seems, is now interested in substituting some of the boundless energy from the sun for our increasingly expensive fossil fuels.

And that's relatively easy to do for a few fortunate folks . . . the ones with enough bucks in their bank account to just go out and buy the "latest and greatest" solar energy hardware on the market.

Most of us, however, have more ambition than money. In short, if we expect to harness the sun for our own personal use any time soon, we're probably going to have to go down into the basement or out into the workshop and build our own hardware. Which is where the rub all too frequently comes in: Far too many would-be constructors of do-it-yourself solar equipment are ready, willing, and able to fabricate the gear they want . . . but they simply don't know where or how to begin . . . especially when it comes to one of the most efficient solar collection devices of all, the parabolic curve.

Ah, but that's exactly where I can be of help. I've been calculating, constructing, and working with parabolic curves for years and I've come to the conclusion that it's no wonder parabolics baffle so many would-be solar energy experimenters: The amount of downright false and misleading information about them currently in circulation is appalling.

Suppose, for instance, that you desire to create a parabolic mirror, or half-mirror, or extended half-curve of rectangular shape (see Figure 1). You know you need to calculate and draw the supports and surface for the mirror you want . . . but that's about all you know. So you begin to look around and — hot dog! — you discover an article or an advertisement or some other piece of literature which glibly leads you to believe that almost any old curve will do the job.

### MOTHER EARTH NEWS FAIR

#### Sept. 15-17, 2017 Seven Springs, PA.

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