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Model a heliostat with a drill press, laser pointer and mirrors? Answered

Mechanical Heliostats were important scientific instruments over a hundred years ago and one mirror heliostats were often used to focus sunlight on an experiment. Better mirrors became cheap and 2 mirror heliostats replaced them. Then electric light killed off both types.
But now, solar energy is becoming important again. Big fairly low efficiency mirrors can be made with mylar stretched across a frame.
Perhaps now is the time to get 1 mirror heliostat research going again!
(With low efficiency mirrors, 70% efficiency becomes 49% if you use 2 mirrors to reflect the light) So you get less efficiency for twice the expense if you use 2 mirror heliostats!
But first we need to model the process. It just takes too long to test your ideas outside!
Here is the start of my model of mirrors on an equatorial mount (also called a polar mount) and the sun moving on the celestial sphere. I think that it will end up being very useful. I just gotta find the right mirrors and the right laser pointer. A heliostat with the mirrors moving at one rotation every 2 days, can do this perfect reflection but it is limited to certain angles because the mirror must be upright on the mount.
In my model, I have left out the earth's surface for them moment. So we will just model the suns movement, the heliostat mirror movement and have a target to see how much the reflection moves too.



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12 years ago

70%? I thought Mylar was like 92-96% I hope it isn't 70...


Reply 12 years ago

I was just thinking of dust, splashes, "field conditions" and materials that are sold as (but are not actually) Mylar. In BC we have "hydroponic" stores and the price difference between their mylar products are great. And I was trying to show how quickly efficiency deteriorates when a 2 mirror "solution" is used. The long term reason for the project is to help poor people. They are not likely to have access to high quality mylar but they might have access to the thermal blankets sold in dollar stores. Anyway 92 to 96% is off the roll. We must accept that things degrade. If you use the thing for a season, you need to put a realistic figure in. 80% perhaps? which gives 64 % (and double the cost) for the 2 mirror solution.