Solar Reflectors?

Nomad

Have seen this several times - Can't see where it'd make much difference on a nice, bright sunny day. Any value to it on a marginal day?

mickietucs

Following --- wonder....

Tabaz

I believe this is how the Pod People receive communications from their Mother Ship.

JustJohn

OutbackAZ said:

I believe this is how the Pod People receive communications from their Mother Ship.

Would that be the R Pod people?

Tabaz

JustJohn said:

OutbackAZ said:

I believe this is how the Pod People receive communications from their Mother Ship.

Would that be the R Pod people?

No JustJohn.  The "OTHER" pod people.

Tabaz

However, there is an uncanny similarity . . .

Nomad

Ok, where are all the solar geniuses that can usually calculate everything to the nano watt hour?

Tabaz

They are already on the Mother Ship! 
Seriously, what possible purpose is there for putting tinfoil in front of a solar panel?
reflected sun is directed up and away?

Nomad

Don't have a clue, that's why I asked - Seen it several times - Thought maybe somebody knew something I didn't.

irvingj

Back when I was working at a middle school, we participated in yearly Junior Solar Sprint competitions. Each team had the same solar panel and the same small electric motor, but everything else was up to the kids (and their coach) to design. We found that being able to tilt the solar panel --as opposed to being just flat on top of the model car-- did help, but the benefit wasn't worth the weight and complexity.

Bottom line, yes, it can help, but generally not worth the effort/expense. One other thing to keep in mind is the drop-off in efficiency as the solar panel gets hotter.

And yes, we did walk away with a large trophy on several occasions, covering 20 meters in less than 6 seconds from a dead start.

leenscottfl

Sorry irvingj but these folks disagree with you about tilting.

https://www.youtube.com/watch?v=G01A51L-5Vc

Nomad

I find tilting and redirecting a couple times a day make a big difference. Still not sure about that reflector though.

Verna

Tilting has worked well for me. While I know it is better to redirect, sometimes I just don't remember to do it. As far as reflecting, it would take so many mathematical calculations to get the aim coordinated, that I would have left that campsite a week ago 

ChanW

I think I once read something about a magnifier helping solar. 

Like a giant Fresnel lens?

http://www.solarnovus.com/mirrors-vs-fresnel-lenses-for-concentrating-solar-power_N7202.html

Here's a video of a test a guy did: https://youtube.com/watch?v=5uGex_wGa7s

jkjenn

leenscottfl said:

Sorry irvingj but these folks disagree with you about tilting.

https://www.youtube.com/watch?v=G01A51L-5Vc

Although there is some benefit to tilting, the largest benefit from tilting is gained when the sun's overhead angle is at the lowest position. For most locations in the lower 48, that would be during winter. Technomadia (Cherie and Chris) don't tilt because of the pain it is to climb the roof of their bus. They would agree that the gain, for them, isn't worth the effort. I redirect and tilt of I am around and have time but I have always added a little more wattage in my array to compensate for not always being able to tilt and redirect.

If your panels are positioned so that they are in shadow from other objects for part of the day and if the reflector filled in those shadows I can see there being some benefit, but reflected light is not as strong as direct light.

Just my 2 cents.

irvingj

Very good video, nicely done.

Think I was having a senior moment… yes, I know tilting does work.

In our case(s), however, we all competed at the same time, late spring and early summer, so we didn't have such a low solar angle. Our competitions also took place late AM through noon to maximize what solar energy we did get, so the benefit from tilting wouldn't have been so pronounced.

Since our main goal was acceleration, weight became a major issue. Also, sometimes the track surface was a bit rough, so any mechanical complexities would quickly show up as "things that break." We therefore abandoned tilting, but I see now that was a lot different than the situations campers face.

I'm still new to camping with solar-- a completely different league than the little 12" panels we worked with! I still think, however, I'd stay away from reflectors. Thanks for the very informative video!

As a point of interest, here's a couple photos of one of our fastest cars ever. Covered the 20 meters in 5.5 seconds, designed and built by a team of 8th grade girls back in 1996. 

Mr_Mrs_Gnome

Would probably be tough to experiment with and without a reflector, given that no two days are exactly the same. I would think that if you are adding light to the panel, you would increase the output. It would depend on also having the reflector at the correct angles to reflect light onto the cells, not just randomly into the air. It would be like the heliostats (mirrors) pointing light onto the solar towers at the Ivanpah Solar Facility near the CA-NV border on I-15.

jkjenn

Mr_Mrs_Gnome said:

Would probably be tough to experiment with and without a reflector, given that no two days are exactly the same. I would think that if you are adding light to the panel, you would increase the output. It would depend on also having the reflector at the correct angles to reflect light onto the cells, not just randomly into the air. It would be like the heliostats (mirrors) pointing light onto the solar towers at the Ivanpah Solar Facility near the CA-NV border on I-15.

I think to really have a good grasp of there performance differentiators would be to use one of those meters designed to get a reading on solar panel performance.

Photomom

I don't think the reflector will work at all. I think the sun's rays will strike the reflector, and most of them will bounce off at a 90 degree angle, missing the solar panel entirely. That is assuming that the solar panel is oriented to face the sun directly.

On the other hand, someone who already has a solar panel with a controller that indicates power produced can check this in a couple minutes with a piece of aluminum foil!

Nomad

Photomom - Late afternoon / early morning when the angle is shallower they may hit - Still doesn't seem worth the hassel though.

Photomom

Oh come on! I was hoping you'd run a test. After all, it's just a piece of tin foil :-) According to my calculations, though, as long as the solar panel is oriented facing directly towards the sun such that the sun's rays hit it perpendicularly, the reflector won't make any difference. I double dog dare you to prove me wrong.

Nomad

My solar works just fine without so was just curious - not curious enough to waste foil though...I need my foil for a hobo dinner :-)
Watched a guy moving his panels and reflector around all day today.

Ratkity

Hobo dinner lol - we used to call it "pocket stew". Ours was hamburger, use a potato peeler for taters, carrots (if you like them things), cut onion strips, some bread crumbs, a squirt of ketsup, a little salt and pepper - seal foil over top and roll ends - cool for 35-45 min in fire (depending on how big your "stew" was).

Solar.. um.. yeah.. I bet you could cook that in a reflector (solar) oven! (phew! stayed on topic... barely).

Nomad

Miraculous on topic recovery there Ratkity :-)