Reflectors?

[Scott Loupin]

I find that the sun rises behind my panel array, so I'm missing an hour of
daylight. Has anyone ever set up large reflector panels to beam the sun
onto their panels? I'd envision it NOT reflecting sunlight once the sun
moved around enough to face the array.

Economics doesn't matter, I have access to sheet metal. Would I actually
gain any energy?

Thanks,

Scott

 

[Gym@Bob]

Moving the panels would be the best option.
You mayonly get a few minutes of reflection out of it and your best period
still isn't captured. The reflector may put your panels in the shade later
in the day.

 

[Scott Loupin]

Hi gymbob;
I might have to move them, I'm on a steep hill, and it cuts off sunlight in
mid-afternoon. Maybe I should re-orient the panels to point between sunrise
and 'sunset'?

Thanks,
Scott

 

[Gym@Bob]

I have been told that 12 noon sun is the best pointing angle for max output.

Can you raise the height of them to avoid shadows?

Mine point at about 11:30 Sun and the power curve is gone about 2:30-3 PM
each day right now anyway. Now this is with the static angle I am using on
this set. Most of the power I get starts about 9-9:30 AM

 

[[email protected]]

I have been told that 12 noon sun is the best pointing angle for max output.

Wrong again. Sounds like you've been listening to George.

Nick

 

[Gym@Bob]

Well then what is it?

output.

Wrong again. Sounds like you've been listening to George.

Nick

 

[Gym@Bob]

Funny thing is I and another person recently started threads on the best
angle of solar panels, After all the self-proclaimed experts here were done
flaming, stamping their feet, pounding their fists, and acting like two year
olds, none of them produced an answer. If George had an answer then it was
the only one provided.

BTW: who the **** are you to tell me I wasn't told that? You need to try
reading more carefully perhaps?
Maybe instead of just trolling like a jerk you could try to produce saome
real information for once. My bozo bin is getting rather large with all the
swollen heads here in it.

 

[Gym Bob]

Thanx for a real reply SG. People here need to see it can be done.

 

[wmbjk]

BTW: who the **** are you to tell me I wasn't told that? You need to try
reading more carefully perhaps?
Maybe instead of just trolling like a jerk you could try to produce saome
real information for once. My bozo bin is getting rather large with all the
swollen heads here in it.

Oh yeah, people are going to be tripping over each other trying to
help somebody with your attitude. Perhaps you could compare your own
contributions with Nick's http://www.ece.villanova.edu/~nick/usenet/.
Of course that's sort of like asking Mr. Magoo to compare his eyesight
to the VLT. BTW, your "bozo bin" includes a whole bunch of the people
who could answer every question you could think of... if you weren't
such a jackass.

Wayne

 

[Gym Bob]

OT for this thread...sorry.

SG. I have been viewing your first installation pics and have a question.

The back support pylons for your array appear back too far. Was this done
because the desired angle was not known at the time or other resons.? It
appears, knowing what you know now, the back leg could have been verticle
and saved total footprint.

comment?

 

[Gym Bob]

Back in the bozo bin you morphing dingus.

When you get a clue you can call yourself a teenager maybe.

<PLONK>

 

[Scott Loupin]

I can't raise the panels enough to avoid the shadows caused by the trees on
the hill behind me. And the trees are on my neighbor's property, so no
chance of cutting them down.

Scott

 

[Windsun]

Actually, in most places the best overall angle is around 30 minutes after
solar noon, due to the presense of morning haze in most places. However, the
fact is, if you are pointed due south vs about 10 degrees either way, the
difference in power production is less than a 5% difference. Most panels
produce 90% of their power between around 10 am and 3 pm - an hour more each
way in summer.

Also, don't forget that compass south can vary from true south by as much as
20 degrees. Do a Google search on "magnetic declination" - lots of places
have charts.

The drop off in power vs angle is a function of the cosine of the angle. So
at 10 degrees sun angle you lose around 1.5%. At 30 degrees you lose 13.4%,
at 45% you lose 30%. The 50% power loss point is 60 degrees. That is the
theoretical maximum - in actual fact at high angles it can drop off a bit
more because many panels have glass and/or cell surface "texturing" -
basically microscopic pyramids - to minimize reflection, and past 45 degrees
or so that loses some effectiveness.

 

[Gîmmìe Bob]

Check this out. This can be real helpful with a little study

http://solardat.uoregon.edu/SunChartProgram.html

Careful of the parameters, especially the time reporting.

 

[[email protected]]

Actually, in most places the best overall angle is around 30 minutes
after solar noon, due to the presense of morning haze in most places.
However... if you are pointed due south vs about 10 degrees either way,
the difference in power production is less than a 5% difference.

Now I'm not sure I understood the original question. When Gym* said
he heard the answer was "noon," I thought back to George Ghio's claim
that on a particular day, a fixed panel aimed south with an elevation
aimed at the noon sun would produce the most energy over that day.

George was wrong, of course, in the sense that a panel like that would
produce the highest instantaneous power at noon on that day, if it's
perfectly clear, when the cosine of the incidence angle is zero, but
a panel aimed closer to the horizon would likely produce more energy
over that day, with less power at noon and more at other times. Then
again, noon sun is brighter than morning and evening sun, on average,
since it travels through less air. And over a perfectly overcast
isotropic-sky day, a horizontal panel would produce the most energy.

But now it appears the question concerned azimuth vs elevation...

The drop off in power vs angle is a function of the cosine of the angle.

The power is proportional to the cosine of the solar incidence angle, ie
the angle between the sun and a perpendicular ray from the panel, which
depends on elevation as well as azimuth. That's close to the cosine of
the azimuth angle for small azimuth changes, but not exactly proportional
to the cosine of the azimuth angle.

So at 10 degrees sun angle you lose around 1.5%. At 30 degrees you lose
13.4%, at 45% you lose 30%. The 50% power loss point is 60 degrees...

Cos(60) = 0.5. This works if the sun has the same elevation all day
It might also work if we assume the panels change their fixed elevation
as they change their fixed azimuth. Max-energy East- and West-facing
panels would be closer to vertical.

Nick

 

[Gìmmìe Bob]

Ah heck, get a dual axis tracker for your NiCad AA cell charger.

 

[daestrom]

Back in the bozo bin you morphing dingus.

When you get a clue you can call yourself a teenager maybe.

<PLONK>

You know, wayne and the others aren't the ones that are morphing. You've
changed your name yet again (you are easy to recognize after just a couple
of posts even if your name wasn't obvious).

Maybe if you quite morphing, your kill files wouldn't get screwed up and you
wouldn't have to keep "<PLONK>" 'ing people all the time.

daestrom

 

[Gìmmìe Bob]

ahh nice.

In the summer position , the array is at 4 degrees and the rails lay flat on
the rear supports. The racks are 4 season adjustable , 4, 28 , 54 degree
notches on the two support rails , only takes a few seconds to adjust a rack
, just loosen two wing nuts , change the tilt and re-tighten the nuts

www.solar-guppy.com/arraysummer.jpg is the array flat on its back ...

 

[Gìmmìe Bob]

Some of them are morphing. I have several listings for some of them in my
killfile.

It wouldn't matter, they are mostly children with attitudes. Nobody needs
that kind of help. They can't seem to supply any help anyway.

Thanx for the try though.

 

[Windsun]

True that you really have to figure both angles, but assuming that the panel
is aimed at the sun perfectly at solar noon for both angles, plus or minus 3
hours it makes little difference. It is when you get outside that range that
the two angles start to add up. But since you usually get 90% of your power
plus/minus 3 hours from solar noon anyway, the overall daily production is
not affected as much as you might think.

Wattsun makes a dual axis tracker, but if you look at the figures from NREL
for 2-axis trackers vs single, they have not really been cost effective
since panels dropped below $8 a watt or so. The net gain in 2 vs 1 axis is
not all that much compared to the expense of doing it. Simply adjusting your
panel manually 2 or 4 times a year will give you almost the same gain.
[/QUOTE]