What effect does tilt angle have on solar panels?

HI this is Amy from the altE Store. We've
shown you videos already on the effect of shading on solar panels, and effect of the direction
you point your panels, now we are going to show you the effect of tilting your panels.
Now the angle that you select to mount your panels will depend on a few different things.
If you have got just a straight grid tie system that is going to be on your roof and your
roof it a normal average tilted roof, you're really just going to put it on that, because
chasing after every little last angle on a grid tie system quite often isn't worth
the extra money. But, if you've got an off-grid system, and you need to pull out every single
watt hour you can out of the system, then angle really does come into play, quite significantly.
So I'm going to show you the effect of what we've got here. So it is November 20, very
close to the winter equinox, so the sun is very low in the sky.

I'm in Massachusetts,
so my angle up here, my latitude is 42 degrees. So if I want to maximize year round performance,
I would want to set my panels at as close as possible to 42 degrees, because if you
figure it's going to be that, the sun is going to be that angle in the spring and the fall,
as opposed to in the summer when it's just going to be really high, or in the winter
when it's going to be very low. So you really need to figure out when you will be maximizing
it. Do you have a winter hunting cabin that you need to maximize your winter, or a year
round place, in that case, you'd want to put them at bit of a steeper angle to try to get
as much power as you can during the short winter days. If you just have a summer camp,
you're going to have it really up very high.

If you've got an RV that you are just driving
around with, odds are pretty good that if you just put it flat on the top of your roof,
you're going to be great, because you are probably going to be using it in the summer
when the sun is the highest. So let's actually see what affect this has. Now again, I'm at
42 degrees latitude in November, so I've got this at just over 50 degree angle. So I'm
really pointing directly at the sun.

Now you see up here, I've also got a meter, it's an
insolation meter, so it's showing me the intensity of the sun. Solar panels are rated at the
standard test conditions, which is 1000 watts per square meter. So right now at quarter
of two in the afternoon, I'm almost at 900 watts per square meter. So I've got pretty
good intense sunlight right now. And so I'm going to show you the volts and the amps.
So my volts right now is 19.8 volts and my amps is .41 amps. So you know I've got little
5 watt panels, so they are going to be fairly low.

But you are going to see a pretty dramatic
change here in the amps, but not so much on the volts. If you saw the other videos you'll
see that intensity of the sunlight doesn't affect volts as much as it affects amps, and
that's true with most semiconductors. So I'm going to change my angle here. So I've got
it at 35 degrees now. My insolation has dropped down to 712, by volts is still pretty high
at 19.6, but my amps have dropped down to .34. Now if I go down a bit more here, now
I'm at 20 degrees, which would be great in the summer, but November 20? Not so good.
My insolation's down to 500 and something, 540, my volts is still, again, still fine
at 19.4 volts, but my amps has dropped almost in half to .27 amps. If I drop down even further,
so I'm pretty much flat, so this is something you'd see probably on an RV, my insolation
is dropped down to 267 watts per square meter.

My volts is still ok, it's 18.8 volts, but
my amps is .15 amps, so I'm really not getting much power out of these panel. So you really
can see that the angle that you tilt them does matter. So if you've got an off grid
system, you might want to do something that you can have them adjustable angles, so that
you can have it so that in the winter you are going to have it pretty steep, and in
the summer you are going to have it pretty shallow. Now again, if you've got a grid tie
system, quite often it isn't worth it because the year round average is going to average
out to be alright.

But if you have got an off grid system where you really need to keep
those batteries charged up in the winter, having an adjustable system is a great idea.
We can actually combine a couple of these demos that we did and if you have a tracking
system, a dual axis tracking system that will actually follow the sun during the day , and
change its angle throughout the year, that gives you the best of both worlds. So that
would really greatly increase your output, but does add a lot of expense and mechanical
capabilities to your system. So it is something you really need to take a look at, does it
make sense to be chasing after every little bit, could you just make up for the less than
perfect conditions by putting some more solar panels on. So that's a bit of a balance. So
I hope this helped you understand what angle does.

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