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Hello, everyone and welcome to another edition of Tech Talk Tuesday. Hi, this is
Amy Hoagberg coming to you from Blue Oak Energy in Davis, California. I wanted to talk with
you today about optimizing tilt angle for modules in constrained spaces. We'll start
first with the graph that we have up on the left here. In most cases, we are looking to
optimize the amount of energy that we can get out of a rooftop or maybe another constrained
space. Given the choice, if we were at the equator, those modules would be perpendicular
to the sun. That's where we're going to get the most amount of energy out of those modules.
In the northern latitudes, however, we've got that sunlight coming into us at an angle,
and so we want to tilt that module toward the sun. In many cases, it would be the latitude
of your site that is equivalent to the tilt that you want to give to that module. Let's
look at the next graph down here. We see that, let's say for Davis, California, very near
Sacramento, we would start off with a module tilt of 30 degrees. We would then space the
next module behind it in order to prevent shading from the first and so on and so on.
We'd be building up our array on the rooftop mainly to try to reduce shading during the
winter solstice and then knowing that everything else beyond that point during the year is
of a higher energy. Let's say you want to try to pack more modules into that rooftop.
You know that you've got mechanical units and rooftop units that are taking up space.
You've got vents that are taking up space. Let's look to see what would happen if we
had those modules at a different tilt. It's basically a cosine function. If you look at
the amount of energy that you would get from a module, which has a zero degree difference
or theta between perpendicular and its normal, we would see you get about 100% of that energy.
If you drop that tilt or change that tilt about 10 degrees from normal, you still have
about 98.5% of that energy. If you continue to drop or take the perpendicular away from
the module, you now can continue to drop that energy, but it's really not that much. You
may have some energy lost due to reflection or to internal optical losses in the module,
but overall it brings advantage to do that. If we come down to this graphic here, we can
see that if you drop the module tilt, again for an area like Davis, California, you can
now pack those modules in. You can physically move them closer together. When you're able
to do that, instead of taking up all the space on your roof for shading, you now have more
energy that's being produced. It varies greatly depending upon the roof surface, how many
obstructions are there, etc. In general, you may be able to see an increased power density
of about 10% to 20%. In terms of your yield, kilowatt hours per kilowatt peak, you might
see an increase of about 5% to 15%. So I hope this lesson has been valuable for you. Thanks
again for tuning in for another edition of Tech Talk Tuesday, and have a great day. hB]f
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