Hi.
I'm Amy Beaudet from the altE Store.
Thank you for watching our video series, we've broken it down into multiple parts to keep
it manageable.
This video is called "Solar Electric Components, Racking".
If you missed our previous videos, I recommend you go back and watch the earlier ones in
the series to get a good foundation, including part 1 covering solar panels and batteries,
and part 2 covering charge controllers and inverters.
Racking is a less glamorous, yet critical component to a solar system.
We'll briefly go over three of the most common types of racking; roof, ground, and trackers.
So let's get into some racking options.
The first place people think about installing solar is on the roof.
There are options for installing on all types of roofs; including asphalt or tile shingles,
metal standing seam, and flat rubber roofs.
Any roof penetrations, including bolts for the mounting feet or the conduit going through
the roof, must be flashed to prevent leaks.
There are several good options available depending on the type of shingle, but we are not going
to get into them for this video.
When selecting a roof mount, you do have the option of using legs to tilt the angle of
the panels higher or in a different direction if needed, but it is generally recommended
that you just mount the panels flush on the roof, and accept that it may not produce as
much power as it would if at the idea angle.
Unless you have to squeeze out every last bit of power from the array, generally, a
flush mount looks better, and you don't have to be concerned with additional wind loading
by being raised off the roof.
Standing steam metal roofs need a solution that won't drill through the metal.
Clamps are available to grab onto the standing seam, allowing you to connect the rails, or
the panels themselves, right to the clamp.
Likewise, you don't want to drill through a flat rubber roof.
A ballast mount allows you to weigh down the racking with concrete blocks instead of bolting
them to the roof.
Ballast mounts are generally tilted at a lower angle than a traditional roof mount, as it
tries to reduce the wind loading that could potentially move the array, since it is not
bolted to the roof.
There are a lot of options for mounting the array on the ground.
Smaller arrays can be mounted on the side of the pole, larger ones, up to 18 modules
or more, depending on the panel size, can be mounted on the top of a pole.
Pole mounts and some ground mounts provide an adjustable option, allowing you to optimize
the angle of the panels to match the seasonal angle of the sun.
Ground mounts give you options for very large systems, provided you have the space for them.
Carports provide shelter for your vehicle, while providing you power.
An awning mount on the side of your house can sometimes be an option when no horizontal
location is free.
As you can see, there are many options available, not just on your roof.
Trackers will automatically follow the sun throughout the day from east to west, and
optionally change the tilt throughout the year as well.
A passive tracker generally has canisters with a gas inside, which changes weight as
they heat up and cool down.
This causes the array to gradually move from east to west during the day, returning to
east by morning.
This requires no electricity to track the sun throughout the day.
Active trackers have an electric motor that follows the sun east to west throughout the
day.
It can also adjust the tilt seasonally.
Active trackers are usually more expensive than passive trackers.
Depending on your location, a tracker can increase your output by as much as 30%.
But they also add complications to the system, adding a mechanical component that could potentially
fail.
It's often less money and less work to simply add 30% more panels to your fixed system to
increase the output.
To help decide which racking is right for your system, let's talk about performance
based on the angle of the array.
For best output, you want the sun's rays to hit the array at a 90 degree angle.
To figure out the angle you should mount your system, know that generally, for a fixed mount,
which is one that doesn't get adjusted seasonally, the best tilt is equal to your latitude.
Here in Massachusetts, we are at 42 degrees latitude, so the best angle to tilt your system
is 42 degrees off horizontal.
If you have a system that you want to optimize for Winter output, squeezing every bit you
can out of the short day, you would tilt it an additional 15 degrees, at 57 degrees here,
to keep the panels pointing at the low winter sun.
Since the sun is higher in the summer, if you have a seasonal cabin that is only used
in the summer, you would tilt the panels 15 degrees higher than latitude, or 27 degrees,
here in Massachusetts.
"Sun hours" uses a compilation of historical weather data to determine the amount of solar
energy available at the solar array, based on Standard Test Conditions.
Although the sun is shining for 12 hours, the intensity of the sun isn't the same for
all of those hours.
For instance, the sun is half as intense at 8:00AM as it is at 11:00AM, so from 8-9 would
count as half as many sun hours as from 11 - 12.
This chart shows the sun hours of 2 extremes here, Anchorage Alaska and Key West Florida,
for an array that is fixed, or doesn't move, and at different angles in relation to the
latitude, vs a tracker, one that automatically follows the sun throughout the day, set at
different tilt angles or one that automatically changes the tilt throughout the year.
It shows the sun hours per month, as well as an annual average.
This is very useful to determine the amount of electricity output you can expect for your
area, depending on how you rack the array.
You can decide if it is worth the extra money and effort to change the angle of the array
seasonally, or if it makes more sense to just set it and forget it, and size the array based
on that angle.
For example, you can see that in Key West, setting a fixed array at latitude gives you
an annual average of 5.5 Sun hours.
A single axis tracker also set at latitude would increase that by almost 30% to 7 sun
hours, but going up to a dual axis tracker that also changes the tilt seasonally, only
adds another .2 sun hours on top of that, so it may not be worth it to you.
As you can tell, there are so many racking options available to choose from.
Check out our website for a great selection of racking and trackers available.
lso watch more of our Video Series on our web site to learn more about solar.
e've got a team of highly trained Technical Sales Reps available to help you plan your
system, give us a call, we'd love to help.
And don't forget to check out the rest of our site at altestore.com, where we are making
renewable, doable.