[RE-wrenches] solar roof lift experience?

Matt Lafferty gilligan06 at gmail.com
Wed Aug 12 13:45:28 PDT 2009


Roof-Wrenches,

You might look into getting a roofer's lift-bed truck. This isn't a panacea,
but it's great on most resi applications where you can get close to the
building. If you're a real slave driver, you can put a porta-john on the bed
and make sure your roof-crew never gets off the roof until it's time to go
home! For commercial scale rooftops, you're gonna need to buy or rent an
extended-reach forklift (Gradeall, Lull, Gehl, whatever). Weight capacity &
boom length dependent on project.

If a lift-bed truck isn't in the cards and it's not a low, single-story
roof, I always use a crane. The professional kind. As in, you schedule them
to meet you at the job, they show up, lift your gear, and leave. $100-300
depending on the size of the crane, time on job, and distance to job. Make
friends with your local crane company(ies). Find out who the HVAC guys use
to lift their equipment and go talk to them. That's the outfit you want. You
will need to talk with them to find out their pricing and setup
limitations... Slopes, clearances, boom lengths & angles vs. capacity, etc.
(PV is way lighter than package HVAC units) You will need to make sure your
site survey and price includes consideration for the crane. Not a big deal.

The way I see it, the reduced fatigue is worth a whole lot of extra
productivity later in the day. It also cuts down deployments per project
since your total "truck to roof" time is cut to 20 minutes or less in most
cases. Less chance of damage to modules. Reduces trips across roof which
minimizes wear and tear on the roof. The most undervalued savings is in
safety. Transporting modules and equipment to the roof is arguably one of
the most dangerous parts of the job. Any time you can minimize risk and gain
extra benefits, it's a no-brainer. Just do it!

If you pre-panelize in the shop, then use glazer's lifting suction cups to
fly 3 or 4-module panels one at a time. McMaster-Carr Part #53615A13.
Catalog page 1458. http://www.mcmaster.com/#suction-cups/=35r4ht  You need
to buy 5 lifting cups for each crew. 4 to use for lifting each panel. The
5th is your backup. Fly each panel straight into place on your standoffs.
Two guys on the roof bolt 'er down while the crane is swinging back to get
the next one. The guy on the truck does the stick and go. Average about 2 to
2-1/2 minutes per cycle. If you're flying glass to the blind side of the
roof, you will need a signal guy at the ridge to guide the operator. The
truck/ground guy can climb up and do this job if need be. Once you've done
it this way, you'll never go back to 1-module at a time. This method saves a
bunch of broken tiles on tile jobs compared to walking all over carrying
extra weight. (Note about the suction cups: Always buy the spare suction
cup! The one time a cup failed we were glad to have the spare! Make sure
your guys don't "pound" the piston with the side of their fist to pump the
cup! There is a plastic rod inside that doesn't like being pounded on.) 

If you install the traditional way, 1 module at a time, you'll need to build
some "ridge-tables" to land stacks of stuff on. If you're organized, two
guys can have 4kW of racking and modules on the roof in 5 minutes. 3 lifts.
Safely. Ridge-table is the name I gave to the platforms I built for this
purpose. Basically, they are heavy-duty tables that span the ridge with
adjustable, fold-out legs on either end. The legs have a cross-member that
sits on the roof surface and spans at least two rafters/trusses/joists. You
will need to strategically place the tables so they aren't in your way while
you're installing. Same principle as "not painting yourself into a corner".
I built my originals out of wood. They were heavy and bulky, but they were
reliable and we installed thousands of modules using them. (Before moving to
pre-panelization) If anybody wants a sketch, give me a holler off-list.
(Note: May or may not be compatible with your metal roof. Must remove
section of tile where cross-member sits on roof for tile jobs)

Funny thing about using cranes... People don't think of them for PV. I come
from the HVAC industry originally. Flying equipment with cranes, and
sometimes choppers, was normal to me. Been doing it since I was a kid. Bob-O
thinks I'm still a kid, but that's another topic. ;) When I stumbled into
this solar gig, I worked for Dave Metcalf @ UPG. He thought I was crazy to
want to use a crane. Couldn't imagine it being a money-saver. Had to see it
for himself. I called up the crane company I'd used for 15 years. They
showed up, lifted 5 pallets of glass in less than 10 minutes and left. Dave
was pretty much sold from that point on. (For those of you who remember,
this was the project with the Bell-box cover screw that pierced the wire nut
and took so long to find. Use your Megger or megger-like device! "Megger is
a registered trademark...")

When we got to the point where we were switching to more conventional
modules, we wanted to pre-panelize. We had the roofer's lift-truck by then,
but knew from experience that the benefits of using a crane outweighed
dragging 200# panels very far across a roof. If we could backup close to the
array location, then we would hand-carry, of course. This is when the
suction cups came in. I knew about them from working with a friend doing
skylight work. I looked at it this way, What are we dealing with? Big pieces
of glass. What do glass guys use? These suction cups. 

They worked like a charm. Gives your guys a safe way to handle and position
panels as well as lifting attachment points. When I moved over to working
"at" SMUD, instead of "for" SMUD, I had to train and manage installation
contractors. When we did the training, I had my crane company of choice come
out. The contractors were skeptical... Until they actually did it. Changed
their lives. Flying glass. It's the only way to go!

A couple years ago, one of my crews had only done pre-panelized jobs for 3
or 4 years. Then we had a job where it had to be stick-built... Lead-guy
threatened to quit if he ever had to do another one like that. The whole
crew moaned and groaned. I told them that's how most "solar installers" do
it every day and that they should be grateful. They didn't see how anybody
would ever do it that way on purpose when pre-panelization is so smooth. One
thing they all mentioned was how difficult it is to police the wiring
beneath the array very well. They were used to having everything all tidied
up and ready to go when it lands on the roof. 4 bolts, 2 MC connectors, and
1 or 2 grounding jumper connections per 4-module panel.

If you are using 3 or more installers on a job and you have some shop or
secure yard space, you should look at doing pre-panelization when you can.
I'd be happy to outline the design, logistics, and installation
considerations for anybody that wants to take a look at this methodology. In
general, it is best applied when you are using the same type of modules and
racking over and over. Your own "kit" if you will. At least in the
beginning. This gives your team (survey, design, installation) the chance to
streamline the process. Once you've got the key pieces worked out, applying
the process to a different module type isn't a big deal.

Happy lifting!

Matt Lafferty




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