Tips for Squaring Up Parallel Standoff Array

SolarEpiphany

Hey There,

Any tips from the experienced elders of the solar community on squaring up an array? It tough (as you know) to find anything square to measure off of on a roof. How have you tackled this challenge in the past?

Thanks in advance,

Windsun

Re: Tips for Squaring Up Parallel Standoff Array

http://home.howstuffworks.com/chalk-line.htm

Laser thingies don't usually work well on roofs, too bright to see the line.

niel

Re: Tips for Squaring Up Parallel Standoff Array

i'm not sure if i am following what it is you are after, but if for example you have a square and pushed it like it might be a house getting ready to fall down, like this but connected <>, you would still have equal lengths in the sides even though the angles have shifted off of 90 degrees. the degrees aren't easily measured or obvious, but measuring diagonally from opposite corners would show if it is not squared as a perfect square will show those diagonal lengths to be equal to each other. this works for rectangular as well as box arrangements.
does that help?

tallgirl

Re: Tips for Squaring Up Parallel Standoff Array

Windsun wrote: »

http://home.howstuffworks.com/chalk-line.htm

Laser thingies don't usually work well on roofs, too bright to see the line.

Work at night

That way it's cooler and you can see the laser better.

Cariboocoot

Re: Tips for Squaring Up Parallel Standoff Array

Do you mean squaring the array itself (as in getting the mount square so it can be changed in angle without binding) or squaring it to the roof for aesthetic/space reasons or squaring it to the compass for alignment?

Framework can be squared by measuring diagonally across both directions on the assembled frame: equal diagonals means it's square.

Roofs are quite another problem, as try as you might it's nearly impossible to get a roof perfectly square/level. You can check the diagonals and see how square it is, then measure equidistant off the ridge, eaves, and ends to determine location. Snapping chalk lines can give you a viable grid and it will wash off in a rain or two.

For compass squaring what you need to find is level. Chances are the roof isn't. But a theoretical plane across the top and bottom of the panels should be. If this is perpendicular to the angle of rise then it can be aligned with the sun.

Yeah, it's a lot of gobbledegook, math, work, bleah ...

The good news is it doesn't have to be perfect to work. None of us are/do!

SolarEpiphany

Re: Tips for Squaring Up Parallel Standoff Array

I'm looking for techniques to square the array. For example; how do you all square the first module in the array; the one you build off of. Are you eyeballing it?; using a row of shingles as a line?; snapping chalk lines (what are you measuring from- a "i hope this is right" place on the ridge or an "I hope the roof is straight" eave? Do you see what i'm getting at? THe roofing material causes irregularites, the roofing construction causes irregularities. If the first module is off, the whole array will be tough to tie together.

Also, what about leveling the array? Any tips or tricks from folks that do it a lot? I've seen a piece of angle iron with a magnetic laser used, but I don't quite understand how.

Thanks folks,

niel

Re: Tips for Squaring Up Parallel Standoff Array

use chalk lines and think in terms of vinyl floor squares.

dwh

Re: Tips for Squaring Up Parallel Standoff Array

Figure out where you want it; 1' down from the ridge? 2' up from the eave? Whatever.

Say you want it 12" down from the ridge and 9" up from the eave. But when you measure it out, you see that it's not perfect. Maybe if you stick to 12" down from the ridge, you will end up 9" from the eave at one end, and 7 1/2" from the eve on the other end.

Eyeball it. Will that make it look goofy? Maybe so. Maybe it'll look better if you average it out. So at one end you are 12" from the ridge and 9" from the eave, and at the other end you split the difference and are 11 1/4" from the ridge and 8 1/4" from the eave.

Okay, say that looks good. Now snap your chalk lines to those points.

The thing is, buildings aren't perfect. I've seen some where I could tell that the guy who built it didn't even own a level.

So you work with what you've got - nudge it here and average it there until it both works AND looks halfway decent, then go with it.

SolarEpiphany

Re: Tips for Squaring Up Parallel Standoff Array

Right on. "Just do it" seems to be the M.O. We just installed a 4.2kw system and had some challenges in this area. That's why I'm asking. Its probably just a confidence thing that we'll aquire after more installs. The array looks great, it just took awhile to layout.

Take care,

dwh

Re: Tips for Squaring Up Parallel Standoff Array

SolarEpiphany wrote: »

The array looks great, it just took awhile to layout.

Take care,

That's exactly as it should be.

When I do a job (electrical - I haven't done any solar installs) I take as long as I need to lay it out, and I don't let anyone rush me either - which has pissed off more than one general contractor. I'll measure, eyeball, stare at the plans...eyeball from a different angle...measure and stare at the plans again, go back and eyeball again.

Man, I *HATE* having to do things over because I boned up the layout.

Kamala

Re: Tips for Squaring Up Parallel Standoff Array

If the area is roughly rectangular, you could snap chalk lines from diagonally opposed corners. This makes an X on the roof. Find shortest of the 4 arms of this X as measured from it's center. Measure the same distance from the center of the X down the remaining 4 arms and the resulting square should be nearly true. A length of string used as a compass simplifies this procedure. You could also offset the initial measurement of the shortest arm to "shrink" the square.

Tried a simple test in CAD and it seems to work if only one corner is not square. It won't work if all four corners are untrue.

Otherwise, using the snapped X, couldn't you use a level to construct a true horizontal from the center of the X? I'm no carpenter but maybe these ideas will start some others thinking. I also imagining ways to plumb a vertical from the center point. FWIW.

Craig

Cariboocoot

Re: Tips for Squaring Up Parallel Standoff Array

Don't forget the "3-4-5" rule, also known as the Pythagorean Theorem, very handy in construction:

A squared + B squared = C squared. If one leg of a right triangle is 3 and the other is 4 then the hypotenuse is 5.
Measuring 3 feet (or multiple thereof) from a point in one direction and 4 feet (*X) roughly perpendicular from it should give you two point 5 feet (*X) apart. If you this along a roof ridge or eave against the side you can tell how square the corner is.

Kamala

Re: Tips for Squaring Up Parallel Standoff Array

Cariboocoot wrote: »

Measuring 3 feet (or multiple thereof) from a point in one direction...

TWISI, this direction (along with it's perpendicular) needs to be level and/or plumb. The method of determining the "trueness" of a rectangle by measuring the length of diagonals is a way to employ the Pythagorean Theorem without doing the math.

The problem here is that the reference, or right angle, is unreliable. That being any given corner of the roof. The problem then is to try to reconstruct a reliable (true will not be possible) right angle on the rooftop. Once this is done, the "grid" can be laid out.

C

Cariboocoot

Re: Tips for Squaring Up Parallel Standoff Array

Kamala wrote: »

TWISI, this direction (along with it's perpendicular) needs to be level and/or plumb. The method of determining the "trueness" of a rectangle by measuring the length of diagonals is a way to employ the Pythagorean Theorem without doing the math.

The problem here is that the reference, or right angle, is unreliable. That being any given corner of the roof. The problem then is to try to reconstruct a reliable (true will not be possible) right angle on the rooftop. Once this is done, the "grid" can be laid out.

C

Er, no Craig; in this instance you're "checking it against itself" - determining if the ridge or eave is at a right angle to the side. It is that corner that you're trying to find out if it's square. Chances are pretty good it isn't, though.

Kamala

Re: Tips for Squaring Up Parallel Standoff Array

Cariboocoot wrote: »

you're "checking it against itself":p

Rather, this is exactly what I am trying to account for. If you wish, you may PM me so that this thread is not to drastically hijacked.

solarix

Re: Tips for Squaring Up Parallel Standoff Array

I know what you mean. I've got some machinist in my background and I am a little nuts about getting things perfect, but have to admit it can be tough to do so on a roof. Can't trust the shingle or tile lines. Very hard to get your mounting rails straight. Method I use now is to not worry about the rails since the panels are adjustable with top mounts. Put the first panel on by eyeball, but keep it just snug. Add several more panels till you have enough to prove the layout is good then juggle and adjust them for best look. If you have four panels with a common corner lining up and are parallel to the roof, you should be good to go.

dagr51

Re: Tips for Squaring Up Parallel Standoff Array

Use white chalk in your chalkbox. Red will be there awhile.

newenergy

Re: Tips for Squaring Up Parallel Standoff Array

As mentioned the various lines on the roof will not be truly parallel or perpendicular. You need to decide from eyeballing and looking from the ground what line you are going to want to be parallel to.

I chalk line based on that for where to put the standoffs. Then I make sure the rails are straight. It's easy to adjust the rails and get them just the way you want them. Then I set the modules based on the rails. For the first (most important) modules, I take a lot of time. I use a square vs. the rail, a measuring tape, and I take a string and run it along the bottom of the module and extend it a long way past the module. I can generally tell if the module is lined up well from this string. The rest of the modules set in tight. After 3 or 4 modules you can tell if you screwed up and adjust it. You can make some tiny little adjustments to fix it later on, but they have to be very small because the clips won't fit well otherwise and small adjustments on one row become bigger problems on subsequent rows.

I'm trying to do more installs with the Unirac SunFrame system. You have to be more precise with the standoffs, but when you get the rails right, the modules will definitely be right. It also lets you bring a ton of modules up on the roof at a time w/o having problems with where to set them.