Solar: The Build Begins

The posts are in!

It's Wednesday and I'm just now recovering to the point that I can type this out without my shoulders aching.  J. and I may have overdone it a little this Memorial Day weekend.  But, hey, I wasn't going to let a 3-day weekend go by without working on the solar project.  We started the actual build!

 

Our poor little Dingo gave up the ghost at the thought of all that hole-digging and heavy lifting and wouldn't start, so it's in the shop.  Isn't that always the case?  You need your machinery and it breaks down right when you need it.

 

So off we went to Beagles Rentals to rent a beefier skidsteer for a day.  It turned out to be a good idea, because we got done much faster than if we had tried to use the Dingo and it was heavy enough that we were also able to use it to square up the chicken coop a little bit and move that 600-lb tree that we need to plant.

 

First on Saturday's agenda was to try to get the lot a little more level where the panels are going.  The array is going to be 51' 4" long by 13' wide and the lot slopes from east to west, which is along the long length of the array.  In fact, it slopes about 3 feet over that distance.  There was no way we were going to get it totally level, but we used the skidsteer to take the high side down about a foot and move the dirt to the other side.  A foot over 53' isn't as bad.

 

The array takes 8 posts of Schedule 40 pipe that's 3" pipe (it's actually 3.5" outside) and 0.216 thickness.  Shipping on the 9 pipes that we needed would have been ridiculously expensive, so we sourced it locally from a company called Rieves-Wiedeman located just a stones throw from our house.  Total cost: $1,544.05 with free delivery.

 

Folks, this stuff is heavy!  It comes in 21 foot lengths that weigh about 140 pounds.  Fortunately, we were cutting each pipe in half or in thirds for this stage of the build.  Here's a diagram of where the posts are placed:

Everything is correct on here except for the 10' posts.  They're actually 10' 4".   To get the 25 degree tilt on the array, the north run of poles needed to be 3 1/2 feet taller than the south run.  Everything needed to go into a hole 42" deep.   Why 42"?  It has nothing to do with the frost line, which is around 32" here.  The footings are that deep because of the wind load on the array once the panels are in place.  Think of it was a giant windsail catching the wind once it's all put together.  Yikes!

 

Another question I've gotten is about how we determined the placement of the poles.  First, we knew from talking to the city permit folks that we had to be further back from the street than the house AND we needed to be at least 5 feet off the back property line with our neighbors.  When we bought the solar kit, it included a racking system from IronRidge.  IronRidge has a handy-dandy online calculator that will tell you all the correct spans for your location, wind speed, snow load, etc.  You just input how many panels, your location and the configuration for your panels and it spits out the details like so:

Click to biggify!

Figuring it all out is the easy part.  It's the digging, squaring, measuring, pipe cutting and setting 10' heavy posts that will kill you.  Of course, it didn't help that it was in the upper 80's and humid as all get out.  If it weren't for our neighbor, Dave, I think J. and I would have died right there in the backyard on Saturday night after only getting in 2 poles and the other 6 holes dug.  If you've ever worked until you didn't have an ounce of energy left in you to even walk in the house, you know what I mean. 

 

Dave, if you're reading this:  thanks for helping us!

 

On Sunday, we took another 7 hours to finish up the other poles.  If we hadn't been dead tired from the previous day, we probably would have gotten done in half the time.

You can really see the height difference in the posts in this picture.

Now we wait until the weekend to give the concrete time to setup before we put on the two west-to-east cross rails.  Each one is about 2 1/2 pipes threaded together, so they're going to weigh about 350 pounds when all is said and done. We're going to have to do it in stages and have some help.  Anybody know any big, burly strong men that will work for beer and pizza?

 

This post has been shared as part of this week's HomeAcre Hop.  Go check it out!