Solar Swing-Set

[bennelson]

A Solar-powered Swing-Set!?!?

Wow, Ben, you really are a crazy eco-nut, aren’t you!

OK, so the solar panel doesn’t actually power the swing… Rather, this entire project is a photo-voltaic ground mount, cleverly suburban camoflaged as a children’s backyard play-set.

You may remember that I has a good experience running solar PV to my electric motorcycle at the MREA Fair. That, in turn, lead me to purchase a solar panel from Helios, a local “Made in America” solar manufacturing company in Milwaukee, Wisconsin.

I quickly pointed the panel south and started charging my Citicar with it. However, it was on literally the quickest and cheapest ground-mount I could come up with. I simply bolted three pieces of aluminum channel to the back of the panel, and leaned it up against three stakes I pounded into the ground. Couldn’t be simpler! Of course it also couldn’t be any more ugly or flimsy either!

So, I started thinking about what it would take to build a REAL ground mount. Of course I would want something solid, maybe pressure treated 4×4 posts? Elevating it wouldn’t hurt either. A few feet at a minimum, to keep the snow off in winter, but even higher would be good to avoid shading at certain times of year. By then, I was thinking about how children’s outdoor play-sets are constructed. Many of those even have a roof. People mount solar on roofs all the time. Wait a minute…..

If I simply bought a used play-set, I could mount the solar panel right to the roof AND have a swing and slide for my little girl!

I hit Craigslist and started looking around. Wow, used play-sets cost WAY more than I thought they would. But I did find a few at lower cost, with the expectation that the buyer disassembles and removes it himself. I have tools, a pickup truck and a trailer, so what the heck!

My budget for the project was $150. Why? Because I got an argon gas welding tank for free, and I was able to sell that for $150. That’s why. I looked through Craigslist and found a play-set for $150, but that guy never called me back. Instead, I had to shoot for a $200 one. I had an extra $50 squirreled-away from selling some other junk, so I could still make it work.



I shanghi’d my father as my assistant, and we made the hour-long trek to go get the playset. The first thing I realized when I saw it was that it was about TWICE as large as it looked in the photo. Yipes, sure hope I had enough room in the truck.

We got to work disassembling the structure with a battery-operated impact wrench (I thought to ask the guy ahead of time what size bolts it used!) It was definately a two-man job, and by the time we finally had the whole thing apart, carried to the truck and trailer, and lashed down, it was dark. We were both tired and hungry, and it was now 8:30 on a Sunday night. Our stop for cheeseburgers on the way home was more than welcome.

I dropped my Dad off, and made it the rest of the way home in the dark and drizzle of rain, hoping to avoid hitting any deer.

The next day, I spent setting the whole thing back up in my yard. That meant moving everything else out of the way and laying out all the components as a real-world exploded diagram. How could this thing possibly have this many parts? And where was the Ikea manual that should have come with it?



I started laying it out and assembling the pieces, first doing things that I knew where they went. Like a crossword puzzle or sudoku, it gets easier as you go. Once some parts are filled in, it makes it easier to figure out where the others fit.

By the end of the day, I had most of the plays-set assembled, minus the roof.

Today, I leveled the entire structure on scrap blocks of wood, using a prybar, a 2×4, and my car jack. Once everything was more or less plumb, square, and level (I usually like to say “Pick Two!”) I was ready to put on the roofs.

Too bad I didn’t have anyone around to lend me a hand with it. About an hour later, a cut hand, a kink in my neck, and a minor bout of cursing, I had the roofs installed. A quick trip to the hardware store got me a few nuts and bolts that broke during the original disassembly or went missing while bouncing down the road Sunday night.

Wow, at this point, I pretty much had the whole thing together. The little girl liked the new swing, and especially the climbing wall.

Now I have to figure out how to mount the solar panel. My Dad (a remodeler by trade) stopped by, and we took a look at the uneven roof-line and the PV panel. After kicking around a few ideas for a bit, we came up with a game-plan of using the aluminum I already have bolted to the panel, adding some blocking to the roof of the play-set, and adding a couple of attachment points on the far side of the roof ridge.

But THAT’S for the next installment of this story. For now, I’m just happy that my little girl has a place to swing. But I’ll be even happier when I’m producing 400 watts.



Ever hear the term NIMBY? It means “Not In My Backyard”! It’s what most people say to a new coal or nuclear power plant. Guess I’m just the opposite. Give me some nice, clean, renewable energy, and I’ll say YES! IN MY BACKYARD for sure!

Keep charged up!~

-Ben

[where2]

Subscribed. Thanks for sharing the story Ben!

[Daox]

Very cool Ben. You always have interesting stories! Thanks for sharing.

[bennelson]

I'm trying to figure out the best way to mount the panel.

I don't have any fancy official mounting brackets, so here's a video on what I'm thinking.

Planning Solar PV to mount on Clubhouse - YouTube

[Daox]

Sounds pretty good to me. I am wondering why you want/need to run a ground from the aluminum frame?

[where2]

Originally Posted by Daox

Sounds pretty good to me. I am wondering why you want/need to run a ground from the aluminum frame?

Probably that nagging requirement of an Equipment Grounding Conductor mentioned in NEC 2011 690.43.

Mike Holt has a good video on YouTube on the subject. Search for "NEC 2011 Solar - Equipment Grounding 690.43"

[bennelson]

Hey, a quick question for all you guys who HAVE installed solar before;

What size wiring do I need? The panel maximum output is 8 point something amps. I figure that 14 ga is used all the time for home 15 amp circuits, and I already have some stranded red and stranded black in 14 ga, so I'm planning on using that.

Any reason to do anything OTHER than 14ga wires? (And no, I'm NOT planning on adding more solar panels to the roof of the swingset in the future.)

[iamgeo]

Do you have a write up solar powered power wheels?

[greif]

Low voltage needs big wire, been a long time since I took the solar classes. Just like you have big cables on your 48 v citicar

[where2]

Originally Posted by greif

Low voltage needs big wire, been a long time since I took the solar classes. Just like you have big cables on your 48 v citicar

My thoughts exactly. So, I put Ben's scenario into a DC voltage drop calculator I found through Google search. I would definitely look for larger wire Ben. Voltage drop calculations yielded the following results:

Voltage drop: 4.04
Voltage drop percentage: 8.42%
Voltage at the end: 43.96volts

I used the following inputs:
Copper Conductors
AWG: 14
Voltage:48
AC/DC: DC
# of conductors: single set
Distance: 100'
Load Current: 8A

I presumed 50 feet out to the load, and 50 feet back to the panel, thus I have 100' of wire for the moving electrons to traverse.

Idealy, something #6AWG or larger would yield results like this:
Voltage drop: 0.63
Voltage drop percentage: 1.31%
Voltage at the end: 47.37

Usually, you want to keep your voltage drop under 2%, because it's just wasting energy. Again, my numbers are all relative to a 100 ft wire run. I don't know what your run distance really will be from the panel, through the conduit to your load and back to the panel.

The reason you can run 15A through #14AWG in a house is because you are running Alternating Current. Direct Current is much worse about voltage drop. That was actually one of the motivating factors in my use of micro-inverters: short DC run, then converted to 240V AC to get from the roof to the service entrance panel.