Solar Swing-Set (PV Playhouse)

This project is a Solar-Powered Swing-Set. No, the solar does not make the swing run. Rather, this project re-uses a child's playset as a ground-mount to support a solar panel.


For some time, I've been playing with solar, and wanted to get more solar power in my life. (See Solar-Powered PowerWheels as an example project.) I already built my own electric car and electric motorcycle and would love to charge those from solar, instead of from the grid.

However, I actually have rather poor solar access at my house. My narrow lot-line runs north and south, as does my home's roof. I have a detached garage, but it's behind a huge evergreen tree most of the day. The only reasonable place for a solar panel is behind the house and next to the garage, but it would have to be at least six feet up in the air to maximize solar access.

While my yard has many trees, it has very few that are any good to hang a swing from. I hung up my bucket-swing on the one branch that I had, but it was far from ideal. A children's playset, complete with a place for swings and a slide would be ideal, but that would also go best EXACTLY WHERE I WOULD WANT TO MOUNT MY SOLAR PANEL.

So, an idea was born. Combine a backyard fort and swingset with renewable energy to create a Solar Swing-Set and Photovoltaic Playhouse!

Lets take a look at tools, materials, and budget, and then dive in to building the SOLAR SWING-SET!

This project is a combination of salvage, carpentry, and electrical work. As such, we'll need the appropriate tools and materials, such as:

Tools:
Impact Wrench
Wrenches
Vice-Grips
Regular and Phillips screwdrivers
Power Screwdriver
Mallet
Marker
Pencil
Digital Still Camera
Volt-Meter
Caulk Gun
Shovel & Steel Rake
Drill & 3/4" wood drill bit
Speed-square
Circular Saw
Step Ladder(s) - 6' and or 8'
6' Spirit Level
Angle-grinder with cut-off disc
Eye protection
Hearing protection
Work gloves

Materials:
A Re-Purposed Playset
48V 405 watt Photovoltaic Solar Panel
6' MC-4 cable
25' 12 awg electrical wire, in red, black, and green.
Plastic outdoor electric junction box
3 x 10' x 3/4" outdoor rated plastic electric conduit
1/2" x 10' metal conduit
3/4" conduit elbows, 2 x 90 degrees, 2 x 45 degrees
3/4" plastic pulling elbow
Metal electrical junction box
1/2" thread-in conduit to box adapters
PVC Primer and PVC Cement
2" and 2.5" deck screws
3/4" and 1/2" conduit hangers
Caulk
Aluminum C-Channel (3 pieces, 48 inches long)
1/4-20 stainless nuts, bolts, washers, lock washers (6 sets)

You will also need an assistant to help take apart the playset, transport it, reassemble it, and to mount the photovoltaic panel to the roof.

While I could have built my own combination playset/solar-panel-mount, a brief look at just the cost of materials told me that I would be better off buying a used playset and modifying it.

To do this, it is neccessary to:

• Locate a Playset (Craigslist, Classified Ads, Rummage Sales, etc.)
• Purchase it
• Disassemble it
• Transport it
• Reassemble it

Locating the Playset
I started regularly viewing through Craigslist for used swing-sets, playsets, and other keywords that might yield good results.

I was specifically looking for a swing-set with a clubhouse with a cloth roof. Typically, the cloth is in very poor condition, but the frame would make good mounting points for a solar panel.

After a few days of looking, I found a playset listed for $200. (I recently did some trading and got a good welding gas tank for free that I sold on Craigslist for $150. This was the foundation of the budget for the playset.) The price seemed acceptable, and I was able to contact the seller and arrange a time to pick it up. I also asked what size hardware the playset used so that I could bring the correct tools.

I got an assistant (my Father), and hitched up a cargo trailer to my pickup truck so that we could get the entire playset in one trip. (It was located about an hour's drive away, and I didn't want to go back.)

Disassembly
We began disassembly, starting from the top, and working our way down. That allowed for easier removal of tall parts (such as the roof) and minimized how much we had to use ladders. The structure is primarily held together with long bolts going into T-nuts, along with a few lag bolts. An impact wrench works great for removing both. On the few T-nuts that were rusted and spinning with the bolt, vice-grips can be used to hold the nut in place while the assistant removes the bolt. We brought along an empty plastic coffee can to hold all of the removed hardware.

Before removing too many bolts, I took digital still photos of each section. This makes it MUCH easier to reassemble. Once apart, many components all look the same. By having some photos of the finished playset, putting it back together is much simpler.

It was starting to get dark and the mosquitos were coming out by the time we had the structure taken apart. Disassembly took longer than expected. If you are doing a similar project, make sure to allow plenty of time and be early enough in the day that bugs and darkness aren't an issue.

Transport
To get the playset back to my house, we strapped all the large components to the utility trailer, and lashed them down with long ratchet-straps. Both roofs, the slide, and long timbers all fit on the trailer. Smaller parts went in the bed of the truck, and were solidly strapped down. It was a Sunday evening, so there was light traffic on the roads. Whenever dealing with transporting large, awkward, unusual items, it's best to avoid rush-hour and busy roads. We rechecked that the tie-downs were still tight after just a few miles of travel, and again at a gas station later.

Reassembly
The next day, I began the process of reassembly. Because this is a solar project, location is important.
I first laid out all the components in my yard to see what I had to work with, and then moved the ground-level components to roughly the final location.

Ideally, a play-set should be built on perfectly level ground. Unfortunately, where it would go does have some slope, so I would have to use blocking under the posts to make sure the entire structure is level. I used a few concrete bricks and scrap pressure treated wood as blocking to level. I placed my 6' level vertically on the main posts to check for plumb.

The structure was reassembled, one piece at a time, from the ground up, in a similar matter to how it was taken apart. There were just a few nuts and bolts that were either missing, rusted, or otherwise unusable. A quick trip to the hardware store made for easy replacement.

Even while looking at the digital still photos, there were still a few components that were a bit puzzling. For example, two of the main upright posts were slightly shorter from the others, something which was NOT obvious while looking at the play-set originally. Looking at screw and bolt holes in various components is a good clue to help figure out what parts go where. 

The most difficult task was raising roof sections into position and bolting them in place.

With the complete structure together, I bolted on the slide, the rock-climbing wall, and hung up one swing. I hung up the bucket-swing next to it, so that the swing-set included both a toddler swing and a "big girl" swing.

Next, I need to mount the solar panel to the roof.

I originally started this project after having a chance to try out a solar panel at a renewable energy fair. I was going to be showing off my electric motorcycle, and I contacted a local photovoltaic manufacturer to see if I could borrow a panel to charge from while at the three-day outdoor event. I got the OK, and was really pleased at how well it all worked!

Photovoltaic panels are typically measured in nominal voltage and in their output wattage. 12, 24, & 48V are common panel voltages. A popular size of panel right now tends to be around 200 watts or so. The panel I chose is a 48V nominal 405 watt panel from Helios Solar Works, which is based in and MANUFACTURES in Milwaukee, Wisconsin, which is only about 30 miles from my house.

I purchased the panel as a "B-Stock", which means it doesn't have a box, and it maybe possibly has a small scratch on the aluminum frame. For all I know, it was the exact same one I borrowed at the energy fair. I called up Heios, ordered the panel, then drove there in my small pickup. I was able to get a brief tour of the plant while I was there. Pretty neat to see renewable energy products being manufactured in my neck of the woods!

The panel cost me $364. Money well spent. You can see the specs of the panel on the manufacturer's web page, at: http://www.heliossolarworks.com/Portals/132436/Sales/9t6.pdf

I brought the panel home and experimented with it a bit. Because I got the panel BEFORE I got the children's playset, I built a very basic A-frame stand for the panel, simply to point it at the sun. Once I was satisfied with the location and that the panel would work right for solar vehicle charging, I moved it out of the way, and then began my hunt for the play-set.

Placement for solar is important. You want to make sure it is somewhere that the sun will shine on it nearly the entire day, and is NOT shaded by trees, other structures, or obstacles. I've been watching this particular spot in my yard for several years, so I know where the shadows fall through the seasons. However, you might want to use one of the many solar siting tools available to make sure you position your panel correctly. (Here's a popular one.)

To mount the panel to the roof, I first needed to attach framing materials to the PV panel, which would in turn be attached to the roof of the playhouse.

On the back of the PV panel are a number of holes, spaced out for use as attachment points. I decided on connecting three pieces of extruded aluminum c-channel to the back of the panel. The spacing was simply one on the center, and the other two on each end.

I used an angle grinder with a cut-off disc in it to cut each of the pieces of c-channel to the width of the PV panel plus about an inch and a half. That allows for enough extra room on the bottom edge of the c-channel to drill a hole and run a lag bolt through it.

I lined up the c-channel on the frame of the PV panel, and marked the existing frame holes. I then drilled 1/4" holes in the channel, and attached them with 1/4"-20 bolts, washers, lock washer and nut.

Because the two roofs of the play-set are off-set from each other, I needed to add an appropriate spacer. The difference in height was 4.25". I took a 2x6 and ripped it to that width, and then cut it to length to match the aluminum c-channel. I then attached it to the end c-channel and the PV panel.

Next, I had an assistant help me lift the panel onto the roof. (Thanks Wayne!) We had to ladders handy and lifted and walked the panel up the ladders. This was actually MORE difficult to get the panel onto the roof of the play-set than it would have been to work on the full-size roof of a garage or house. Because the panel takes up nearly the entire area of the roof, nobody can stand on it to help set the panel in place. Instead, everything had to be done by ladder.

The panel was lined-up so that the center support was directly over the end rafter of the upper roof. With it in position, I ran a lag bolt through the hole in the c-channel, through the roof, and into that rafter. The panel was then leveled (parallel to the bottom edge of the roof) and I ran the lag bolt for the bottom left corner. At that point, the panel was no longer in danger of slipping and sliding off the roof.

On the right-hand side of the panel, I ran deck screws from inside the clubhouse, up into the 2x6 rip attached to the panel.

To support the TOP of the panel, I used the cut-offs from the c-channel, by screwing them down to the far side of the roof. Because they didn't line up with any rafters, I decided to add some to the structure.

First, I ripped 2x4s to 2x3 to match the dimensions of the existing rafters. Next, I measured the length of the existing rafters, and checked the angles on the end. That is a 45 degree cut, or what roofers call a 12/12 roof. After cutting the rafters, I installed them under the attachment points on the back of the roof, and screwed them in place. I then re-ran the screws on the cut-off on the back roof back down into the new rafters.

Behind the panel, I cross-drilled through the cut-offs and into the c-channels on the PV. I then installed 4.5" cross bolts with washers, lock-washers, and nuts.

The panel is now solidly attached to the roof with three points at the bottom and three points at the top.

Wiring needs to be protected from the elements, wild-life, and small children.
The easiest way to do this is to enclose it in conduit.

I chose to use 3/4" PVC electrical conduit. The conduit is affordable, easy to work with, and rated for outdoor use, including prolonged exposure to sun, wind, and rain. It's available from any home improvement store. PVC conduit can be cut with nearly any type of saw, but I found that a plumbing tubing cutter works well, doesn't require any power, and makes a nice clean cut.

Besides the conduit itself, I also needed a square junction box, several right angle and 45 degree elbows, a pulling box to go into the building, and PVC primer and cement.

I mounted the square box to the east peak of the roof. It's convenient enough to get at there (via a ladder), yet is inaccessible to anyone using the playset. I mounted it with stainless steel wood screws, with one of the ports facing down and to the right. The opposite port will allow entry of the solar cable.

I test fit individual sections of conduit, measuring, then cutting, then dry-fitting elbows and other connectors until I had the right number of parts in the correct order to make the run from the box to the garage. I dug a trench from the play-set to the garage, and drilled a 3/4" hole in the side of the garage with a spade bit.

I glued the conduit using PVC primer and cement, simply following the directions on the cans. I put up the conduit onto the structure, with one end going into the box and the peak, and the rest following to the garage. I attached the conduit to the wood with 3/4" conduit hangers and a single deck screw.

With the conduit in place, I could now run the wiring.
The wiring was roughly 30 feet of salvaged 12 gauge solid copper well pump wire. I got this as recycled material from a plumber friend, which mean that it was "free", but I still needed to make sure it was good cable and check it for continuity. Besides the red and black wires, also ran a green wire for the ground (earth) and a heavy string, which could be used to pull anything else in the future through the conduit.

I ran a fish tape backwards through the conduit, lubricated the wires, and them pulled them through. This step is easy to describe, but took a bit of work. The combined wires were actually a fairly tight fit through the conduit. Once the wires were through, I wired up the connections at the junction box at the peak of the roof.

The solar panel has two cables coming off of it; a male and a female MC-4 connection. I purchased a short MC-4 cable for the specific purpose of cutting it in half to make a quick release between the solar panel and junction box. In the box, I ran the cut ends of the MC-4 cable in, stripped the ends and tightened them into two splicing blocks. I then stripped the ends of the red and black wires, slid shrink wrap over them, and  connected them to the splicing blocks, making sure that I had my polarity correct. (Red is Positive, Black is Negative) I then used a heat gut to shrink the wrap onto the connections, electrically insulating them.

I pulled the green wire up to the frame of the PV panel, where it was connected with a screw. With the roof-top wiring done, I filled the top port to the junction box with caulk, and installed the box cover with its gasket and screws.

The MC-4 connection from the panel to the junction box will only be plugged in AFTER I finished everything else in the system. Remember, if it's sunny and the solar panel is plugged in, it's LIVE and creating voltage. Don't plug it in until you are ready. 

Back on the ground, I caulked the pulling box going into the garage and filled the trench back in with dirt.

Inside the detached garage, I would need to run conduit, mount my disconnect box and charge controller, and make my wiring connections.

From the outside of the building, the wiring passes through into the back of a standard metal electrical box. From there, I used 1/2" metal conduit, to match what was already inside the garage. (I also happened to have plenty of 1/2" components on hand, saving me cost and a trip to the hardware store.)

Next, I mounted the disconnect box and charge controller to each other with a stock electrical connector designed for just such a task, and screwed both down onto a piece of wood. Then, the entire piece was raised against the wall, positioned for the conduit to easily reach it, and attached with four large wood screws.

I ran the conduit into the bottom of the disconnect box. The disconnect serves two purposes. It is a master ON/OFF switch for the solar panel AND it contains a fuse to add over-current protection to the system. The black wire is tightened down under a screw that simply passes through power, but the red wire gets tightened under a screw that only connects the power to the fuse when the switch is on.

Next, I cut two short pieces of 12 gauge wire to run from the disconnect to the charge controller. Again, it's a simple matter of stripping a wire and tightening the ends of it down under a -set-screw. The connections of the charge controller are well marked, and the installation manual makes it clear which terminals to use.

After that, I attached an Anderson connector to the bottom of the charge controller. The two wires from the connector go to the terminals marked for the battery in the charge controller. I ran two skinny wood screws through the Anderson connector to mechanically mount it to the wood.

I already had a special cable made up with an Anderson connector on both ends. This is my battery cable that will reach either the 48V electric motorcycle, or my retro 1970's electric car. Both are wired up with a matching Anderson connector to the battery pack. This allows me to connect either vehicle to the charging system.

I simply plug in one end of the cable to the charge controller, and the other to the vehicle.

It's also nice to be able to see the voltage of the battery pack and the amperage of the charging from the solar panel. Because there is a meter available for sale for the Xantex C-40 charge controller, I simply purchased one. I replaces the existing face-plate on the controller and is as easy to install as plugging in a phone cord. With it in place, I can see voltage, amperage, and a running total of amp-hours.

With the solar panel in place mounted on the roof, the wiring and conduit complete, and the disconnect and solar charge controller all in place, we just have to turn it all on.

I plugged in the cable between the charge controller and electric motorcycle. Up on the roof, I connected the solar panel to the pigtail going to the junction box. Then, in the garage, I simply flip the disconnect from OFF to ON.

The C-40 controller displays the battery pack voltage and the current flowing from the panel to recharge the battery. In bright sunlight, and a mostly discharged battery, the current should be relatively high. (The most the panel can put out is 8 amps at 48V.) As the batteries charge, the voltage will rise and the current will drop.

The motorcycle has a 55AH/48V battery pack. In theory, if it was 100% discharged (which you never want to do to a battery!) it would take 6.875 hours to recharge at 8 amps, the maximum output of the solar panel. In reality, the battery pack is never run more than half-way down, but it also typically charges slower than 8 amps. Available sunlight also varies depending on weather and time of year. (Although there is MUCH more sunlight in the summer, which is when I use the motorcycle the most.)

In a nut-shell, I can get up to 30 miles of range on my motorcycle in a day's sunlight. Should it be bad weather, I can always use a traditional charger, plugged into grid power.

Cost Breakdown of Materials and Components:

• Used Craigslist play structure - $200. I had a large welding gas tank that I got for free just before doing this project. I sold that tank on Craigslist for $150. That gave me a rough budget. When I found the structure I wanted to buy, it was only $50 out of pocket.
• Helios 9T6 series solar panel (as B-stock) $364
• MC-4 Cable - $13
• Disconnect Box - sunk cost, already owned, originally bought on clearance at hardware store
• C-40 Solar Charge Controller - sunk cost, already owned, but originally a little over $100
• C-40 Ammeter/Voltmeter Display Faceplate - $85 (That was my "splurge" for the project!)
• Wiring - 12 awg Red, Black, and Green wires, about 30 feet - "free", salvaged material
• Conduit, hangers, junction box, pulling box, deck screws,assorted electrical connectors, bolts, and lag bolts - about $50 and several trips to the store.
• 2x4s for rafters, aluminum c-channel for the panel mount, and some other assorted materials were all scrap or salvaged items which were already paid for by "sweat equity". If you are doing a similar project from scratch, you will have to account for costs of these materials.

Total out-of-pocket costs for this project were $562. For that cost, I got:

• A cool club house for my little girl to play (permanent upgrade to the cardboard clubhouse)
• 2 swings (and a real place to hang the bucket-swing)
• A slide
• A trapeze bar
• Monkey bars
• I neat place for me to read
• Rock Climbing Wall
• Tree Frog Habitat
• Transportation Energy Independence
• 405 watts of renewable energy
• A way to recharge my "Poor-Man's Smart Grid"
• Satisfaction that I'm doing something right

So how about you? Are you interested in solar energy and would love a great starter project? If you are concerned that solar is too expensive or complicated, don't worry, it doesn't have to be. There are great resources and publications like HOME POWER and the MREA!

Pick up a book, access the internet, take a night-school class, and when you are ready, build your own Solar Swing-Set, Photovoltaic Play-Set, or Renewable Energy Club-House!

Besides simply reassembling the play-set and installing the solar panel, I also found that the original design of the structure was missing something - good cross-bracing!

There were a couple of short pieces of cross-bracing in the one dimension, but NONE in the other. Even after the entire project was together, it was still a little shaky. So, I decided to add some additional cross bracing.

To do so, I would measure and cut some 3/4" metal conduit, flatten the ends, drill holes, paint it, and then mount the conduit to the structure.

To start with, I measured from near the base to close to the ladder, noted the measurement, and cut conduit to that length. Again, a regular tubing cutter worked well make a clean cut on the pipe.

I then flattened both ends of the tubing. I first measured how much of  each end would need to be flat (where it would be directly against the structure.) I then hammered the tube on my anvil with a 3 lb. sledge. (To see the Instructable on how I made the Anvil Stand, click the link.)

Next, I drilled holes through both of the flattened ends. I drilled over the hardy-hole in the anvil, so the drill-bit could just pass through after it was all the way through the conduit.

I then hung up the two conduit pieces and painted them with green Rustoleum brand hammer-finish paint. It's what I had on-hand and matched the original conduit fairly close.

Finally, I mounted the cross-bracing to the structure using a lag bolt at the bottom onto the 4x4 post, and a carriage bolt into the thinner wood at the top.

With the cross-bracing in place, the structure felt much more solid, and is now ready for children to jump, swing, and slide on it!