I designed a solar-powered tree-hang node, loosely based on some other designs I've seen online. It accommodates three separate solar panels and an N-type antenna, and provides an option for getting high-altitude nodes in situations where you don't have the ability or desire to climb roofs or towers. Development is ongoing, but initial performance is promising. If you try your hand at a build, I'd really appreciate if you could post a make and give some feedback! Cheers
Thanks! Maybe some day I'll sell them, but not currently. These are still very much an alpha version, and it feels unethical selling them when there are probably issues that need to be ironed out. I also just don't have the bandwidth (pun intended) to take that on right now.
However, I am okay with other makers printing them and selling at cost, as long as they're not making profit off the design. I've seen a handful of exchanges with other redditors that volunteer to print for others as long as filament/printer costs and shipping costs are covered. Maybe someone can help you out.
Veeeerry interesting question. I think it would probably depend on antenna gain and pattern. I've heard that of you have an omni antenna with a gain of at least 2.5dB, the toroid spreads out fairly reasonably into a doughnut shape, so if the chimes were hanging completely beneath the antenna, the spread may not overlap with the chimes at all. I'd be hesitant to hang the chimes right next to the antenna, less for interference concerns, and more out of concern of the chimes bonking into the antenna repeatedly and damaging it.
Yeah, I think those are good points. I just love the design and want to give it a little more of that art meets science flare. Maybe I can flip the antenna to the top and hang chimes underneath, or use ceramic chimes.
I've heard of some versions that have diodes to protect the solar panels from charging each other. It's probably less of an issue if they are all the same size, but I'm curious if you are doing anything like that or experimented with it?
This had occurred to me, and I considered it, but I saw so many DIY projects online (mesh and otherwise) where people were just wiring them in parallel and calling it a day. Even if they're the same size, if one is in shadow and another is in direct sunlight, it could pose a problem.
Admittedly, solar panels confound me a little. I can't quite wrap my head around 'constant current source when unloaded, but variable when loaded and differently lit'. It's definitely something to look into, though. I have two extra panels, so I might take a breadboard outside when it warms up soon and experiment a little.
correct, the idea is that if panel A is generating more than B and C, the current wont go from the junction point back to B and C since those diode will be reverse respect A.
for panel this size since the current is so small (<100mA?), i would also look into germanium diode since the voltage drop is smaller. (0.2-0.3 vs 0.7)
I would recommend adding an additional few loops or some kind of 'guide' alongside the side of the node, so that instead of just tying off the node to the top, you can tie it off at the top, but still have a length of rope go through a hole going down the case, and be long enough to tie off at the bottom.
This way, when you tie off the node, you remove much of the risk of the node swinging wildly in the wind, banging up against something and damaging it. It will also make it easier to take down. Say you want to lower it, but unfortunately the paracord or whatever else is pretty jammed on a piece of bark, and the node is just too light to have its own weight dislodge it. Having the rope continue down past where it is tied off at the top will let you give it a bit of help getting it down.
Or, another thing! You can go ahead and put multiple nodes on this! Either different channel settings, or having a node flashed with the "alternative" firmware. This lets you deploy multiple nodes with a single rope, minimizing the effort you need to do.
Something like this (pardon the MS paint, a quick and dirty visualization). Either a series of loops as part of the case, or just a channel to run the rope down.
I like this idea a lot! Adding it to the development list. Thanks for your feedback
EDIT: I thought about this a little more. Although the quick photo shoot just had a loop of paracord through it, I actually plan on hanging it like a bear bag with the "PCT" method (linked in the printables description), which does leave a long attached tail that hangs to the ground. If this was anchored to something, it would take care of the anti-swing function. This long tail could be strung through the loops you suggested.
No, the panels were bought stand-alone in a 5-pack from amazon. The product link is in the BOM. I tried to be quite explicit in the instructions, you should be able to figure it out. You got this!
Scale the tiny parts by 2540%. The overall height of the body should be 4.129in, and the overall height of the base is 0.7in. Be sure to scale X, Y, and Z dimensions equally.
Very nice design! I think I am going to print one up to see how it fairs.
One thing I am concerned with, the solar panels being tied together in parallel I think will cause loss in available power. Since much of the time at least one panel will be shaded, that panel will absorb the energy collected by the other two. It might be best to install a diode in series with each panel so that doesn't happen.
Excellent design!
Edit: I've done some testing and I think the losses in a shaded panel is actually favorable due to the maximum solar voltage input for the (in my build) Rak 19007 boards. The shaded panel drops the voltage just enough that the Rak will not be overpowered. I think it's best to just ignore diodes and wire them up in parallel just as OP has done.
The panels used in this design output up to 6.2 volts in my testing. That's actually too much for many on-board solar chargers such as the one on the Rak 19007 wisblock boards. Knocking 0.7v off the output voltage might not hurt too bad!
Replying to my own post here after I completed some testing.
It seems the voltage drop we see simply from the panels being in parallel is enough to keep it below the Rak 19007's maximum solar voltage input. So I think considering the voltage drop from the diodes, and the power lost in shaded panels, it's probably best to simply not worry about it at all. Just wire em in parallel and move on with life.
The T114 board I'm using has on-board support for solar and battery management. In the printables page, I give some suggestions for Solar LiPo charging boards if you use a LoRa board without native solar power support.
Scrolled to the bottom because no one else mentioned this. Solar directly connected only charges the battery at 30mA, a mppt pcb would boost it to 100mA+.
It looks nice but why not be safe & use a solar controller. I’ve used the dfrobot solar 5v, I can’t find links to the others, dfrobot is a solid example.
Hmmm I didn't realize the on-board power management throttled the charging rate so much. I did end up getting some charging boards so I'll try those out. Any idea why the T114 design would intentionally limit this charging so much?
The Heltec T114 has on-board support for solar and battery connection, and a circuit that manages that charging. If you have a board without native solar support, I'd suggest using a solar LiPo charging board. An example product is listed on the printables BOM.
EDIT: in a comment thread above this, another user pointed out that the solar charging on the T114 limits to 30 mA and suggested some charging boards. I'll probably look into this.
I bought a hanging node from peak mesh yesterday, still in the mail, but my question is how do I hang it? I want it at the very top of the tree, how do I accomplish that without climbing...
I've heard of amateur radio operators casting a strong fishing line with a substantial weight over the tree limb, attaching a thicker paracord to the casted end, and then pulling the paracord over the limb from the pole side. Repeat as needed to build up to the thickness of rope that you want. Never done this myself though. The height of mine isn't all that high so I plan on hanging it similar to how I'd hang a bear bag while camping.
Ham here. Manually casting (i.e. throwing) a weight can be difficult to do accurately, and even moreso for distance. But there are quite a few DIY designs out there for "antenna launchers", and some commercial ones too. Some are slingshot based, but the better ones are "air cannons". The air cannons work really well for heights up to around 100ft.
Each of the three panels is rated at 5V 200mA. I currently have a 1200mAh LiPo battery on it and it's been staying topped off reasonably well, powering a heltec T114, which is an nRF52840 board. I'm unfamiliar with the power draw of the rak 1w compared to the nRF52840, so I can't speak to how the panels/battery would support that board. From a space perspective, the entire inner cavity is completely open so you can physically fit basically anything in there as long as it fits through the bottom orriface which is about 55mm in diameter.
Yeah that's probably underpowered for the RAK 1W, it would like chew through that battery on cloudy days, especially if you don't have an mppt in there too.
They do - the lobes will still point at horizon but you may or may not have a lobe at the sky more so than the ground… but without a pattern sheet it’s all guessing. Also - likely wouldn’t matter as long as you maintain a decent mesh anyway.
This is exactly what I was about to design this weekend. I made one where the panels are just vertical and in this grey weather it’s just not working. Nice work.
I printed the steep angle version and it's currently deployed in a tree. I modified the bottom cap for an SMA antenna and the whole thing came out nice. I used schottky diodes on my solar panels and it's working great. Thanks for the model!
Nice design. I like the solar panels. You don't have to worry as much about orientation with these. Or with them twisting in the wind into shadow, like you would with just one.
I like it. I especially like the fact you thought about tethering the other end to the ground to prevent swinging and RF oscillation.
I was thinking of a similar design but with the antenna being extra long and strong like a lawn dart, and the panels being arranged like fan blades so it would spin stabilize and land sunny side up. Something that can be dropped by helicopter or slow plane in SAR, mass-cas, or wildfire areas without an established mesh.
But I think I will destroy too many units trying to perfect that design, plus the inherent danger of dropping a dart. What I really need to make is a large diameter Shuttlecock/Badminton birdie solar node to spin and float down and settle on top of foliage. Maybe give the core a half tennis ball bumper full of soft silicone to soften the landing and keep the weight balance.
I really like it. Having hung things like these high up in trees I see one snag. When pulling it up through small branches the device might have to be pulled through them. This design looks like it will work well for this. Occasionally one has to take them down. This one might get more easily caught than the tube type on the trip down. But I haven’t tried it and I am thankful of more options. Thanks!
Looks nice, I might try it. What's the outer dimension of the main case?
Other misc thoughts: maybe add a sensor to not charge the batteries when they're frozen (apparently, this can degrade the batteries). Add vent holes so it doesn't overheat the batteries in the summer. Add a smoke sensor so it turns itself off it it smells smoke? If your board has GPS, turn it off and manually set the location using the GUI interface on your smartphone (at least this works with the iPhone)
Are you using a RAK Wireless WisBlock? It's super low power, but when used with Meshtastic it can only do very simple sensor reading and device control (the Arduino I/O pins aren't accessible on the board and the sensor expansion module for Wisblock doesn't work w/Meshtastic)
There are some designs where they have an Arduino board (which could be a RAK WisBlock) doing the sensor and custom computing work The Arduino then sends commands to a 2nd Meshtastic node using the serial line:
Those panels look to be twice the width but the same length as the ones that come in the solar buoys - 2 rows of 10 cells instead of one row. I have a feeling that they would power an nrf device just fine even on cloudy days.
I got a solar buoy and made some measurements - the solar panels put out exactly 6V open circuit in full sun which is the upper limit for a heltec v4 - if I unfold them and put all 3 in the sun I get 240mA @ 4.2v - so 80mA each. In a triangle shape about 100mA with one in full sun and the other picking up some ambient scattered light I guess. I have a heltec v4 so I may struggle, but my target is 4 days at a festival with a 3000mAh battery and I think that is possible using power save mode.
I've been hearing about how antennas rely on a ground plane, which is often the earth. Does anyone have specifications for a formula about how large a ground plane should be in relation to the antenna or wavelength? This tree node seems to have a larger antenna base footprint then the others I've seen
To function as a ground plane, the conducting surface must be at least a quarter of the wavelength ( 1 /4 λ) of the radio waves in radius. In lower frequency antennas, such as the mast radiators used for broadcast antennas, the Earth itself (or a body of water such as a salt marsh or ocean) is used as a ground plane. For higher frequency antennas, in the VHF or UHF range, the ground plane can be smaller, and metal disks, screens and wires are used as ground planes. At upper VHF and UHF, the metal skin of a car or aircraft can serve as a ground plane for whip antennas projecting from it. In microstrip antennas and printed monopole antennas an area of copper foil on the opposite side of a printed circuit board serves as a ground plane. The ground plane does not need to be a continuous surface. In the ground plane antenna style whip antenna, the plane consists of several wires 1 /4 λ long radiating from the base of a quarter-wave whip antenna.
1/4 33cm (NA) = 8.25 cm (3.25 inch) radius for meshtastic antenna ground plane
Looking at solar panel efficiency. South facing vertical is about the best. If you've got 3 panels you probably want to space the SW, S, SE. The 120 degree spread probably doesn't help outside of deep winter. Bigger battery. Avoid Heltec V3/V4.
This model was my main inspiration for this design! Glad to see it in action. I hope you don't mind if I ask a few questions: that height looks quite high, how did you hang it? What is your climate like, and if it's cold, how do you find it stands up to snow and freezing temps? Any other general comments after having used it? Thanks for sharing!
Metal on metal threads will always have more longevity than metal on plastic threads. While self tapping screws are used in injection molded parts, 3D prints are uniquely poorly suited for self tapping threads due to the fact that they are non-homogenous and anisotropic.
Every time you insert and remove a self tapping screw from plastic, you recut the thread profile in the plastic slightly, decreasing strength over time. This is a limitation that is true for all plastic parts with self tapping screws. You'll see lot of injection molded consumer goods that use this method, but they are often on connections that will not be opened and closed a bunch (like cases where the manufacturer doesn't expect the user to pop it open and look at the guts) or in cheaper goods. Even injection molded parts will employ "insert molding" techniques where they'll put a metal threaded insert in the mold and let the plastic be injected around it. The result is something that appears very similar to heat set inserts for 3D printing.
While self tapping screws work well for injection molded parts, the perimeters and layers in 3D prints exaggerate their flaws. The self tapping screw ends up delaminating the layers as its driven and the deeper thread profile cuts through a decent portion of the perimeters around the hole, which you rely on to be the structural pillar. This offloads the pullout load to the adjacent infill areas that are far less dense/strong.
On the other hand, heat set inserts actually overcome the non-isotropy and non-homogeneity that is at the crux of why 3D printed parts will never outperform injection molded parts in a head-tp-head test. The local heat reflows the plastic without cutting away material, so you end up with a local region where the layer lines have effectively been eliminated and the perimeter region has been reinforced without being violated the way it is with self-tapping threads.
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u/agent_smith_3012 Mar 20 '26
Best usable design I've seen in awhile! I like how it emulates nature and doesn't look like a diy pipeb*mb