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Solar rnode up a pole

This project is a solar rnode setup providing a rnode radio that runs 24/7 on only solar power. The lora rnode radio is at the top of a pole and connected by a 10 m USB C cable to a Raspberry Pi 4 at the base of the pole. The USB C cable runs up the inside of the pole. The USB C cable provides power to the rnode and data transfer between the Raspberry Pi and rnode. The rnode sits on the top of the 10 m high pole (mast) so it sticks out above the roof. In this case I am using a spiderbeam as the pole. Using the a tall spiderbeam pole (mast) provides much improved reception and transmission to other rnodes in the town where I live, as compared with using the same rnode under the roof in the attic. The spiderbeam pole is attached to the corner of the railings of a balcony. Being on the balcony provides yet more height that the pole alone. An alternative way to deploy a the spiderbeam pole is to attach the spiderbeam to the trunk of a tree with bungee chords or similar, in which case the rnode sits in the middle of the tree canopy, or better still sticks out of the top.

This project is not a low cost setup. If cost is a major issue, then the build here might not be to your liking. The battery in this project was the main cost, but I already had the battery anyway. The design at least works: both in terms of providing 24/7 solar power off-grid operation, and in terms of the radio reception provided.

The Raspberry Pi is powered by a balcony solar power station. The solar power station has a large 24 V LiFePo4 battery which has two USB A output ports built in, one of which then powers the Raspberry Pi. The aim of this project was to demonstrate/test that even rnodes that require, as in the case of the Raspberry Pi 4, as much as 2 W of power, can be set up to run 24/7 if one scales the components correctly. A Raspberry Pi 4 with an ESP32 node will use about 4 W, but with a RAK/T114 only about 2 W.

The project uses an unnecessarily large 100 Ah 24 V LiFePo4 battery which I had bought for another project that never came to fruition. (The project was testing storing night-time electricity when it was cheap and feeding continuously, into the house mains electricity system, about 100 W of that stored energy that during the day, which does not work profitably, over a liftime, due to the dire conversion efficiencies of DC to AC.)

What about freezing temperatures? It is not ideal to charge a LiFePo4 when it is freezing. This is a big topic. The whole issue can be avoided by using a lead-acid battery. I simply carried on with the LiFePo4 because the amount of charging current when cold is normally so small, and the really cold periods were at night when there was no charging anyway. Importantly, the solar power station's box can get very warm very quickly when the sun shines on it, thereby raising the battery temperature when charging takes place. This can be monitored over long time-scales using a Govee WLAN temperature and humidity sensor which has an excellent app that can provide alterts. There are LiFePo4 batteries available that keep themselves at the right temperature, and such a design would be preferable for longevity. There are also thermal switches by KEMET, part TRS1-0MSR01EV available that would be able to disconnect the solar panels when the ambient temperature is below 0°C, but I have not implemented this solution yet.

The solar power station sits on my balcony, and uses a 100 W solar panel attached to the railings of the balcony. The solar panel is vertical and faces east. Such arrangements are normally called balcony power stations, or Balkonkraftwerke, and are increasingly popular due to the ease of setup. Using such a balcony solar power station also for a radio project makes perfect sense if one considers that one should anyway have a solar power station for a home in case of grid problems. The radio project just piggybacks on the balcony solar power station. The idea in this project is not to maximise the solar power harvest. The idea is that a large enough panel will keep the radio running even from indirect sunlight, and the periods of direct sunlight in the early morning for this east-facing setup, is plenty to keep the battery topped up in face of the small power draw of the Raspberry Pi rnode.

The project is presented with this large battery attached, and with a 100 W panel. However a much smaller battery could be used, scaled down to provide sufficient energy reserve for the rnode to work even when there is very little sun indeed for typical worst-case dark periods typical for your region in winter. In this case, however, I want the second USB A power output of the battery to be available to power sensor arrangements for reporting telemetry data to the Pi, to be then reported in real-time to a site in the Reticulum NomadNet mesh. An example of telemetry is a weather station.

This video is a good overview of the energy requirements of various Raspberry Pi boards, and is very informative to help chose a battery for your Pi. The video demonstrates that even a simple motorcycle lead-acid battery can be sufficient. The best (and safest) battery choice for low temperature use can be a lead acid gel motorcycle battery, which is also good value.

The Pi for running the rnode

This build uses a Raspberry Pi 4 set up according to these instructions. The Pi is in a fanless case, but if you want wifi access to the Pi, then such a fully metal case might not be optimal. Update: I think putting a Raspberry Pi Zero 2W into the box up the pole is probably better in view of data cable problems that developed.

Off-the-shelf solar systems pitfalls

I struggled for a very long time indeed to use a simpler, off-the-shelf, plug-and-play solar and battery system from Jackery: Explorer 100 Plus with SolarSaga 40 Mini solar panel. But that was a complete disaster that did not even come close to workigng for 24/7 power provision. The battery was, staggeringly and unbelievably and laughably, drained by the pannel at night. Jackery had no answer to this utterly shameless obsurdity. Not even electrically cutting off the pannel at night automatically with a light sensor was able to make the system work as I wanted 24/7. The display of remaining capacity on the Jackery Explorer 100 Plus battery was also fantasy, and the battery switched off, due to being empty, long before the display indicated it would. To this Jackery also had no answer. Those products were unfortunately a complete and utter waste of time for my 24/7 use case. Once bitten, twice shy, I gave up forking out for any other "off the shelf" solar setups and went for this brute-force solution presented here. On a positive note, the Jackery Explorer 100 Plus battery is the only battery I found that was good for running low power nodes for a long time because it allows you to switch off the function by which the battery cuts output when the power used at the output is low. This automatic cut-off at low power use makes nearly all off-the-shelf batteries completely useless for low power radio proects. (The Jackery system is also ideal for when travelling/camping.) The power control circuits of the black box off-the-shelf batteries are nightmare for incorporating into any self-built systems. Making your own battery setup using OEM (Original Equipment Manufacturer) components is almost the only efficient way of progressing a project. If you ever find an off-the-shelf system that works to run an rnode 24/7, do please let me know.

Putting the rnode onto the spiderbeam

Parts list:

1. Housing/box for the rnode: 100 x 60 x 25 mm project box. This box is not really waterproof around the lid, but with a lot of tape it works fine. If you are using a Raspberry Pi Zero 2W in the box you will need a larger box.
2. Radio rnode: use as small a node as possible because it has to sit on top of the spiderbeam mast in the small box, for example the Lilygo T3S3, or RAK, or T114. I have better radio results with the RAK than the Lilygo. Flash the firmware onto the node.
3. Optional step: I used a RAK4613 node and a supervisory circuit (MCP120-315GI/TO) selected to issue a reset signal if the voltage seen by the RAK node is wrong. I did this because the node stopped working once, and I wanted to see if this approach (suggested by a colleague) would help prevent me having to lower the pole and press reset on the RAK node. This approach is a bit speculative but I thought it could do no harm and might help keep the rnode running as long as possible. The soldering is a bit fiddly. I also used a 0.1 micro-Farad ceramic capacitor (Kemet C320C104K3R5TA, Digikey part number 399-C320C104K3R5TA-ND) as shown in the datasheet figure 2.1

4. Antenna for the rnode: Taoglas FW.86.B.SMA.M - Antenne, ISM, 850 ... 890 MHz, 240mm, 3.5 dBi, SMA male, Distrelect Art. Nr. 302-85-131 Manuf. Part. FW.86.B.SMA.M
5. Antenna connector: to connect antenna to the rnode, and provide a mounting of the antenna to the housing/box, IPEX to SMA adaptors which includes a thin threaded nut needed to fix the adaptor to the box.
6. Tall pole: Spiderbeam GFK mast, 10 m (SKU: 18362.10). This mast/pole consists of many concentric, slightly conical parts which friction-fit together when expanded. When collapsed down it is not long. It is easy to manipulate alone when extended. It is not heavy. When collapsed down the tubes are very slippery and will slide out very fast if tipped, so one needs to have one hand at each end when manipulating/carrying to stop the parts from sliding out when you don’t want them to.
7. Fixation means to fix the box/housing to the spiderbeam pole's distal terminal end: M22 cable gland is used to fix the housing/box onto the top of the spiderbeam. Rubber o-rings help fix the cable gland to the pole to stop the housing wobbling. Using o-rings pushed into the cable gland around the spiderbeam pole top was the key step for good attachment of the housing to the top of the spiderbeam. So you will need a good o-ring set which will typically have suitable rings in the set. If you have no o-rings it might be best not to implement this project, unless you can think of an alternative.
8. Small waterproof box for the Pi: the box should allow the USB C power supply and USB cable from the node to enter the box, but keep the box contents dry. I use a box with rounded edges and an overhanging lid, and the cables enter between the lid and box side from below.
9. Cable to the rnode from the Pi: this has to be sufficiently long, about 10 m. I was not able to find a single cable as long as the 9 m or 10 m required and that was able to provide data transfer. So I used several USB C cables daisy-chained together. Make a suitably long USB C cable by using multiple 3 m lengths of USB C male-male cables daisy-chained using USB C female-female adaptors. I used a heat gun and adhesive heat-sensitive shrink-wrap to make each joint very fixed and essentially waterproof. If you do not heat-shrink the joins then the cable joins at the adaptors will come apart or loose during mounting of the spiderbeam pole. This is because there is tension put on the cable during extension of the spiderbeam. Using adhesive shrink-wrap is probably not essential, one could use normal heat-shrink tubing. The adhesive variety makes a sufficient sticky mess of the join that the parts will probably not want to be used again. Normal non-adhesive heat-shrink is probably adequate to provide the mechanical strength needed at the joins.
10. USB C to USB A adaptor: to connect the Pi to the node's long USB C cable, such as the one in this set.
11. Slotted support: the USB C cable protruding out of the base of the spiderbeam needs to be protected from the cutting/compressoin effect of the spiderbeam tube, or edges, when it exits from the bottom section of the spiderbeam. This can be achieved by exiting the via slot in a slotted base upon which the spiderbeam rests. I used as a base a piece of rubber with a slot .

Tools and supplies needed:

• String to pull the USB C cable out of the spiderbeam end section.
• Step drill (Stufenbohrer) for making the large diameter hole for the cable gland.
• Electric drill, or electric screwdriver, and 6.5 mm drill bit to make the hole for the antenna adaptor.
• Heat gun.
• Waterproof sealant: Sika - Sikaflex-291i, Strong Adhesive Marine Sealant- really sticky stuff!
• Waterproof tape: 3M 80611207012 33+ Scotch Super Electrical Tape, Vinyl, 19 mm x 20 m, Black.
• Fixation means for fixing the spiderbeam pole (mast) vertically: I used several, strong, thick cable-ties to fix the spiderbeam mast into the corner of the railings of my balcony, with wooden blocks as spacers to make it vertical when fixed.

Build steps for the spiderbeam mounted rnode:

1. Make a USB cable of suitable length using the parts above, by daisy-chaining the USB C male-male cables using the usb c female-female adaptors and heat-shrinking the joins. I made the cable as short as possible, in case excess length were to become a problem for the data transfer reliability. Update: this cable seemed to have caused problems. It might be better to place a Raspberry Pi Zero 2W into the box and use only a single USB power cable up to the Pi and radio in the box.

2. Remove the thinnest two rods/tubes from the spiderbeam mast set. The last two were too small in diameter to pass the USB C cable connector. This reduces the length of the pole by about 1 m. Take the remaining, now thinnest, tube of the spiderbeam. With the help of a piece of string, pull the USB C cable's USB C jack, of one end of the cable, out through the thinnest mast portion so that it sticks out. With the cable sticking out, feed that thinnest part of the spiderbeam back into the remaining collapsed spiderbeam mast portions.

3. The spiderbeam has a screw-on cap at one end. Drill a hole in the screw-on cap of the spiderbeam to allow you to feed the other end of the USB cable through the spiderbeam cap. To do this I used a mixture of step drill, 10 cm drill bit, filing and swearing. There is a foam insert in the screw-on cap, and I made a hole in that and pushed the other end of the USB C cable through that and out through the screw-on cap. Feed the 9 m of cable through the cap, and then screw the cap back on with the USB cable sticking out of it. Then you have a collapsed spider beam with part of the USB cable running through it and a long, approimately 8 m USB C cable, at the cap end. The cap is not essential in my view, but stops all sorts of accidents like the tubes sliding out when you do not want them to, which happens in the blink of an eye when you least expect it becuase the spiderbeam sections are very, very slippery.

4. With the step drill, carefully drill a large hole centrally in the box/housing's base, in order to fit the fat cable gland into that hole. Make the hole only just large enough, so do it carfully, step-by-step, checking each time if the gland already fits for the hole you have drilled at each step. When the hole is the right size, insert the cable gland, and fix the cable gland firmly to the box with the thin plastic nut of the cable gland. Remove and discard the rubber o-ring element that comes with the cable gland. Place the cable gland's external dome-shaped part over the distal end of the Spiderbeam mast section. Feed the distal section a little though the part of the gland in the box/housing, without leaving any protruding beyond the gland itself. Tighten the dome-shaped cable gland part tightly to fix it, and thus the box, to the distal part of the spider beam mast section. Using a flat-head screwdriver, or similiar, stuff o-rings tightly into the gap between the spiderbeam and the gland to fix the housing tightly so that the box is not able to wobble.

5. Mount the LoRa antenna centrally to the lid of the housing as follows. Drill a 6.5 mm hole into lid of the housing, to take the SMA connectors of the IPEX to SMA adaptors. Fix the adaptor onto the lid using the thin nut that comes with the adaptor. Put a bit of waterproof sealant around the adaptor so that there is no point of entry for water. Attach the antenna well to the adaptor.


The image shows a Lilygo T3S3. The second lower thin cable is related to a bluetooth connection which is not used in this build.

6. To provide some essential strain relief, I tied a knot into the USB C cable, at the end in the housing. This knot being larger than the diameter of the spiderbeam at that point, it prevents any tension in the cable reaching the rnode USB C port when it is in the housing and the USB cable is attached. If there were no strain relief, mounting the spiderbeam would, via the cable, put too much force onto the node at the USB socket.

7. Attach the IPEX end, of the IPEX to SMA adaptor, to the rnode. Never power the node without an antenna attached, as this can damage the radio circuitry due to overheating. So do this step before the next, and persuade yourself that the connection is good.
8. Attach the distal end of the USB cable to the node in the housing.
9. Test to see if your rnode works when the proximal end of the USB C cable is attached to the Pi (via the USBC-to-USBA connector) and the Pi powered up (from an external power supply or other temporary battery).
10. Close the rnode box/housing by putting the lid on it. Then you have something like what is shown below (the image shows an extra bluetooth antenna, pointing downwards, which is not used in this build).

Balcony solar power station

Safety first: do not go anywhere near the battery, nor hold any tools when working near the battery, without wearing these protective electrically insulated gloves. This is due to the danger of a tool or hand shorting across the terminals of the battery. Also, use only properly insulated tools to work on the battery itself, similar to this adjustable spanner. I would wear goggles when working with the battery because if you accidentally short the terminals with something, the thing used to accidentally short the terminals gets chunks vaporized out of it in an flashing, explosive cloud of molten metal - not nice to have in the eyes. How do I know this? .... see below.

Parts:

1. Solar power station housing: a large-enough waterproof and weatherproof box, out of which you can run a few cables. Ideal is a plastic box with lid. I enclosed the whole box also in a plastic bag to give another layer of waterproofing because the box was not water/rain tight of itself. If the box is made from a softer type of plastic, then you can, with a knife, make the necessary entry/exit points for the solar panel cables and USB power cable to the Raspberry Pi (which in this build in in a separate second box next to the box for solar power station). Obviously make the calbe entry points at places that water is not most likely to enter. I put the Pi into another smaller waterproof box next to the solar power station, so that I do not need to open up the plastic bag cover just to access the Pi, should the need arise, to attach a screen, keyboard and mouse.

2. The battery: 24V 100Ah LiFePo battery with built-in USB outputs with sufficient current output for the Raspberry Pi. The battery has two USB outputs, each rated at 5 V & 2.1 A.

   If your battery does not have USB outputs, it is a simple matter to arrange a USB output using a DC-DC 24V/12V to 5V 5A Buck Converter, or DC-DC Step Down Converter 9-36V to 5V 5A Buck Converter, or the very nicely packaged and USB-C wired Bauer Electronics DC-DC 8V-32V to 5V Voltage Converter USB-C 3A 15W Buck Converter. I have, however, not tested any of those devices. You will then, of course, need suitable cabling and/or battery connectors.

3. The solar panel: the solar panel has to be higher voltage than the battery, and so I used a 36 V 100 W panel because I already had the 24 V LiFePo4 battery. This size (100 W) provides enough power even from ambient light. I only considered using panels with eyelets, which tend to be flexible and lightweight ones.
4. Cable ties: to fix the solar panel to the railings of the balcony.
5. Solar power charging manager: Victron Energy SmartSolar MPPT 75V 15 Amp 12/24 Volt Solar Charge Controller (Bluetooth), which has a great app to monitor your charging (via bluetooth). The device takes care of charging the LiFePo4 battery.
6. Cable: cable from battery to solar power charging manager.
7. Battery status: It is very useful to know what state the battery is in, especially in case you need to spot any problems.

   (1) (useful) Victron Energy Smart Battery Sense (Long Range up to 10 m) – Battery Voltage and Temperature Sensor which has great app (via bluetooth).

   (2) (optional) To measure the state of charge of the battery Victron Energy SmartShunt IP65 500 Amp Battery Monitor (Bluetooth) which also has a great app (via bluetooth).

8. Cables: for the SmartShunt battery state of charge measurement device
9. Switch: to switch off current from battery, which is useful to avoid issues when connecting or disconnecting things and avoids sparking.
10. Cable tidy: to control the spaghetti use a cable conduit in the solar power station box.
11. A USBA-to-USBC power cable: to power the Pi from the USB port of the battery of the solar power station. Because in this build the Raspberry Pi is in a separate box, the power cable is best one that is waterproof i.e. not braided but has an entirely plastic sheath.

Build steps for the solar power station

1. Note the safety advice above. Use insulated gloves and insulated tools when working on, or around/near, the battery.
2. The battery is connected to the Victron SmartSolar solar charge controller device according to the very simple and clear instructions that come with it. The same goes for the optional SmartShunt and optional Smart Battery Sense devices. The solar panel is wired to the SmartSolar solar charge controller device according to the instructions with the device, making sure to wire the correct polarity. The bear wire connection points are screw terminals that require considerable force to ensure the wires are held firmly and do not pop out when manipulated. For this, using exaclty the right size screwdriver head is a good idea.

Build steps for putting it all together

1. It goes without saying, so I will say it, that this build is not suited to mounting above a public place where people may pass, in case something falls off from on high onto innocent bystanders.
2. The solar power station box is best not put in the shade behind the solar panel in winter (not as shown in the images), because that stops the box and battery therein from warming up fast on a cold winter's morning, which is not good for battery longevity. In winter, put the solar power station box in a sunny place next to the panel.
3. Test the solar power station setup, using the Victron apps, during the day to see that the solar power station is charging. There are some settings you need to set concerning the voltage of the panel and/or battery. Persuade yourself that the solar power station is working.
4. Test the rnode works when the USB C cable from the rnode, coming out of the collapsed spiderbeam, is plugged into the powered Pi. This test can be run most comfortably using a smaller temporary/test battery with USB C output, such as an Anker 737 which can run the Pi for at least 12 hours, and that battery also usefully tells you the power being used. This test requires a screen, keyboard and mouse to be attached to the Pi; alternatively a connection to the Pi over wifi/LAN cable can enable use of a browser to get access to the MeshChat GUI for testing. For running the meschat GUI via a browser, see Pi installation instructions. Check the node has the correct settings as you wish for your purpose (name, interface settings, transport node, gateway, propagation, announce time interval, etc.) and that it is working. 'Working' at least means its announces can be seen by other nodes e.g. another test node of your own, and that it can send and receive messages to another rnode known to be itself working correctly.
5. Test that the node works when the LiFePo4 battery's USB output is used. The LiFePo4 battery used here has a switch on the USB output, which needs to be switched to on.
6. If you haven't already done so, put the 3M tape around the edges of the rnode box/housing to waterproof it.
7. Mount the spider beam in an extended form. Pull the parts very firmly together to make a good friction fit to prevent the spiderbeam from collapsing suddenly during the process. Fix properly to a mounting e.g. the balcony railings using very robust cable-ties in sufficient numbers, or whatever solution works. Re-test the node is working using e.g. the Anker 737 battery.
8. Place the spiderbeam onto a block with a slot so that that the USB C cable can exit the spiderbeam without being cut or pressurised by the spiderbeam. Attach the USB C cable from the bottom of the spiderbeam to the USB A port of the Pi using the USB C to USB A adaptor.

9. Run the USBA-to-USBC cable from the battery's USB terminal to the USB C power input of the Pi.
10. Ensure all wires exit and enter the relevant boxes in a waterproof manner.

11. When everything is working, apply the cable conduit to keep the cables organised and neat.

12. Protect the solar power station box in a fetching bin bag, and the job is done.

13. Reticulate!

Last edit 03-07-2025 MMDDYYY 12:00:00 EST