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Solar powered nodes - how do you power your antennas?

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Solar powered nodes - how do you power your antennas?

a question for those who run solar powered nodes - how do you power your antennas, what's the best way as per your experience?
  • with 12Volts directly from battery (as long as the devices are supporting this low voltage)
  • with 24Volts directly from two batteries (in series)
  • with 24Volts, from 12V to 24V up-converter
  • with 24Volts, from original POE injector connected to a 12V to 110V AC converter (most unlikely i guess)
  • others?

And, as per your experience: to ensure the re-charging of the battery even during a bad weather period, what's your solar panel configuration?

Thanks a lot!
nc8q's picture
My solar power setup
Hi, Kurt:

You are likely interested in a rooftop or portable setup.
Here is my home solar power setup:
Images of solar-panel, 2x 100AH 24 volt batteries (5160 WHrs), AIO-controller.
Node: Ubiquiti Loco M2 XW (2GHz access point)
Switch: Netgear GS-108Ev3
Raspberry-Pi MeshChat
Raspberry-Pi MeshMap
Raspberry-Pi Teamtalk
Raspberry-Pi LAMP server
x86 Linux laptop (
VoIP Phone (MeshPhone 937-1000)

73, Chuck

Image Attachments: 
Nice Chuck!
Nice Chuck!

I'm very curious how you like the Ampere Time batteries, they seem to be "higher end Amazon" but I've held off putting $ into more batteries. 

Re the questions from Kurt ...

Run your nodes at 24VDC.  Why would you deliberately undervolt something, even thought it says you can?

Here in Oregon, my rule of thumb is that my solar panels can only be depended on giving 10% of rated power and only for 6 hours a day during the overcast winter months.  We have two seasons, winter and August.  A ham friend told me he believes it is only 5%.  Summer sure, you get lots of power but is your charge controller large enough to grab the watts when they are available?  OVERSIZE everything.  Now if you live in Texas or California your results may vary.  Just beware ...

Your batteries and charge controller must match.  Other than than it really doesn't matter if your battery is 12V or 24V.  More stuff exists in the 12V world fwiw.  The 12-24V boost converters can easily handle the power requirements of your AREDN nodes and most DC power supplies expect 12V anyway so my stuff is all 12V batteries.

AC power is not something I advise at all.  You have power losses every time you use a inverter, and these losses can be quite large over time.  You radio and mesh devices are ALL DC inside, why run any AC wall warts?  You go battery DC to inverter to AC, to wall wart back to DC to put into your equipment.  Ugh.  AC is only useful if you must run a household appliance like a refrigerator.

nc8q's picture
how you like the Ampere Time batteries
Hi, Ed:

I have nothing to compare. I am satisfied, though.
They work together.
1st 24V 100 AH was pruchased from Ampere Time in October 2022.
2nd 24V 100 AH was purchased from Li Time a few months ago.
I managed to get them both at the same voltage, then I connected them in parallel.
I plan to switch the nodes from wall wart to battery soon.
I will be leaving the laptop on 120 volts AC.
I may consider getting a 24V to 5.2 Volt converter for the Raspberries.
I'd need one more converter for the VLAN switch and 16 port switch.
I think Ubiquiti and Mikrotik will accept 28 VDC max.
I'll set the charger controller to 28V maximum.
Currently the setting is 28.2V.

73, Chuck

KE6GYD's picture
How we Power relay nodes
We have three hilltop nodes that act as relays to a central location.  To power the Ubiquiti and Mikrotik nodes at 24v, we use a Netonix WISP WS-8-150-DC
switch.  The switch will take input voltages from 9 to 72 volts DC.  Ports can then be configured to provide PoE of 0v, 24v, or 48vDC.
Thus, any 12v source (Power supply, solar charged batteries, etc.) can be used.   These switches, while not inexpensive, have been very reliable and in use for over 4 years in Southern California in a relatively hostile environment that can get quite warm in summer and down to the high 30's in winter.

The switch web interface also has ability to show a 24 hour graph of the input voltage.  Comes in handy when evaluating how your solar charging is doing.  We also use a RasPi at the site to interface with the Solar Controller so we can see it's charge voltage, current, etc.

Image Attachments: 
KE6GYD's picture
This relay node site uses 4
This relay node site uses 4 100watt 12v panels wired in banks of two.  Two panels in each bank are in series.  Then we parallel each bank to each other.
We use a Renogy 100Ah LiFePO4 battery.  This site only runs on solar.  Three nodes, the switch, Pi, and a camera draw about 2 amps.  The system seems to handle 3+ cloudy/rainy days.  Any more, we turn off the camera to save a little power.  For less sun, probably should go with a few more panels.
We use an EPEver 30 amp MPPT controller.  Has an RS485 output that goes to a RasPi.  The Pi has a custom program that can monitor the solar controller's solar input, battery charge, load amps, etc.
Hi Kurt,
Hi Kurt,
Great questions.

Here is what I am testing for an easily deployable node.  This is in testing stages so will probably change.

Physical configuration is a short metal tripod with short pvc mast topping out at 60" with 2 MikroTik SXT nodes.  This functions as bridge point between 2 towers blocked by a large water tower.  Again this is experimental at this point and will be tested with 3 nodes at some point.  Location is intended to be uncluttered field location with line of sight to the horizon so minimal foliage.

Power is a 20A 12vdc Bioenno LiFePO4 battery (with BMS) with 60watt RichSolar panel for recharge.

Solar controller is MPPT 20A by HQST ($83).  This controller comes with a temperature probe.  It has a BlueTooth (BT) smartphone app that is a nice monitoring function but range is pretty short (20ish feet).  This unit may be over spec'd but feature set is good since it works on 12 or 24 volts and can store some data for over 200 days.

The battery is connected to the solar controller which has a remotely (BT) switchable "load" function capable of supplying the load of the nodes (5 -7 watts).  Solar connection is optional depending on the deployment but my use is intended to operate long duration.

From the load terminals of the solar controller I have wired up a Cat 5 cable to pass the battery12v POE to a Ubiquiti NanoSwitch.  Power is depending on the battery but commonly 12ish volts.  MikroTik SXT nodes are good to 10vdc and seem to work ok but more testing is expected.  NanoSwitch seems to work and provides POE and dtd between the 2 nodes to bridge 2G and 5G. 

I think the 60 watt panel is iffy but should be sufficient for testing.  Either the panel or the battery could be uprated. 

This usage is intended to find the weak points.   It should be interesting.


*** Ben KE3KQ
That you are already aware
That you are already aware the solar panel and battery might need to be upsized is good.  It's good your charge controller is already oversized as you will find it is not actually too large, when the sun shines you want to capture everything you can.  Have fun testing!

Two things to consider ... one is that any solar panel is essentially a wing looking for enough wind to take off.  You can't deploy solar on a whim and leave it in place without thinking of how it will stay put which requires a lot more thought and guy wires/weights than a tripod of nodes.

The only thing in your parts list I would add is a buck/boost converter.  Nearly everything in the AREDN world works best on 24VDC and this converter inline before your power injectors means ANY battery you find lying around can work ... no matter the state of charge ... and it is a voltage stabilizer which is a good thing also

73,  Ed
Mentioning man portable use case
The focus of responses seems to be stationary/fixed nodes on buildings or towers.  In those situations large batteries and solar panels can be fine.  But another use case is portable operations for special events and emergency service, deploying nodes where they are needed or moving them around as conditions change.  For "man portable" operations it is simply not practical to use 24v batteries and large solar panels.  As Ed k7eok mentioned, you can bring a buck/boost converter to get from 8-40v to 24v, but all of the currently available node hardware has a built-in converter to run between 10-28v.  External converters are non-essential, introduce a point of failure, and add weight to "man portable" loads.  I don't know whether you are interested in this use case, Kurt, but thought I'd mention it.

Many thanks for your very
Many thanks for your very good answers!

My test setup currently consists of a 135W Panel connected to a 8A charge controller. For now it's a small 12V 7.2Ah AGM battery that's powering a LiteBeam via a 12V to 24V POE step-up converter. It looks like this is the minimum safe configuration to constantly run one antenna, the battery is charged even during cloudy/rainy days (we have lots of them, but at least we still have all four seasonssmiley)

@Bob KE6GYD thanks for the hint regarding the Netonix switch. This was completely unkown to me, and looks like a very useful device for some of our planned nodes. I'll check if it's available somewhere over here in Europe.

@Ed K7EOK: I'm completely with you re the 10% or less a panel delivers during cloudy days. I run a test using a 10W panel, which was working great during sunny days, but as soon as it got cloudy, it was like not existing anymore, like <1W of power was delivered - the charge controller didn't even recognize it anymore. Now with the 135W I'm at least at around 10W what is still enough for charging the battery.

Thanks a lot folks!



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