Powering internet with solar

Hi
I have just installed a Ubiquiti NanoStation M5 antenna as part of a citywide mesh infrastructure for having a parallel users owned internet system (as in here).
I'd like to power this NanoStation with solar power if possible but at the same time I would probably need to switch to grid power in case the sky is clouded or at night (in case I decide not to use a battery).
What would be the best way to do so? What kind of solar PV panel do I need and how to connect the output of the solar cell to the antenna.
The antenna has a 24V input 0,5A, 8W as max power consuption. The power reaches the antenna through an ethern cable (RJ45) that in turn goes to a POE adapter which is powered by the grid. The POE adapter has another RJ45 slot where the ethernet cable from a router enters. So the PV circuit would need to use a similar arrangement but probably with a different type of POE adapter. There would probably need a POE cable going from the PV panel to the antenna and another POE cable reaching the AC POE adapter as well the two latters would be connected to a "T" switch of sorts, which decides where the power comes from....not sure if something like this even exists.
Has anyone done something similar or can suggest a possible solution?
Cheers

If you are looking to offset the energy of the device then it would likely be cheaper and more efficient to use the solar panel with a grid-tie inverter. If you have reliable grid power available then it would be extremely beneficial to go grid tie.

A quick look at their community page shows people with a lot of first hand experience doing similar things with their products:
https://community.ubnt.com/

It goes well beyond the scope of what most people here are doing with electronics, and there will be a lot more people there with the same hardware that can point you in the right direction.

I found this to be interesting. They are for security systems. Grid tie would be the least cost option and efficient, still a battery for backup is nice, especially for comms. Also there are ac auto transfer switches that prioritize battery/solar use for about a hundred dollars, but they require a battery and inverter.

https://www.barcodediscount.com/catalog/altronix/part-al125ul.htm?aw&adtype=pla&gclid=EAIaIQobChMIgcncp73F2gIVRlcNCh0hLAH_EAQYCCABEgJMDPD_BwE&gclsrc=aw.ds

https://www.wolfautomation.com/index.php/catalog/product/view/id/8908/s/ups-battery-back-up-24vdc-40-amp/?gclid=EAIaIQobChMIgcncp73F2gIVRlcNCh0hLAH_EAQYAyABEgKvVPD_BwE

http://www.maglocks.com/catalogsearch/result/?q=power+supply+battery+backup&x=0&y=0

http://tycononline.com/UPS-PL2448HP-9-UPSPro--24V-Battery-24V-PoE-Backup-System--Solar-Ready_p_271.html

https://www.balticnetworks.com/tycon-power-kit-ups-pro-60w-backup-power-system-poe-powered-steel-encl-24v-51ah-gel-battery-4-switched.html

http://www.bturesearch.com/ups-poe-injectors.html

https://www.securityworldmarket.com/int/News/Product-News/high-power-poe-injector-with-battery-backup-controller1#.WtgeenTD-BY

https://www.rowewireless.com/12v-in-48v-out-poe-solar-charge-control/?gclid=EAIaIQobChMIpIuJ5sTF2gIVm4izCh3a3gXPEAQYASABEgKWNfD_BwE

I dont know of a system designed to not have a battery and switch to a power supply when solar input is insufficient.

Frank, Daniel, many thanks for these pointers. I'm gonna look into them

frank li wrote:

I dont know of a system designed to not have a battery and switch to a power supply when solar input is insufficient.

Hi Frank,
do you mean that the battery needs to take over even if only for a few seconds that it takes to do the switch from solar to grid/and viceversa?

Yes and no. Im sure there is a device or collection of devices that could do it, ive just not ever seen one.

The battery is needed to keep the inverter and charge control on and the battery takes up slack and dampens electrically. If the idea is to power the load on solar is one thing and to back up the grid is another. You can have a grid tie with backup and solar easily, ac or dc or you can set it up with grid power as backup. But again, if your goal is to have solar in the mix and comms want to be up at all times, a battery inverter with a grid charger or the dc power supply/transfer/chargers would work great and the comms power supplies have solar inputs already for $65!

The 5 links at the bottom of my previous comment are the network comms equipment, i think four of them have solar inputs. They will supply regulated, adjustable dc as POE injection. I did not read deeply into features and specs. Im sure you can find a nice off the shelf solution if you use the terms scattered through the links.

Hats off to setting up some mesh! Hope it goes solar.

Solar priority transfer switch.

http://spartanpower.com/product/spts450012/

I can't imagine a good solution for this… You don't happen to have a 24V grid around?

At 8W · 48h ≅ 400Wh you will need a significant battery to even power it for one [day, night, overcast day, night, day] cycle …

It would require:
- at least 400Wh battery (capable of running at freezing temperatures to 40°C?)
- solar charge controller to protect the battery against over- and undercharge
- 24V power supply that also feeds the charge controller
- balancer for the battery, in case it isn't lead-acid.
- 100W solar panel (or more? depending on the average sun in winter)

But then the problems are just beginning… Do you prioritize
- a full battery and use the grid when there is no sun? (so if the grid does down, it runs longer)
- a half-full battery for extended battery life? (even shorter runtime)
- maximum use of the solar panel? (less battery life and shorter runtime if the grid goes down)

Personally, I would use the 24V power supply that comes with the device and run a cable to it, in case you decide to build an 24V off-grid system.

Sebastian Köln wrote:I can't imagine a good solution for this… You don't happen to have a 24V grid around?

At 8W · 48h ≅ 400Wh you will need a significant battery to even power it for one [day, night, overcast day, night, day] cycle …

It would require:
- at least 400Wh battery (capable of running at freezing temperatures to 40°C?)
- solar charge controller to protect the battery against over- and undercharge
- 24V power supply that also feeds the charge controller
- balancer for the battery, in case it isn't lead-acid.
- 100W solar panel (or more? depending on the average sun in winter)

There are links to very well designed and off the shelf solutions in my comment above!