solar sites

is anyone using a fully solar powered AP site?

if so whats your setup and reliability like?


I know of one company in Alberta that had to use solar power at there tower site because the cost to get a power line trenched to the tower was well over there budget and way to long of a wait.

Last time I talked to him he hasn’t had any problems with it at all.

He is using a combination of solar and wind power in order to power up 6 AP’s, a CMM, and a backhaul.

we have 2 solar/wind powered sites and they run better than our electric powered sites. if we have to set a transformer to get electric to a new site then it is cheeper to just set up wind/solar.

typical canopy/network equipment we have at the sites include a 5210BH20, a CMMmicro, 5750AP a router and a DABin (from to monitor via snmp the solar/wind and battery systems) We have enough extra power to fully load the cmm with AP’s as the customer base grows.

we use good prices and they have a great staff. i can give you our specs. for our system but you really need to run the math for your part of the world. we designed ours to be fully sufficient thru the darkest days of winter on solar power only and then added the wind generator as gravy on top. We get an average of 400" of snowfall in the winter and the towers are in remote parts of the colorado mountains so we wanted both wind and solar to ensure 100% uptime. in addition you may get a tax credit for your set up.

(just an FYI i contacted and they designed a system that had the solar panels mounted to the ground, if you didn’t notice earlier we get 400" of snow per year…not a good place to mount your solar panels. maybe it was just the sales guy i spoke to but that made me look elsewhere.)

sunwize wanted 12k for my specs. we decided it would be cheaper to run 1000ft of power cables, pay for the labor and put one hell of a UPS up there and it would be cheaper.

to power the equipment i mentioned in my earlier post we spent around $3,000. which like i said is less than setting a transformer etc. and we have about 4 days of runtime should there be no sun or wind.

sunwize quoted a system around $10k-$12k for us too in addition to wanting to put solar panels on the ground where they’d get covered with snow! they advertise as a canopy solar solution provider, but i think it’s just a marketing ploy.

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I had two mountain top sites using Solar power and another using Air-X wind generator.
Forget about the Air-X wind generator, Unless you want to fix it every 3-4 months.

Utility power is now available and I made the mistake of switching.

Using solar power was very good.
I had 12, 50 watts panels and a OutBack MX60 MTTP regulator to regulate the Power.
To monitor the battery voltage I still have a Omnitronix SL60.
To maintained the voltage over night and on cloudy days I had 8 Trojan Batteries.
At that time I was using 4 radios (100 Watts), now I have 8. But the new canopy radios consume less then half the power of my older units. ( 9 x 8 = 72 Watts ).

You might thing 12 solar panels is too many but this is the most important thing to keep in mind.
One must calculate how much time you have for solar power to be collected.
I’m down in the Caribbean and I only have 4.5 hours.
Calculation is
12 solar panel @ 50 watts each = 12 x 50 = 600 watts per hour.
600 watts x 4.5 hours = 2,700 watts per day.

2,700 watts / 100 watts = 27 hours.
In other words I had 3 hours per day as spare o 300 additional watts per day. In case I had a week of cloudy days, I had to go up with a portable generator.

The best part was I never, ever, had Lighting of voltage spikes, now I do.

Hope this helps.

so let me get this right. if i where to use a 900 sm to feed a 900 ap that would be 7.2 watts per module assuming i use a cat 5 barrel and did not use a switch.

that would be 14.4 watts.

now if i get 2 80 watt BP solar panels that would be 160 watts assuming i had 5 hr average sun that would be 160x5=800 wh then 800’14.4=55hrs
then use say (4) 6 volt gels batteries in series = 24 vdc then feed the sm and ap direct dc with no inverter.

would that be sufficent?



Before I get into the solar power stuff. According to Ben, at Motorola It is not a good practice to use a 900MHz AP and a 900MHz SM on the same site. The reason is that they will interfere with one another. And you can not sync the AP with the SM.
My advice would be : You could try this but YOU MUST INSTALL a band pass filter. In this case your output power would be less. Hope that works!
Best thing to do would be to install a 5.2, 5.8 uplink.

Now about the solar power.

First you should calculate 8 watts, ( round this up in alternative energy )
Second you should calculate the loss on the regulator. ( In my case I had a 5% loss because I was using MTTP regulator). I don’t think you will find a MTTP regulator for 160 watts. Normal pulse regulator are about 80% efficient. That’s 32 watts less of power.
Then 128 * 5 = 640 Watts per day.
640 Watts per day / 16 = 40 Hours of power using 16 watts continuos.

The Trojan battery I use are rated at 220 amps. If you use 4 of them you will have a maximum power 5,280 watts / 16 watts = 330 hours / 24 = 13.75 days = 1.96 weeks. with out any sun power. Remember, batteries must be in warm place 75 - 90 Degrees.

But in general, yes that will be more than sufficient.

contrary to motorola Ben’s belief, you can sync an AP with an SM, it is still better than having it generate it’s own sync.


How can I put a SM to generate sync using hardware scheduling ?

What will happen if the AP feeding the SM-AP is transmitting at the same time the SM-AP is ( If it’s possible ) ?

and last

Is the SM, and AP capable of filtering/discriminating in band transmissions ( Carrier to Interference ratio @-3db )?

I have did this several times i only do it for places that i dont intend on putting more than say 20 customers.

here is how i do it main ap is generating sync the sm recieves it then i make a jumper plug to go from sm straight to ap which is set to recieve sync without using any cmm. So i am actually synced to the main ap however i use a different freq on the remote ap.
But i do recieve with vertical pol and send back out horz. but i still try to keep the vertical separation at a good distance.

anyways are you saying that 2 80 watt solar panels are not enough?

Yes, 2 solar panels is more than enough.

About the link, If you do a SM with a AP on the same tower you will have a high re-transmision of data packets. It will work, but please look at the stats.


kmeadows is correct, I have seen people do this on the same freq band and polarization, but you have to have your channels spaced properly and put some horizontal and vertical seperation in between the two of them to avoid any conflicts in RF and it is best that the remote AP does not point in the same direction as your main site to avouid any issues.

As to the number of people you put on this AP, it depends on their throughput needs. I on stadard canopy SM and AP, and the SM was also feeding a NLOS orthogon link for a remote community, remote site feeding approx 50 people, but this too many on this link and I needed to put a backhaul up as packets started to be dropped and speeds went to a grinding halt. I would not go above 20 users if your using 900 AP’s and SM’s, if using an advantage 5.7 or 2.4 and 900 as a remote you could probably get away with 30 to 40 people, I would not want to go much more than that without putting up a backhaul. :stuck_out_tongue:


Vince is using the 900 MHz spectrum only.
The C/I on the unit is 3 db. The separation rules on 900 MHz on the same tower do not apply. The 4 Watts EIRP is high power in 900 MHz with out using any filters.

I would agree with you if Vince would use different spectrum.

But that’s just my opinion.


Seperation rules always apply on frequencies. For example if I use a 900Mhz OMNI horizontal link at 906 to feed a AP OMNI or panel that are horizontal running at > 915, in theory and in most real world apps, I could run this systems without causing interference between any of the 900mhz links on these 2 towers. This is always pending on what the noise floor is at in those areas.

I have done this with 5200AP and 5200SM combined together as well as 9000APC and 9000SMC, just keep enough seperation between the units, if on a tower I try to keep at a minimum 20 feet(30-40 feet if 900mhz, if I can get away with it) and have them facing somewhat opposite directions, on buildings opposite corners of the roof seem to work OK. Just remember to space frequencies apart with enought of a buffer zone so that they don’t bleed into each other.

Guys at tech support are good for some questions, but there are some things that help desk just does not know, that is not in the manual. Don’t get me wrong the manual has a lot of info in it, but if I had to read a manual for everything that I setup or did in when it comes to RF I would be reading manuals and talking to tech support for a very, very, very long time…

There is no substitute for experience, as with most things in life, not everything is in a manual. :lol:


The repeater in question is in the same tower, no on two remote tower. Two radios in 900 MHz, powered form the same 24 volt, solar panels, power system. ( The distance on the wires can not be to long)
Say he has one on 906 and the other in 924.
In the same Tower Vertical or Horizontal Polarization will be the same, the for these 2 radios because they are so close one from each other.

I not talking about the other remote tower.

He wants to have 2, 900 mhz radio, heck you can have 6, 900 MHz radio but they must all be AP. In his case he wants one SM that’s receiving the sync from a remote AP, who knows how far. The local AP will be generating it’s own or a GPS sync. The problem is what should he do with the SM :
1) It’s out of sync with the local AP,
2) Will receive high power transmission from the AP in the same tower,
3) The two are in 900 MHz.

If he would be in 2.4 or 5.8, he will not have any problems, but he is using 900MHz, where the spectrum bandwidth is 8 MHz and not 20 Like the others. And other technical difference.

it will still work. cause i did it but i have a real low noise floor i separated the frq’s at 906 and 924 both on horiz and i only had about 20 foot vertical separation.

i used a 900 sm with 14 db yagi then fed to 900 ap omni 20 foot above with sync cable and it work ok but i did find out real quick to uncheck all the freq’s not need in each module. cause when i first put it in the sm was regestered the the ap right above it LOL.

But anyway i ended up taking off the sync cable and generating its own i got away with it for about a year. Then i had to do a back haul cause i got to many on it.

oh and they was only 2 miles apart you could see the towers. Dont get me wrong this is not the way to do it for ever. its just something to get you over the hump in my opinion.