I need help on designing my solar power setup

[timreichhart]

Hey Guys
I needing some help on setting up a complete off the grid power for my wisp at a water tower that does not have any power to it and I currently live in ohio.

here is the devices I am trying to power up.


Ubiquiti Rocket M2/M5 and the max watts of power they use is 6.5 and here is a pdf of the product:

http://ubnt.com/downloads/datasheets.../rm_ds_web.pdf

I will be powering up to 12 of these rockets if I needed 2

Then I will be using Ubiquiti Nanobridge M5 and the max watts used is 5.5 here is the pdf for this product: http://ubnt.com/downloads/datasheets...nbm_ds_web.pdf

I will be powering upto 5 of these devices

Then I will powering up a 24 port Ethernet switch and a Mikrotik 450G on this also.

This will be my only power source for 24/7/365

Thanks Tim

[Mike90250]

Wow ! Ambitious project ! I'll first figure out how much PV & battery you need for 24 hours. But you have to reply and tell us how many days of cloud cover, you need to allow for, and the penalty for shutting down. I predict, you will need a auto-start genset ($6K) to avoid a huge PV & battery investment ($20K)

Rocket 6.5W x12 units =78w
nanobridge 5.5W x5 units =27.5
24 port Ethernet switch ??? 20W
Mikrotik 450G 10w
total load: 135.5 w Lets round up to 150W, to allow for margin. Now if these all have wall wart power supplies, or take different voltages, we have to allow for at least 30% losses in the cheap crap supplies that come with the parts. I'm NOT adding this in yet, its another unknown . I see the Mikrotik can run PoE 18-28V, this may be a good case to run right off a 24V battery, except recharging can hit 30V dc, may need to use a good, efficient DC-DC converter to power things with

150W x 24 hours = 3,600 watt hours.
for scale, a large deep cycle boat battery (group 27 size) can hold about 100AH @ 12V, or 1,200 watt hours, if drained completely. Drain to 50%, a battery may not even last 1 year (365 cycles) so we can only allow daily drain of 25% to insure at least a 2 year life.

Will you be able to do monthly maintainance - add water to batteries and such? Or do you need complete un-attended operation ? (un-attended add $$$3x for AGM batteries)

So, 3,600 watt hours x 4 = daily battery capacity =14,400wh, round up and call it 15KWh. Yow !

48V battery @ 400AH = 19200wh,
48V @ 375AH = 18000wh so this looks like a manageable battery (FOR one DAY)
That's 8, 6V L16 size batteries, and this class of battery, should last you 5 years before needing replacement. only about $400 each. $3,200 for the bank, and add more in for interconnects.

To recharge this bank, in 4 hours of winter sun, you need (wait for it .....)



7,500 Watts of PV. Round that up to 8KW, and you will be very close to right on.
This is for 1 day backup. Double for each additional day, if your batteries are low, and you get 1 sunny day, you need to recharge them ASAP, in that 1 day of sun. Makes that backup genset look pretty good, depending on your area's history of cloudy days.

Sure there is no way to get utility power to the site ?

Even microwave power beaming may be less expensive then this huge solar system!

[timreichhart]

Well Mike
here is other ways getting power to it since its in town and I would have to pay electrician any where from 1k to 3k just line installed then pay the power co 10 dollars for meter rental plus useage. I have been talking to some other people on ubnt forums and they told me I can use 4 280 w solar panels with 6 toyo deep cycle battery @ 120 ah. They also told me I can do DC to DC setup but I dont know about that yet.

I also reworked my configuration to get it down to 107.5 W.

I was just trying to figure out which way its going to be cheaper on doing this setup.

[Sunking]

Well Mike
here is other ways getting power to it since its in town and I would have to pay electrician any where from 1k to 3k just line installed then pay the power co 10 dollars for meter rental plus useage. I have been talking to some other people on ubnt forums and they told me I can use 4 280 w solar panels with 6 toyo deep cycle battery @ 120 ah. They also told me I can do DC to DC setup but I dont know about that yet.

I also reworked my configuration to get it down to 107.5 W.

I was just trying to figure out which way its going to be cheaper on doing this setup.

Based on what info you have provide pay the utility. Even at 107.5 watts works out to 110 watts x 24 hours = 2640 watt hours so whoever told you a 1120 watt panel setup would work obviously does not know what the heck they are talking about.

Secondly at the power levels you will require a minimum 24 volt battery setup, 12 volts is not going to work as it will only add a lot more cost for using 2 charge controller.

Where is this going to be located. Just based 2640 wh per day I can guarantee you it will cost at least $7000 to $10,000 initially plus another $2000 in 5 years to replace the batteries. So with that said the utility is one hell of a bargain

[russ]

Hi Tim - As Sunking pointed out, there is far more bad information on the internet than good.

Whoever said 1120 watts of panel is talking rather than thinking. If it is a full battery operation you would need to have a generator to support the system and charge the batteries in the event of several days with too little sun - otherwise you will be damaging expensive batteries.

Mike and Sunking will be very close on this type of thing.

Russ