Electric "can" be more cost effective unless you have to run wires a
half kilometer or more. Our first remote POP was not quite a 1/4 mile
from the nearest electric source, so we had to trench that distance, run
conduit, and run relatively large gauge wires that distance. At that
time, the cost of the copper alone exceeded the cost of doing it in
solar. Today, the cost of the solar is a fraction of what it was then,
and LFP batteries are now cost-competitive with SLA batteries.
That all said, we are at a convenient latitude (37°), and we have a
pretty moderate climate, so heating and cooling are not a consideration,
and we get at least 6 hours of sun on the shortest day of the year.
bp
<part15sbs{at}gmail{dot}com>
On 8/15/2023 9:38 AM, [email protected] wrote:
I can save you the suspense. If you have access to electric that’ll
be cheaper than solar. The problem is the need to run 24/7. You have
to design around the December-January months. I’m in NY State, and at
our latitude we only get a few hours of average production per day
during those months. And obviously if it’s snowing for a week you
need to be able to ride through that on mostly battery power. Even
with a modest load it takes a silly amount of panels and batteries to
stay up 24/7 in the winter. More than you’d ever be allowed to put on
a utility pole.
Talk to your electric co about the smallest service you can get.
Explain what you’re trying to do and that your max load is very low.
NYSEG normally doesn’t do less than 100A, but they made an exception
and let us do 60A. You need a meter can, a service rated panel, a
conduit up the pole and a weatherhead. Then you either have an
outdoor outlet, or have an outlet inside your enclosure. You’ll want
the smallest service they’ll let you do because of the wire size on
the service cable. A 20A (if they’d allow it) would only need a 12/3
with ground, and that’s up to 4800 Watts (240x20) so it’s still more
than you’d ever need. A 12/3 is way cheaper than a 100A service
entrance cable.
My figure is 8 years old, and obviously there’s been inflation since
then, but I went to the same contractor who does electric installs for
the cable company and they quoted me about $1000. Even if it’s 3x
that for you today you’d still never beat that with a solar
installation even if they’d let you do it. And I’m not some knee-jerk
anti-solar lunatic, I’m just saying I’ve run the numbers and it
doesn’t add up. People do it when they’re off grid, or when the
electric service is unreliable in the area, or sometimes just for the
PR/marketing power of being “solar powered”. Those are all fine
reasons, but doing it for cost savings isn’t going to work out.
-Adam
*From:* AF <[email protected]> *On Behalf Of *Steve Jones
*Sent:* Tuesday, August 15, 2023 10:27 AM
*To:* AnimalFarm Microwave Users Group <[email protected]>
*Subject:* Re: [AFMUG] battery nerd question
we have a dozen or so, but are looking at pole mount micropops (our
own poles). We are losing a grain elevator site because they
decommissioned the elevator and theres no real options for the
customers in some of the areas. Im just trying to get to something we
can get solar power with enough battery to last through overcast. So
Im calculating per battery runtimes, then will look at number of
batteries we would need to survive vs paying for a ROW meter vs losing
the customers. Just have to get to the cost per customer to retain
them and the benefit gained per pole
On Tue, Aug 15, 2023 at 8:53 AM Brian Webster
<[email protected]> wrote:
How many of the batteries do you have? Do you need any voltages
other than the 48 volts? If you have 4 batteries and only need 48
volts then wire them in series and not have to deal with the
converter.
Thank you,
Brian Webster
*From:*AF [mailto:[email protected]] *On Behalf Of
*[email protected]
*Sent:* Tuesday, August 15, 2023 6:59 AM
*To:* 'AnimalFarm Microwave Users Group'
*Subject:* Re: [AFMUG] battery nerd question
*You’re around C/30 which should be on the high end /of capacity/.
Lower load usually means a little extra capacity out of the
battery. I realized that sentence might have been ambiguous.
*From:* [email protected] <[email protected]>
*Sent:* Tuesday, August 15, 2023 6:56 AM
*To:* 'AnimalFarm Microwave Users Group' <[email protected]>
*Subject:* RE: [AFMUG] battery nerd question
You can do the whole thing in Watts.
12V * 150ah = 1800 Watt-hours
1800Wh / 50W = 36 hours
If they’re telling me 95% efficiency, I’d assume 50W out needs 53W
in (50 / 0.95).
There’s usually an efficiency curve for the device based on load
and temperature so it wouldn’t be 95% in all circumstances. Your
system should be drawing less than 5A off the battery, and if your
multimeter has a 10A fuse like most do, then you could put the
meter in line and actually measure the amperage before and after
the converter. Then you’d know for sure.
And the battery’s total capacity will have a curve based on C-rate
so there’s some variability there too. Usually it lasts longer
when you’re drawing lower amperage. You’re around C/30 which
should be on the high end.
Age and maintenance of the battery affect runtime as well. If I
want 6 hours of runtime then I plan Ah for 12 hours runtime. When
my batteries are halfway toasted I’m still getting useful life out
of them.
*From:* AF <[email protected]> *On Behalf Of *Steve Jones
*Sent:* Monday, August 14, 2023 9:57 PM
*To:* AnimalFarm Microwave Users Group <[email protected]>
*Subject:* [AFMUG] battery nerd question
Just trying to cipher runtimes
I have on hand 150ah 12 volt batteries, so thats what id
be looking to use.
Excluding the conversion loss of a 12v to 48v step up converter is
the math correct here?
12v 150ah=1800 watt hours
1800 watt hours at 48v = 37.5ah
50 watts of radio running 48v = 1.04 amps
37.5ah @ 1.04 amps = 32.77 hours runtime
does a step up that claims 95% efficiency mean 95% of the watt hours?
--
AF mailing list
[email protected]
http://af.afmug.com/mailman/listinfo/af_af.afmug.com
--
AF mailing list
[email protected]
http://af.afmug.com/mailman/listinfo/af_af.afmug.com
