[ANSS-netops] solar power problems

[Kyle Persefield]

Mitch,

My 2 cents worth

Because of cost, we have found throwing on more solar panels to be the
cheapest and least maintenance intensive solution.  Fuel cells and
thermoelectric generators are expensive and then there is the recurring
cost for fuel, getting fuel to the site, then monitoring of the fuel
supply level to consider, and the added required maintenance.  We have not
found a solution to use these devices as demand requires their use.  Or
turning them on and off as needed.  So long as there is fuel they are on.

We have been very disappointed with wind turbines.  The smaller ones,
which are designed for the consumer market, the bearings always fail.
Expect no more than 2 or3 years out of these "cheap" units.  Then of
course there is the need for wind.  No wind for extended periods is just
as bad as your overcast scenario.

Kyle

-----Original Message-----
From: ANSS-netops [mailto:anss-netops-bounces at geohazards.usgs.gov] On
Behalf Of Mitchell M Withers (mwithers)
Sent: Monday, January 05, 2015 7:12 AM
To: Philip Crotwell
Cc: anss-netops at geohazards.usgs.gov
Subject: Re: [ANSS-netops] solar power problems


Here is a snippet from a recent report from a visit to an example station
with a reftek, three S-13's, and an episensor.  Stations vary of course
and we do use low voltage cutouts at every station (fancy ones that cut
out the transmitter first, then the DAS and everything else if the voltage
continues to get lower).

"The new battery banks, when installed were at 12.95 and 12.98. The total
station draw is exactly 600ma (checked continuously for about three
minutes). I did a quick calculation of 4 batteries at 96AH each, 384/.6 =
640/24 =26.6 days. This calculation would assume no solar charge, but does
not take into account reduced battery capacity due to cold temperatures."

The panels at that particular station were supplying about 700ma together
on an overcast day and are being replaced with bigger panels this week.
Of course one solution is more battery and more solar at every station
along with more frequent refreshing of batteries.  But that gets expensive
and time consuming so I was fishing to see if anyone is doing something
creative. (e.g. wind or hamster wheels).

Mitch

Center for Earthquake Research and Information (CERI)
University of Memphis                Ph: 901-678-4940
Memphis, TN 38152                   Fax: 901-678-4734


________________________________________
From: Philip Crotwell <crotwell at seis.sc.edu>
Sent: Monday, January 5, 2015 7:50 AM
To: Mitchell M Withers (mwithers)
Cc: anss-netops at geohazards.usgs.gov
Subject: Re: [ANSS-netops] solar power problems

Hi

How did you come up with your 25 day figure? Can you put some numbers on
power input and output?

We use two 105 amp-hour batteries per station, where the load is about
1/2 an amp. That gives me about 17.5 days theoretically, but my
understanding is that you never want to discharge batteries anywhere near
their rating as they can be damaged by high discharges. So maybe worry
less about age and more about installed capacity, ie double the battery
and replace them half as often.

We also, because of the cell modems, can monitor the battery voltage over
time, we have a cron job to ping the cell modem once an hour and ask it
what the input voltage is. For example here is the last few days at one
station. You can definitely tell the difference between sunny days and
rain, and we get a heads up if the power is getting low and can do
something before the station goes down.
http://eeyore.seis.sc.edu/earthworm/status/HAW_last720.png

Here is another station that we are becoming worried about, looks like I
might get to go on a road trip soon!
http://eeyore.seis.sc.edu/earthworm/status/CASEE_last720.png

Philip

On Sun, Jan 4, 2015 at 9:07 AM, Mitchell M Withers (mwithers)
<mwithers at memphis.edu> wrote:
>
> Many of our stations run on battery and solar and that normally works
well.  We have a routine battery replacement cycle to make sure they don't
get old.  Theoretically, we should be able to run with zero solar for
about 25 days.  But this has been an unusually dreary winter in the
southeast and we haven't had much sun for the past two months or more.
I'm wondering what others do in areas with limited sunlight to power
stations that don't have AC available?
>
> Mitch
>
> Center for Earthquake Research and Information (CERI)
> University of Memphis                Ph: 901-678-4940
> Memphis, TN 38152                   Fax: 901-678-4734
>
> _______________________________________________
> ANSS-netops mailing list
> ANSS-netops at geohazards.usgs.gov
> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
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