cellular pv site project [RE-wrenches]

[Bob Maynard, Energy Outfitters]

HI Keith,

I designed and sold several mountaintop cell site systems here in the
Northwest during the late 90's.  They were all negative ground 24vdc
systems.  Most of their equipment was dc with an occasional small ac device
which we powered by an Exeltech inverter.  The load profiles are typically
quite heavy, pretty surprising for electronic equipment!  Watch out for
equipment room ventilating/cooling equipment.  They greatly appreciate some
lighting circuits for the equipment room(dc or ac didn't matter).  If there
is an inverter, they like a couple of receptacles to plug in test equipment
when they're at the site working.  We normally used simple contactors for
charge control to assure we didn't generate any noise, although on the last
systems I used Trace C-40's with no adverse effects.  PV by itself could not
carry these systems by themselves in our climate.  We tried wind machines.
They were a nightmare with the harsh mountain top conditions, icing, wind
gusts, etc.  Virtually all ended up with engine generator backup, low
voltage auto start and large rectifiers.  Most sites used industrial
batteries, some wet, some sealed.  A few experimented with L-16's but to get
adequate amp/hour capacity required to many strings in parallel, leading to
problems.  Hope some of this is useful, feel free to contact me on or off
list.

Regards,
Bob Maynard
Energy Outfitters LTD
800-GO-SOLAR

-----Original Message-----
From: keith [mailto:kcronin at lava.net]
Sent: Monday, March 24, 2003 10:23 PM
To: RE-wrenches at topica.com
Subject: cellular pv site project [RE-wrenches]


Wrenches....

Has anyone done any pv generation work for any of our cellular carriers?
I got a call looking to do one.  I understand the 24 volt positive
ground from the 1930's.  The one I am not sure about is the standard
120/240 volt 200 amp service that most of these are powered by, via the
utility company.  I received a verbal 45 amp constant load as a
preliminary number to shoot for.  I thought most phone/cellular
equipment was dc in the first place? A 45 amp load is a giant pv load
for a 24/7/365 application. I think the load can be a lot smaller
without all of the inefficiencies with the ac-dc losses.

Any experienced wrenches would like to comment?

Keith Cronin
Island Energy Solutions
318 A Kuulei Road
Kailua, Hawaii 96734
808-262-3268 Tel
808-263-0338 Fax
www.islandenergy.net

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