ratcheting cyclometers [RE-wrenches]

[Jeffery Wolfe, Global Resource Options]

Kelly,

In order to capture all of the RE power, you need to also measure the AC
Load output to the battery backed up sub panel. This can be a substantial
portion of the total power generated.

WE've just started using Davidge Controls electronic meters. They make a
variety of devices, including one that measures power in each direction on a
bi-directional line. I believe it's called the "Everglades" model. You would
need this, plus a "Sequoia" model for the unidirectional power to the sub
panel.

They are easy to install, although we've had two problems in our first
application: wrong transducer sent, and then a bad unit. So my jury is out
still as to whether we'll continue to use it, but it's the cheapest method
I've been able to figure out so far for actually measuring real PV power
generation on an SW type installation. Total equipment cost is in the range
of $300. Each meter has it's own mechanical "odometer" type readout (two for
the Everglades). There is also an upgrade for computer input.

The problems with ratchet meters that I've seen is that although they only
measure the power in one direction, they will let it flow in either
direction. Thus, you cannot simply install two opposing ratchet meters to
measure the power on a bi-directional line. Am I wrong? (It would be cheaper
if I was wrong!)

Jeff Wolfe
Global Resource Options

-----Original Message-----
From: Kelly Keilwitz [mailto:kelly at whidbeysunwind.com]
Sent: Tuesday, December 02, 2003 5:09 PM
To: RE Wrenches listserve
Subject: ratcheting cyclometers [RE-wrenches]


Hi all,

We have several battery-based grid-tied solar and wind systems where the
owners are selling the "green attributes" of their production, aside from
net-metering with the utility. In order to track total production a seperate
utility-style meter is required. Because these are battery-based systems a
ratcheting meter is preferred (so that grid-power used to charge the
batteries is not subtracted from the RE production). Cyclometers (odometer
style dials) are easier to read than those goofey hands that rotate in
opposite directions.

Ideally I would like to find 120volt, ratcheting, cyclometer utility style
meters. Anyone know where I can find such animals?

Thanks
-Kelly


Kelly Keilwitz, P.E.
Whidbey Sun & Wind
Renewable Energy Systems
986 Wanamaker Rd, Coupeville, WA 98239
ph & fax: 360-678-7131
sunwind at whidbeysunwind.com
www.whidbeysunwind.com
Renewable Energy Now!

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