Inverter Shoot-Out continues [RE-wrenches]

Joel Davidson joeldavidson at earthlink.net
Wed Mar 31 11:20:34 PST 2004


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Is anyone getting different SW dc-to-ac net metered conversion efficiency?

Original Message:
-----------------
From: Kirk Herander kirk at vtsolar.com
Date: Wed, 31 Mar 2004 12:05:49 -0500
To: RE-wrenches at topica.com
Subject: Re: Inverter Shoot-Out continues [RE-wrenches]

Joel,

Your 84%  dc/ac efficiency is exactly what I recorded with a SW net-metered
system.

Kirk
Vermont Solar Engineering
Kirk Herander
North American Board of Certified Energy Practitioners
Certified Solar PV Installer(TM)
Xantrex Certified Dealer Charter Member
NYSERDA-eligible installer
Vermont Solar and Wind Partner

PO Box 697
Burlington, VT. 05402
www.vermontsolar.com
www.backeastsolar.com
800.286.1252 - 802.863.1202
fax 802.863.7908

----- Original Message -----
From: "Joel Davidson" <joeldavidson at earthlink.net>
To: <RE-wrenches at topica.com>
Sent: Tuesday, March 30, 2004 8:30 PM
Subject: Re: Inverter Shoot-Out continues [RE-wrenches]


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**** Bounces like rubber! Shatters like ceramic! ****
Discover Crazy Aaron's Thinking Putty in grown up
handfuls. It's the creativity unleashing, mood enhancing
desk toy!
http://click.topica.com/caab5n2bz8Qcsa84x0Ea/ Crazy Aaron Enterprises
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Hello Antony,

I replaced my Trace C40 charge controller with an Outback MX60. I collect
data once a month when the electric utility bill arrives so it will be 3 or
4 months before I have enough comparative data. It's nice to be able to see
MX60 DC kWh and Brand Meter AC kWh.

March 28 was 9.7 DC kWh and 8.2 AC kWh
March 29 was 10.0 DC kWh and 8.4 AC kWh
Both days were sunny (950 W/m2 at POA at noon) and warm for the LAX area in
March (highs of 85F and 90F).

Best regards,
Joel Davidson

----- Original Message -----
From: "Antony Tersol" <tony at appliedsolarenergy.com>
To: <RE-wrenches at topica.com>
Sent: Tuesday, March 30, 2004 9:01 AM
Subject: RE: Inverter Shoot-Out continues [RE-wrenches]

As a wrenching organization, our focus is also overall system value, but
from a slightly different perspective than the CEC's.

In order to determine the value of a system, among my concerns are:

1. Properly configuring potential systems.  This requires knowing the
characteristics of both the modules and the inverters, and understanding the
interplay between those characteristics and the range of conditions expected
at the installation site (daily and yearly insolation, temperature, wind,
sun position, ...), OR relying on others (distributors, manufacturers, other
wrenches) for pre-configured systems that are properly engineered for the
locations of my customers.

2. Predicting the real-world performance so that I can estimate the economic
value and set realistic expectations for my customers.  In addition to
system performance characteristics, this requires knowing the local
conditions (weather, shading, ...) and having some method of simulation.
The model can only be verified by comparison with actual real-world
performance.

3. The reliability of components, and the customer service of the
manufacturers.  Here I must also be concerned with the business model and
ethics of the manufacturer.  Will they still be around through the life of
the system (or at least the life of the warranty)?  How responsive are they
when there is a problem?  What is the MTBF of their products?  Do they
readily provide the numbers that characterize their product?  (module
makers - where are your temperature coefficients?)

For these reasons, we need both the real world performance data of complete
systems AND laboratory testing of equipment to isolate the variables so that
the individual components are characterized.  Good testing protocols and
reasonable quality control by the manufacturer would lead to meaningful
results with the testing of a few units of each model (the Swiss module
testing facility randomly chooses from distributor's stock to prevent
manufacturer's "cherry-picking" the test subjects - http://leee.supsi.ch/
Look at LEEE-Tiso).

Because of the variability of the real world, real world performance data
needs to be available from large numbers of systems.  This would allow us to
refine our predictions and simulations, akin to translating auto sticker MPG
into our  own driving experience.  The real world data will only be
meaningful if we understand the causes of the variability.  Where will this
data come from?  Back in January I offered to collect this data from the
wrenches.  Only Joel responded.  Is he the only one who has collected data,
or is there no interest in real world performance?

We also need performance data about the manufacturers themselves.  This is
where this list contributes, both in allowing us to see firsthand the
responsiveness of the companies, and through the sharing of wrenches'
experience with customer service.

Antony

===========================================================
**** Bounces like rubber! Shatters like ceramic! ****
Discover Crazy Aaron's Thinking Putty in grown up
handfuls. It's the creativity unleashing, mood enhancing
desk toy!
http://click.topica.com/caab4CEbz8Qcsa84x0Ef/ Crazy Aaron Enterprises
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===========================================================
**** Bounces like rubber! Shatters like ceramic! ****
Discover Crazy Aaron's Thinking Putty in grown up 
handfuls. It's the creativity unleashing, mood enhancing 
desk toy!
http://click.topica.com/caab4CEbz8Qcsbc0WJAf/ Crazy Aaron Enterprises
===========================================================

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To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

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