Hello Bill,
Henk Oldenkamp is the inventor of the OK4U microinverter. Perhaps David Katz
knows what Henk is up to lately. The OK4U inverter that I first tested on
the Solec International factory roof in 1994 worked ok (as specified).
The central inverters vs. multiple small inverters side-by-side comparison
was also in Los Angeles on a 400 kW PV array between 2 each Xantrex 100 kW
central inverters and 74 each SMA 2500 inverters (both circa 2003). The kW
and kWh output was the same for both configurations.
Joel Davidson
----- Original Message -----
From: "Bill Loesch" <solar1onl...@charter.net>
To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org>
Sent: Monday, May 09, 2011 7:10 AM
Subject: Re: [RE-wrenches] Side-by-side microinverter, maximizer,and
conventional inverter comparisons
Joel,
As I remember Trace rebranded the (nominal 100 watt) OK4U units as
MicroSine
about 2000 AD. Didn't SMA (or someone else) recently take over the OK4U
product line?
Do I understand you were not impressed with the MPPT OK4U microinverters
performance (vs. the non-MPPT SMA?) under full sun?
Do I understand correctly that you compared some 2,000 (OK4U?)
microinverter
units
with 74 transformerless (?) SMA machines?
The "as much as", "up to", etc. wording is why "caveat emptor" and "Your
Mileage May Vary" should accompany each one of those comments. Kudos
marketing mavens.
Bill Loesch
Solar 1 - Saint Louis Solar
314 631 1094
----- Original Message -----
From: "Joel Davidson" <joel.david...@sbcglobal.net>
To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org>
Sent: Wednesday, May 04, 2011 8:54 AM
Subject: [RE-wrenches] Side-by-side microinverter, maximizer,and
conventional inverter comparisons
Wrenches,
A few years ago, we compared conventional and MPPT charge controllers and
found power production improvement in only in unique conditions and
rarely
over 15%. Now Microinverter and DC maximizer companies are claiming "as
much
as 25%" increased electricity production and a booming market. See
http://www.interpv.net/market/market_view.asp?idx=401&code=401&part_code=01
I've been comparing grid-connected microinverters since 1994 when Henk
came
out with his OK4U and am not impressed in full-sun (no shade)
comparisons.
In 2005, I compared a side-by-side 200 kW system with two 100 kW Xantrex
inverters with a 200 kW system with 74 SMA inverters and saw no
difference
in kW or kWh.
Have any wrenches made side-by-side comparisons? Are the claimed
improvements hype or real?
Joel Davidson
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