[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: (ET) kill-a-watt

et jpjt net wrote:
 > Now my question is, why is the OK4U and its equivalent Trace MS100 no

longer available in the US?  Did the UL or utilities pressure it out of the
market?  Are there alternatives?


I'm not exactly sure. I think it had to do with the fact that the
anti-islanding specifications were changed around NEC 98 or NEC 2001.
Normally you have to have a disconnect between the DC source and the
input to the inverter to meet code; obviously you can't have a
disconnect on every panel.
Which is a screaming shame to be honest: The concept of having each solar panel equipped with it's own MPPT tracking controller would allow you to deploy an array in a mixed-shade configuration and still be ensured of max power possible from every panel.
If you want to do something like this nowadays you can spend $350+ for a used OK4U (they pop up on Ebay sometimes) or just get yourself a Sunny Boy 700 for $1,000 or so. Three OK4's would cost the SB, and the SB is a much more modern bit of technology.
Myself, I have two strings of 75 watt panels hooked up to a Sunny boy 1800 inverter. Works pretty well actually; I like it. 

Chris





Joel

Original Message:
-----------------
From: Tim Humphrey hump evgrin com
Date: Thu, 21 Dec 2006 7:33:55 -0700
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) kill-a-watt






Chris Wrote:


David Roden wrote:

On 20 Dec 2006 at 13:09, Christopher Zach wrote:


he's using a grid-tie inverter.

Yes, but unless I misunderstood the description, he's backfeeding the
Kill-a- watt meter.  Unless he modified the KaW, that would require a
double-male cable, no?  Or am I missing something here?



Typical use of the OK4U was to put a plug on it and plug it into the

nearest

wall. This would handle the NEC of the 90's, I think it was NEC
02 that called for a dedicated breaker for all grid tie thingies.



I know some folks will dismiss this concern, but IMO it's not a great
idea to even have such a cable around the house. There's too much
chance of an accident.  Even an adult can grab it, thinking it's an
extension cord, and get a nasty surprise.  For a little tyke, it could be

disfiguring or fatal.



Since it can't generate power without the grid (ie plugged in) and drops
power as soon as you unplug it it's about as safe as any appliance.



But Nellie's point was, the fact that a double ended cable exists lends
itself to disaster *ANYBODY* can take it and plug it into the a normal
outlet and end up with exposed live prongs.

I agree with David, I also agree with Chris. In Chris's scenario the cable
should be considered safe. BUT, remove the cable from that specific
environment and it now becomes very dangerous. There are, I do not know the
model number or name, cable ends that have a prong cover that moves away to
expose the prongs when inserted into an outlet. Those are the minimum I
would expect to see on such a cable (both ends). If anybody knows a source
for these I would appreciate it, I need some....

--
Stay Charged!
Hump
I-5, Blossvale NY




_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak


--------------------------------------------------------------------
mail2web - Check your email from the web at
http://mail2web.com/ .



_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak