Allan...indeed this is a limitation....and yes i agree with you that a higher voltage charge controller would be a welcome update to Outbacks line up.....Looking at the DPW top of pole list, i would suggest to you a design using 15 255 watt modules with the FM80 charge controller which would both meet your total wattage requirements, would still only need one charge controller, as well as conform to the 3 module multiplication requirement....additionally it would require less foundation/excavation work, but would in fact be a honker of an array....just an idea! Locally in your area I know Focused Energy has a good price and availability of the US made SolarWorld 255's which we use often...<div>
Good luck.</div><div>Kirpal<br><br><div class="gmail_quote">On Sun, Dec 16, 2012 at 10:41 AM, Allan Sindelar <span dir="ltr"><<a href="mailto:allan@positiveenergysolar.com" target="_blank">allan@positiveenergysolar.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
Wrenches,<br>
Please tell me if I'm overlooking something, in what appears to be a
design weakness:<br>
<br>
I would like to use an Outback Radian system for a standard GTBB
system. In order to take full advantage of the system's
capabilities, I have to use all of Outback's main components; in
this case the FM60 or FM80 charge controller. The problem is that
the most common (and lower-cost) modules today are 60-cell, meaning
20 Vnominal. Given the 150V DC hard maximum voltage limit of the
FM-series charge controller, in our cold climate I can only use
these 20V modules in 60 Vnominal series strings; that is, in
multiples of three modules. As the Radian is (wisely) offered in 48V
only, pairs of modules would provide too low a voltage, and series
strings of four modules would exceed 150 Voc in cold weather. <br>
<br>
The base Midnite Classic 150 will safely operate to 198 VDC in this
application, but it won't communicate with the Mate3.<br>
<br>
Is this a fundamental design limitation in the Radian system,
suggesting that Outback is due for a controller upgrade, or am I
missing something obvious? It appears that arrays and racks have to
be sized in ~720-watt sets of three-module series strings, which can
be problematic in some designs. In the design in question I would
like to use 16 240W modules on two 8-module pole-top racks (for
seasonal adjustability); nothing in sets of three meets the
customer's output and aesthetic needs. <br>
<br>
Any solutions would be welcome.<br>
Thank you,<br>
Allan<span class="HOEnZb"><font color="#888888"><br>
<div>-- <br>
<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com" target="_blank"><font face="Times New Roman, Times, serif" color="#000099"><u>Allan@positiveenergysolar.com</u></font></a></small><font face="Times New Roman, Times, serif"><br>
<span style="font-size:10pt">NABCEP Certified Photovoltaic
Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<br>
<b>Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<br>
<b><a href="tel:505%20424-1112" value="+15054241112" target="_blank">505 424-1112</a></b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank"><u>www.positiveenergysolar.com</u></a><u></u><u></u></span></font>
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