<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">I agree with Allan and Bob-O that
overall this is not going to work so well. It will probably take
you a set of batteries that fail in 3 years instead of five to
come to this same conclusion as the guys that have been wrenching
for a long time. Its going to be a chronic, long term issue, not
an immediate "its going to fry" problem. The chance of success
improves in the following "Rosy" scenario: a higher voltage 60
cell module than the Kyocera, a small gel cell battery (lower
charge voltage) Warm battery (with temp compensation) Cold
module, cold climate, and virtually no load during absorption
charge.<br>
Then it might actually get normal battery life, but that's just
too many ifs for any of my off grid work.<br>
I'd go with 2 modules in series with MPPT, or drop to a 12 v
battery with MPPT. <br>
Solar Converters makes a controller that can mate low voltage
arrays to higher voltage batteries, but as our fine rep from BZ
Products noted: the efficiency isn't so good.<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
On 6/4/2013 3:17 PM, Allan Sindelar wrote:<br>
</div>
<blockquote cite="mid:51AE5981.5080500@positiveenergysolar.com"
type="cite">
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
<div class="moz-cite-prefix">Eric,<br>
Thanks for sticking with me on this. OK, that makes more sense.
You're not saying that it's an unregulated float, but only that
float will allow load to pass through as needed to maintain
float voltage, up to the limit of either the available array or
the controller's capacity, whichever is less. <br>
<br>
I still wonder whether a modest load on the charge during bulk
would likely prevent the controller from ever reaching the bulk
voltage, given that the module would be operating above its MPP
knee, and thus with greatly reduced current (depending on
temperature and other factors). If that occurred, would the
controller just stay in bulk mode indefinitely?<br>
Allan<br>
<br>
<div class="moz-signature">
<meta http-equiv="content-type" content="text/html;
charset=ISO-8859-1">
<title></title>
<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a moz-do-not-send="true"
href="mailto:Allan@positiveenergysolar.com"><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>505 424-1112</b><br>
<a moz-do-not-send="true"
href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font>
<p class="MsoNormal" style="margin-right: 722.25pt;"><span
style="font-size: 10pt;"><font face="Times New Roman,
Times, serif"><st1:place w:st="on"><st1:city w:st="on"></st1:city><st1:state
w:st="on"></st1:state><st1:postalcode w:st="on"></st1:postalcode></st1:place></font><b
style=""><br>
</b></span></p>
<span style="font-size: 10pt;"><br>
</span> </div>
On 6/4/2013 3:02 PM, <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:Eric.Bentsen@schneider-electric.com">Eric.Bentsen@schneider-electric.com</a>
wrote:<br>
</div>
<blockquote
cite="mid:OF0DC12FDE.7B5BBD37-ON88257B80.00701A77-88257B80.007330C5@US.Schneider-Electric.com"
type="cite"> <br>
<font face="sans-serif" size="2">Allen,</font> <br>
<font face="sans-serif" size="2">The C-series will provide 100%
duty cycle until the bulk voltage is reached. Assuming no
load, duty cycle will be reduced</font> <br>
<font face="sans-serif" size="2"> thru the absorption stage to
hold the battery at the bulk level (this occurs due to the
internal resistance of the battery increasing,</font> <br>
<font face="sans-serif" size="2"> requiring less and less
current to hold the battery at bulk). After 1 hour, the
C-series will reduce the duty cycle even more to allow </font>
<br>
<font face="sans-serif" size="2">the battery to drop to a float
level. Duty cycle will increase up to 100% while in float if
load demand if present. If load exceeds solar </font> <br>
<font face="sans-serif" size="2">watts, the voltage in the
battery will drop. Once.5V below bulk setting (24V system),
the C-series starts a new charge cycle. </font> <br>
<font face="sans-serif" size="2">We are assuming NOTC of 20C
(68F), so there will be some reduction of output at the bulk
level. Considering AGM and gel batteries</font> <br>
<font face="sans-serif" size="2"> would bulk around 28.2VDC,
efficiency losses should not be too extreme. Also, when using
battery temp sensor, the charger will</font> <br>
<font face="sans-serif" size="2"> target lower charge voltage as
temp increases.</font> <br>
<font face="sans-serif" size="2">Obviously the MPPT would be
optimal, with 2 or 3 modules in series.</font> <br>
<font face="sans-serif" size="2">Eric Bentsen<br>
</font><font size="3" color="#008000">_____________________________________________________________________________________</font><font
size="3"> <br>
</font><font face="Arial" size="1"><b><br>
Eric Bentsen</b> | </font><font face="Arial" size="1"
color="#008000"><b> Schneider Electric </b></font><font
face="Arial" size="1"><b> | Solar Business</b> | <b>UNITED
STATES</b> | <b>Technical Support Representative</b> <b><br>
Phone:</b> +(650) 351-8237 ext. 001# | <b><br>
Email:</b> </font><a moz-do-not-send="true"
href="mailto:eric.bentsen@schneider-electric.com"><font
face="Arial" size="1" color="blue"><u>eric.bentsen@schneider-electric.com</u></font></a><font
face="Arial" size="1"> | <b>Site:</b></font><a
moz-do-not-send="true"
href="http://www.schneider-electric.com/solar" target="_blank"><font
face="Arial" size="1" color="blue"><u>
www.schneider-electric.com/solar</u></font></a><font
face="Arial" size="1"> | <b>Address:</b> 250 South Vasco
Rd., Livermore, CA 94551 <br>
</font><font face="Arial" size="1" color="blue"><u><br>
</u></font><a moz-do-not-send="true"
href="www.schneider-electric.com/solar"><img
src="cid:part6.08080702.06090907@solarray.com"></a><font
face="Arial" size="1" color="#00a000"><br>
*** Please consider the environment before printing this
e-mail</font><font face="Arial" size="1"> </font><font
size="3"><br>
</font> <br>
<br>
<br>
<table width="100%">
<tbody>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">From:</font>
</td>
<td><font face="sans-serif" size="1">Allan Sindelar <a
moz-do-not-send="true" class="moz-txt-link-rfc2396E"
href="mailto:allan@positiveenergysolar.com"><allan@positiveenergysolar.com></a></font>
</td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">To:</font>
</td>
<td><font face="sans-serif" size="1"><a
moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:Eric.Bentsen@schneider-electric.com">Eric.Bentsen@schneider-electric.com</a></font>
</td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Date:</font>
</td>
<td><font face="sans-serif" size="1">06/04/2013 12:57 PM</font>
</td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Subject:</font>
</td>
<td><font face="sans-serif" size="1">Re: [RE-wrenches] 24V
charging with 60 cell modules</font></td>
</tr>
</tbody>
</table>
<br>
<hr noshade="noshade"> <br>
<br>
<br>
<font size="3">Eric,<br>
I understand what you write about PWM being able to do what
MPPT can't because of the buck function, but not the rest.
What I understand you're saying is that float mode on the
C-series controller is unregulated; that is, rather than hold
the battery to float voltage, it will pass module current
through until Voc is reached, or until the battery rises as
high as it is able given the available current. If so, that
goes against all I have observed, and even against the concept
of a regulated float voltage. <br>
<br>
David Katz wrote: "</font><font face="Verdana" size="3">You
can do it if you don’t need much power. That module will
float and equalize the battery but as the voltage rises, the
current will drop significantly. I used one 230 watt module
for a year to charge a 24 volt battery with an 11 watt load on
it and it worked fine. It is probably cheaper than buying two
50 watt 36 cell modules and putting them in series." </font><font
size="3">I accept that logic, although it breaks all the old
rules. A 230W 20V module is cheaper than two 50W 12V modules -
I get to explain that wackiness to customers on a regular
basis. But the kicker is the 11W load - even if continuous,
it's only 264 watt-hours/day, less than two hours' output of
the oversized module. My opinion is that if the load is much
larger than that, the bulk setpoint, which triggers the
one-hour absorption and transition to float, will never be
reached. <br>
<br>
Brian's excellent post really captures the principles involved
well. As battery voltage rises above Vmp, current drops
sharply. It'll work, sort of, but is poor design.<br>
<br>
Also, you wrote "</font><font face="sans-serif" size="2">The
question was making a single 24V module work with a 24V
battery.</font><font size="3">" I assume that you meant "</font><font
face="sans-serif" size="2">The
question was making a single 20V module work with a 24V
battery.</font><font size="3">", as that's the original issue,
and this was just a typo. If not, and you meant what you
wrote, we need to start over with this discussion... <br>
Thank you., <br>
Allan<br>
</font> <br>
<font face="Times New Roman" size="3"><b>Allan Sindelar</b></font><font
size="2" color="blue"><u><br>
</u></font><a moz-do-not-send="true"
href="mailto:Allan@positiveenergysolar.com"><font face="Times
New Roman" size="2" color="#0000a1"><u>Allan@positiveenergysolar.com</u></font></a><font
face="Times New Roman" size="2"><br>
NABCEP Certified Photovoltaic Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<b><br>
Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<b><br>
505 424-1112</b></font><font face="Times New Roman" size="2"
color="blue"><u><br>
</u></font><a moz-do-not-send="true"
href="http://www.positiveenergysolar.com/" target="_blank"><font
face="Times New Roman" size="2" color="blue"><u>www.positiveenergysolar.com</u></font></a><font
size="3"> </font>
<p> </p>
<p> <br>
<font size="3">On 6/4/2013 12:31 PM, </font><a
moz-do-not-send="true"
href="mailto:Eric.Bentsen@schneider-electric.com"><font
size="3" color="blue"><u>Eric.Bentsen@schneider-electric.com</u></font></a><font
size="3"> wrote:</font> <br>
<font face="sans-serif" size="2"><br>
Hi Allan,</font><font size="3"> <br>
</font><font face="sans-serif" size="2"><br>
The C-series behaves in the same way as if you were to
connect the module directly to the battery, <br>
then watch a DC volt meter and disconnect/reconnect when the
bulk voltage is reached to "hold" the battery <br>
at that level. It will hold at the bulk level for 1 hour,
then transition to float.</font><font size="3"> </font><font
face="sans-serif" size="2"><br>
If left connected without disconnecting, the voltage would
eventually climb to Voc (approx 36VDC). So, while it is not
<br>
going to be as efficient as the MPPT controller in the
bulk/absorption stages, once the PWM controller transitions
to float, <br>
it will operate right about the sweet spot (Vmp). The
question was making a single 24V module work with a 24V
battery.</font><font size="3"> </font><font
face="sans-serif" size="2"><br>
PWM is the only way to do it, as the MPPT requires a higher
PV voltage due to the use of a buck transformer.</font><font
size="3"> </font><font face="sans-serif" size="2"><br>
I will certainly pass on any recommendations for improvement
to our engineering team, and <br>
I appreciate the feedback.</font><font size="3"> <br>
</font><font face="sans-serif" size="2"><br>
Eric Bentsen</font><font size="3"> </font><font
face="sans-serif" size="2"><br>
</font><font size="3" color="#008000"><br>
_____________________________________________________________________________________</font><font
size="3"> </font><font face="Arial" size="1"><b><br>
<br>
Eric Bentsen</b> | </font><font face="Arial" size="1"
color="#008000"><b> Schneider Electric </b></font><font
face="Arial" size="1"><b> | Solar Business</b> | <b>UNITED
STATES</b> | <b>Technical Support Representative</b> <b><br>
Phone:</b> +(650) 351-8237 ext. 001# | <b><br>
Email:</b> </font><a moz-do-not-send="true"
href="mailto:eric.bentsen@schneider-electric.com"><font
face="Arial" size="1" color="blue"><u>eric.bentsen@schneider-electric.com</u></font></a><font
face="Arial" size="1"> | <b>Site:</b></font><a
moz-do-not-send="true"
href="http://www.schneider-electric.com/solar"
target="_blank"><font face="Arial" size="1" color="blue"><u>
www.schneider-electric.com/solar</u></font></a><font
face="Arial" size="1"> | <b>Address:</b> 250 South Vasco
Rd., Livermore, CA 94551 </font><font face="Arial" size="1"
color="blue"><u><br>
</u></font><font size="3" color="blue"><u><br>
</u></font><a moz-do-not-send="true"
href="www.schneider-electric.com/solar"><img
src="cid:part15.02010809.08040207@solarray.com"></a><font
face="Arial" size="1" color="#00a000"><br>
*** Please consider the environment before printing this
e-mail</font><font face="Arial" size="1"> </font><font
size="3"><br>
<br>
<br>
</font>
<table width="100%">
<tbody>
<tr valign="top">
<td width="14%"><font face="sans-serif" size="1"
color="#5f5f5f">From:</font><font size="3"> </font>
</td>
<td width="85%"><font face="sans-serif" size="1">Allan
Sindelar </font><a moz-do-not-send="true"
href="mailto:allan@positiveenergysolar.com"><font
face="sans-serif" size="1" color="blue"><u><allan@positiveenergysolar.com></u></font></a><font
size="3"> </font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">To:</font><font
size="3"> </font> </td>
<td><font face="sans-serif" size="1">RE-wrenches </font><a
moz-do-not-send="true"
href="mailto:re-wrenches@lists.re-wrenches.org"><font
face="sans-serif" size="1" color="blue"><u><re-wrenches@lists.re-wrenches.org></u></font></a><font
size="3"> </font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Date:</font><font
size="3"> </font> </td>
<td><font face="sans-serif" size="1">06/04/2013 10:35 AM</font><font
size="3"> </font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Subject:</font><font
size="3"> </font> </td>
<td><font face="sans-serif" size="1">Re: [RE-wrenches]
24V charging with 60 cell modules</font><font
size="3"> </font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Sent
by:</font><font size="3"> </font> </td>
<td><a moz-do-not-send="true"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org"><font
face="sans-serif" size="1" color="blue"><u>re-wrenches-bounces@lists.re-wrenches.org</u></font></a></td>
</tr>
</tbody>
</table>
<br>
<font size="3"><br>
</font> </p>
<hr noshade="noshade"><font size="3"><br>
<br>
<br>
Eric,<br>
Please explain further, as what you wrote makes no sense to
me. Mac didn't indicate whether he wanted to charge a flooded
battery (~29.2V) or sealed (~28.4V). The C-series of PWM
controllers has a fixed two-hour absorption, which it only
counts down once the bulk voltage is reached. If the bulk
voltage setpoint is above the MPP of the module, as it is in
this case, how can it ever reach float, as you suggest?<br>
<br>
And further, this is spec-sheet calculation. In all but the
coldest winter weather, the Vmp of the module will be lower
still as the module temperature rises above 25ºC, and is
likely to be even below the float voltage in hot weather. And
in the winter, if the battery is also cold, it will need a
higher voltage still to get fully charged.<br>
<br>
So I'm with Bob-O on this one. You can't charge a 24V battery
with a 20V module. Please tell us how I'm wrong.<br>
Thanks, Allan<br>
<br>
P.S. - And while I'm on a virtual roll, please tell your
engineering folks to build a charge controller with a higher
voltage input window. I don't mean 600 volts at $1,500 or
whatever it is; just higher than 150V. On a 48V system, we're
stuck with series strings of three modules if we use the
lowest-cost-per-watt 60-cell modules. That means that systems
have to be designed with arrays in ~750-watt increments. Give
us another 50-100V or so of headroom, so we can design with
strings in multiples of 3, 4, or 5. Outback, are you listening
too? The Midnite Classic does this for us... Thanks.<br>
</font><font face="Times New Roman" size="3"><b><br>
Allan Sindelar</b></font><font size="3" color="blue"><u><br>
</u></font><a moz-do-not-send="true"
href="mailto:Allan@positiveenergysolar.com"><font face="Times
New Roman" size="2" color="#0000a1"><u>Allan@positiveenergysolar.com</u></font></a><font
face="Times New Roman" size="2"><br>
NABCEP Certified Photovoltaic Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<b><br>
Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<b><br>
505 424-1112</b></font><font size="3" color="blue"><u><br>
</u></font><a moz-do-not-send="true"
href="http://www.positiveenergysolar.com/" target="_blank"><font
face="Times New Roman" size="2" color="blue"><u>www.positiveenergysolar.com</u></font></a><font
size="3"> </font>
<p><font size="3"><br>
On 6/4/2013 10:43 AM, </font><a moz-do-not-send="true"
href="mailto:Eric.Bentsen@schneider-electric.com"><font
size="3" color="blue"><u>Eric.Bentsen@schneider-electric.com</u></font></a><font
size="3"> wrote: </font><font face="sans-serif" size="2"><br>
<br>
Hi Mac,</font><font size="3"> </font><font
face="sans-serif" size="2"><br>
<br>
A PWM charge controller, such as the C35, will work in this
application, because it will <br>
act like a switch that connects the panel to the battery.
While the bulk voltage will likely be slightly</font><font
size="3"> </font><font face="sans-serif" size="2"><br>
higher than Vmp, once the controller transitions to float,
which is approx 27V for most battery types,</font><font
size="3"> </font><font face="sans-serif" size="2"><br>
it should allow the module to operate very close to Vmp. <br>
Typically, MPPT controllers require a higher Vmp than the
target charge voltage.</font><font size="3"> </font><font
face="sans-serif" size="2"><br>
<br>
Eric Bentsen</font><font size="3" color="#008000"><br>
_____________________________________________________________________________________</font><font
size="3"> </font><font face="Arial" size="1"><b><br>
<br>
Eric Bentsen</b> | </font><font face="Arial" size="1"
color="#008000"><b> Schneider Electric </b></font><font
face="Arial" size="1"><b> | Solar Business</b> | <b>UNITED
STATES</b> | <b>Technical Support Representative</b> <b><br>
Phone:</b> +(650) 351-8237 ext. 001# | <b><br>
Email:</b> </font><a moz-do-not-send="true"
href="mailto:eric.bentsen@schneider-electric.com"><font
face="Arial" size="1" color="blue"><u>eric.bentsen@schneider-electric.com</u></font></a><font
face="Arial" size="1"> | <b>Site:</b></font><a
moz-do-not-send="true"
href="http://www.schneider-electric.com/solar"
target="_blank"><font face="Arial" size="1" color="blue"><u>
www.schneider-electric.com/solar</u></font></a><font
face="Arial" size="1"> | <b>Address:</b> 250 South Vasco
Rd., Livermore, CA 94551 </font><font size="3" color="blue"><u><br>
<br>
</u></font><a moz-do-not-send="true"
href="www.schneider-electric.com/solar"><img
src="cid:part25.08020406.00080400@solarray.com"></a><font
face="Arial" size="1" color="#00a000"><br>
*** Please consider the environment before printing this
e-mail</font><font face="Arial" size="1"> </font><font
size="3"><br>
<br>
</font>
<table width="100%">
<tbody>
<tr valign="top">
<td width="15%"><font face="sans-serif" size="1"
color="#5f5f5f">From:</font><font size="3"> </font>
</td>
<td width="84%"><font face="sans-serif" size="1">Mac
Lewis </font><a moz-do-not-send="true"
href="mailto:maclewis1@gmail.com"><font
face="sans-serif" size="1" color="blue"><u><maclewis1@gmail.com></u></font></a><font
size="3"> </font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">To:</font><font
size="3"> </font> </td>
<td><font face="sans-serif" size="1">RE-wrenches </font><a
moz-do-not-send="true"
href="mailto:re-wrenches@lists.re-wrenches.org"><font
face="sans-serif" size="1" color="blue"><u><re-wrenches@lists.re-wrenches.org></u></font></a><font
size="3"> </font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Date:</font><font
size="3"> </font> </td>
<td><font face="sans-serif" size="1">06/04/2013 08:05 AM</font><font
size="3"> </font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Subject:</font><font
size="3"> </font> </td>
<td><font face="sans-serif" size="1">[RE-wrenches] 24V
charging with 60 cell modules</font><font size="3">
</font> </td>
</tr>
<tr valign="top">
<td><font face="sans-serif" size="1" color="#5f5f5f">Sent
by:</font><font size="3"> </font> </td>
<td><a moz-do-not-send="true"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org"><font
face="sans-serif" size="1" color="blue"><u>re-wrenches-bounces@lists.re-wrenches.org</u></font></a></td>
</tr>
</tbody>
</table>
<br>
<font size="3"><br>
</font> </p>
<p> </p>
<hr noshade="noshade"><font size="3"><br>
<br>
<br>
Hello wrenches, <br>
<br>
Is there a good method to charge 24V battery bank with single
60 cell modules? Ideally, I'd like to charge a 24 V bank with
a Kyocera 245GX-LFB. However, at NOTC the Vmp is 26.8V. Any
good way to do this? <br>
<br>
Thanks in advance.<br>
-- <br>
<br>
<br>
<br>
Mac Lewis </font>
<p><font size="2" color="#37605e">"Yo solo sé que no sé nada." </font><font
size="2" color="#5f5f5f">-Sócrates</font><font size="3"> </font>
</p>
<br>
</blockquote>
</blockquote>
<br>
</body>
</html>