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<div class="moz-cite-prefix">Hilton,<br>
That sounds like a good idea at first glance but a bad one when
you dig a bit deeper. In essence he is sacrificing proper
absorption on the batteries and will pay the price in reduced
battery capacity and life. As soon as the batteries reach the bulk
voltage setpoint, which is typically about 85% SOC and would
normally trigger the absorption stage, the charge current is
diverted to the heating element. As soon as the controller
switches it over, the battery voltage drops to the reconnect point
- sort of like an old Trace C30A, which was never a good
controller. In the best case, the energy cycles back and forth
between absorption and diversion, or if the controller has PWM, I
suppose a portion would go to each.<br>
<br>
Somehow I just can't see how it could be made to work without
these inherent complications.<br>
Allan<br>
<br>
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<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a 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 href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font>
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style=""><br>
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On 5/14/2013 6:22 PM, Hilton Dier III wrote:<br>
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<blockquote cite="mid:5192D559.5010409@gmail.com" type="cite">
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<font face="Times New Roman, Times, serif">A friend of mine lives
off grid with PV and wind. He added a shunt-type controller to
his battery bank and connected it to a DC heating element in his
hot water tank. Below a set voltage the </font>element is
dormant. When the battery bank hits a high voltage (at the end of
a particularly sunny day or during a windy spell) the element
comes on. That way, instead of just a PWM shutoff and wasted
energy, he gets some benefit.<br>
<br>
I wouldn't deliberately install PV just for hot water, but in an
off grid situation where the excess would go to waste, it makes
sense.<br>
<br>
Hilton<br>
<pre class="moz-signature" cols="72">--
Hilton Dier III
Renewable Energy Design
Partner, Solar Gain LLC
453 East Hill Rd.
Middlesex, VT 05602</pre>
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