<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Very good numbers. I've found their monthly "enlightener" that they send with each bill on line and found this interesting tidbit. </div><div><br></div><div>" if considering a PV system, know that not all contractors are the same. We are installing a model PV system at our main office so our customers can come to us with questions about PV systems a costs." </div><div><br></div><div>They are very "pro-coal", and I think I'm getting used. This system will be nothing like a system a residential customer would have installed and will cost significantly more that a GDI system. Do you think they will mention this to their co-op members that inquire about PV?</div><div><br></div><div>Jesse<br><br>Sent from my iPhone</div><div><br>On Jun 25, 2013, at 12:27 PM, "SunHarvest" <<a href="mailto:eric@harvesthesun.com">eric@harvesthesun.com</a>> wrote:<br><br></div><blockquote type="cite"><div>
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<div><font size="2" face="Arial">Hi Jesse,</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">If I read this correctly your customer is wanting
to go off-grid during peak hours. I recently went through this same thing with a
customer. I received feedback from an old SMA tech and some Wrenchers (thread
titled "Battery Back-up and Grid Tie"). Here's what I learned:</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">1. Inverters are more efficient at inverting than
charging, anywhere from 5-10%. Add to that about 10% transmission loss...you'll
always have significant energy losses associated with trying to put back that
power that you're drawing out during those peak hours. Energy loss = $$
loss.</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">2. Compare the utility peak kWh
cost against the cost of cycling the battery bank. Just for
an example, let's say for a 48V system you're using 150Ah 12V
Trojan AGMs $2000 for 8 batteries. If the specs say those batteries,
at 50% discharge, get 1000 cycles in their lifetime, that's $2.00 per
cycle. 300Ah X 48V X 50% = 7.2kWh. $2/7.2kWh = $0.28/kWh. Add to that 20%
round-trip efficiency losses, you're up to $0.33/kWh. What else
does daily, unnecessary cycling add: Extra maintenance? Shortened life so
probably should factor in some replacement cost?...</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">3. Murphy's law says that the power will go out at
the end of one of these non-essential discharge cycles. Then what?</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">Probably not worth it.</font></div>
<div><font size="2" face="Arial"></font> </div>
<div>Eric Stikes</div>
<div>SunHarvest</div>
<div>530-798-3738</div>
<blockquote style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<div style="FONT: 10pt arial">----- Original Message ----- </div>
<div style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><b>From:</b>
<a title="dahlsolar@gmail.com" href="mailto:dahlsolar@gmail.com">Jesse Dahl</a>
</div>
<div style="FONT: 10pt arial"><b>To:</b> <a title="RE-wrenches@lists.re-wrenches.org" href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches</a> </div>
<div style="FONT: 10pt arial"><b>Sent:</b> Monday, June 24, 2013 8:50 PM</div>
<div style="FONT: 10pt arial"><b>Subject:</b> [RE-wrenches] Battery bank
during peak times</div>
<div><br></div>
<div dir="ltr">Hello,
<div><br></div>
<div>I was contacted by a local co-op about installing a PV system at their
office. At first they wanted a straight grid-tied system, and after
they received the bid they changed their minds and now
want a battery based system price. What they want now is a system that will
allow them to draw the battery bank down starting at 5pm during
their peak demand time. Has anyone worked on or installed a system of this
type?</div>
<div><br></div>
<div><br></div>
<div>Thanks as always!</div>
<div><br></div>
<div><br></div>
<div>Jesse</div></div>
<p>
</p><hr>
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