<div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif">Not to hijack the thread, but I'd like to add that the inverter rating required for enormous loads can also be beyond practical limits. We are getting a flood of grid-tie with PV and battery backup requests for whole house coverage. The reason for the consumer demand is obvious here in hurricane-prone SW Florida, especially this time of year. </div>
<div class="gmail_default" style="font-family:verdana,sans-serif"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif">The answer is usually to steer the customer into a critical load system, still with a sizable battery, and a very large PV array. Theoretically this could result in similar multiple discharge cycles per day if daytime loads are significant enough relative to the battery and the PV production is variable (think air conditioning).</div>
<div class="gmail_default" style="font-family:verdana,sans-serif"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif">I'll watch this discussion with interest...</div><br><br><div id="WISESTAMP_SIG_gmail_session">
<div style="font-size:13px;font-family:Verdana,Arial,Helvetica,sans-serif"><div style="margin:0 0 8px 0"><p style="margin:0"><span><span>Jason Szumlanski</span></span></p><p style="margin:0"></p><div class="gmail_default" style="font-family:verdana,sans-serif;display:inline">
Fafco Solar</div><br> <p></p><div style="clear:both"></div></div></div></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Aug 16, 2013 at 1:53 PM, William Miller <span dir="ltr"><<a href="mailto:william@millersolar.com" target="_blank">william@millersolar.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
<div>
<div><span><font size="4" face="Arial">Friends:</font></span></div>
<div><span><font size="4" face="Arial"></font></span> </div>
<div><span><font size="4" face="Arial">We have been
receiving a flurry of requests for design of off-grid systems where the loads
are enormous, relative to normal off-grid requirements. It is obvious that
the size of PV and battery arrays to power these loads is beyond what is
practical. We have dubbed these systems Generator/battery with PV assist,
or PV assist for short.</font></span></div>
<div><span><font size="4" face="Arial"></font></span> </div>
<div><span><font size="4" face="Arial">These systems will
cycle batteries multiple times per day. It is my understanding that the
extra battery cycels will shorten battery life. Since generator run is
expected, we are willing to increase generator run time in order to prolong
battery life.</font></span></div>
<div><span><font size="4" face="Arial"></font></span> </div>
<div><span><font size="4" face="Arial">The parameters I
suggest are an aggressive load start and a very high battery start
parameter. This will prevent deep discharge of the battery bank. I
know shallow discharge is not the norm, but I don't believe shallow cycling is a
problem as long is it as at the top of the voltage window, i.e. the batteries
achieve absorption at least once per day.</font></span></div>
<div><span><font size="4" face="Arial"></font></span> </div>
<div><span><font size="4" face="Arial">We know a load
start ciuld result in an abbreviated run time, curtailing absorption
period, but we are assuming there will be a battery votage start at least once
per day allowing full absorption.</font></span></div>
<div><span><font size="4" face="Arial"></font></span> </div>
<div><span><font size="4" face="Arial">Has anyone else
considered these issues, and what conclusions did you make</font></span></div>
<div><span><font size="4" face="Arial"></font></span> </div>
<div><span><font size="4" face="Arial">I am looking forward
to a spirited discussion as usual. I throuroughlyenjoy and beneift from
them, even thought the advice is usually conflilcting. Thanks in
advance.</font></span></div><span class="HOEnZb"><font color="#888888">
<div><span><font size="4" face="Arial"></font></span> </div>
<div><span><font size="4" face="Arial">William
Miller</font></span></div>
<div><span><font size="4" face="Arial"></font></span> </div></font></span></div>
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