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I have learned from experience that small inverter-generators can have
problems in this application, depending on the inverter. For instance,
with an Outback inverter, you need to size the gennie large enough to
handle loads and surges larger than the programmed battery charging
rate, as the Outback lacks the full inverter support we had with the SW
series. Other inverters have this same issue. The inverter isn't fast
enough to control a surge load and can trip the gennie's output
breaker. <br>
<br>
We have seen that the 3000W Yamaha inverter-generator will lug when
overloaded before tripping its breaker, but the Honda has a very
sensitive breaker that will trip on even a slight overload. The
tripping often goes unnoticed if the engine noise isn't audible in the
house.<br>
<br>
The problem is exacerbated by the need to charge the batteries at the
highest rate available from the generator/inverter combination, both
for decent C/rate and to minimize runtime. So setting the inverter
charge amps way back in order to leave some surge headroom defeats
these objectives. All of this is exacerbated when the generator is
small.<br>
<br>
We install at 6-8K' elevation, so we need to derate 25% +/- anyway. But
in one system the customer had a 3000W Honda inverter-generator, and we
installed a VFX3524 inverter, which maxes out at 19A AC charging input.
After numerous nuisance trips, we told the customer to leave everything
off while AC charging, plus pay attention to the charge rate to notice
if the output breaker trips.<br>
<br>
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<p class="MsoNormal" style=""><span class="il"><b style="">Allan</b></span><b
style=""> Sindelar</b><span style="font-size: 10pt;"><br>
<a href="mailto:Allan@positiveenergysolar.com" target="_blank"><span
class="il">Allan</span>@positiveenergysolar.com</a><br>
NABCEP Certified Photovoltaic Installer<br>
EE98J Journeyman Electrician<br>
<b style="">Positive Energy, Inc.</b><br>
3201 Calle Marie<br>
Santa Fe, New Mexico 87507<br>
<b style="">505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank">www.positiveenergysolar.com</a></span></p>
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<br>
<br>
Darryl Thayer wrote:
<blockquote cite="mid:832766.33888.qm@web51901.mail.re2.yahoo.com"
type="cite">
<pre wrap="">The system is way short on PV, and I would think that it is already a Gen with PV support. I agree with everybody more PV is the way to go but the batteries must be cooked by now with this many Deep cycles. BTW C/10 is not important, in fact I feel better if I charge slower. I know fast charging is a good way to kill batteries. Operating cost needs a high efficiency engine. So until you can get the PV up to become the dominant source, a gen is probibly in order. I tend to use smaller generators than most people, and the fuel efficency of a Honda inverter gen is hard to beat.
--- On Thu, 12/3/09, <a class="moz-txt-link-abbreviated" href="mailto:Windsun@wind-sun.com">Windsun@wind-sun.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:windsun@wind-sun.com"><windsun@wind-sun.com></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">From: <a class="moz-txt-link-abbreviated" href="mailto:Windsun@wind-sun.com">Windsun@wind-sun.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:windsun@wind-sun.com"><windsun@wind-sun.com></a>
Subject: Re: [RE-wrenches] Off-Grid Sizing Case
To: "RE-wrenches" <a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a>
Date: Thursday, December 3, 2009, 12:18 PM
Off-Grid Sizing Case
The rate of charging is not the
real problem in most
undersized systems, it is the fact that the batteries
seldom, if ever, get fully
charged. Given the ratio of PV vs battery capacity, I would
suspect that their
batteries have been chronically undercharged for ages. We
usually recommend
around 1 watt of pv per AH for a 12 volt system, 2
watts for 24 volt
etc.
A generator is not usually the
answer, because it may
have to run for hours to get that final 5-15% of charge
into the batteries.
Generators are good for equalizing, not so much for general
charging.
..................................................................................................
Northern
Arizona Wind & Sun - Electricity From The Sun Since
1979
Solar Discussion
Forum: <a class="moz-txt-link-freetext" href="http://www.wind-sun.com/ForumVB/">http://www.wind-sun.com/ForumVB/</a>
..................................................................................................
----- Original Message
-----
From:
Mark
Frye
To: 'RE-wrenches'
Sent: Thursday,
December 03, 2009 10:56
AM
Subject: Re:
[RE-wrenches] Off-Grid
Sizing Case
So being able to achieve C10
charging from the PV is not so
important?
Mark
Frye
Berkeley Solar
Electric
Systems
303 Redbud
Way
Nevada
City, CA 95959
(530) 401-8024
<a class="moz-txt-link-abbreviated" href="http://www.berkeleysolar.com">www.berkeleysolar.com</a>
From: <a class="moz-txt-link-abbreviated" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a class="moz-txt-link-freetext" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] On
Behalf Of <a class="moz-txt-link-abbreviated" href="mailto:Windsun@wind-sun.com">Windsun@wind-sun.com</a>
Sent:
Thursday, December 03, 2009 9:51 AM
To:
RE-wrenches
Subject: Re: [RE-wrenches] Off-Grid Sizing
Case
I would go with #1.
The solar is obviously
undersized for the battery bank he has. Another panel +
MPPT should give him
about 25-40% more, depending on temps etc.
</pre>
</blockquote>
</blockquote>
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