<div dir="ltr">I'm not sure that AC coupling would work with the old SW inverters. Assuming they are stacked for 240V, I don't see why it couldn't work. I would actually like to know because I have dual SW5548's on my farm in the Caribbean and I am considering adding more PV. Adding PV on the DC side would be a bit difficult in this case. Since most of the load there is during the day, I would rather avoid the losses through the batteries and just add PV on the AC side of the off-grid inverter.<div>
<br></div><div>I was making more of a general statement. AC coupling would offset the impact from reducing the DC PV rating if you lose modules and have to reconfigure strings. It might not be the cheapest solution, but it might make the best long-term sense. Every situation is going to be different...<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 style="color:#808080"><strong>Jason Szumlanski</strong></span></p>
<p style="margin:0"><span style="color:#808080"><em>Fafco Solar</em></span><br></p></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jan 24, 2013 at 3:49 PM, Allan Sindelar <span dir="ltr"><<a href="mailto:allan@positiveenergysolar.com" target="_blank">allan@positiveenergysolar.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Jason,<br>
How do you AC couple some microinverters to cover the decrease in
performance in an off grid system, especially with older
equipment, such as an SW4024?<br>
Thanks, Allan<div class="im"><br>
<br>
<div>
<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com" target="_blank"><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><a href="tel:505%20424-1112" value="+15054241112" target="_blank">505 424-1112</a></b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank"><u>www.positiveenergysolar.com</u></a><u></u><u></u></span></font>
<p class="MsoNormal" style="margin-right:722.25pt"><span style="font-size:10pt"><font face="Times New Roman, Times,
serif"><u></u><u></u><u></u><u></u><u></u><u></u><u></u><u></u></font><b><br>
</b></span></p>
<span style="font-size:10pt"><br>
</span> </div></div><div><div class="h5">
On 1/24/2013 1:38 PM, Jason Szumlanski wrote:<br>
</div></div></div>
<blockquote type="cite"><div><div class="h5">
<div dir="ltr">I totally agree - old mods are usually not worth
messing with at today's PV prices. In some cases it might be
best to downsize the system and then AC couple some
microinverters to cover the decrease in performance, or just
replace the entire array if there are enough problems. There is
a used market for smaller PV mods on Craigslist.
<div>
<br>
</div>
<div>Back when I was installing Astropower 110W modules on
single voltage Xantrex C40's, I never thought we'd be using
anything but 12V nominal PV mods. Little did I know...
Off-grid is really tough in these retrofit situations, but
this applies to failed/broken mods on grid-tie systems as
well. That's where I can make a good case for microinverters.
<div>
<br>
<div>
<div style="font-size:13px;font-family:Verdana,Arial,Helvetica,sans-serif">
<div style="margin:0 0 8px 0">
<p style="margin:0"><span style="color:#808080"><strong>Jason
Szumlanski</strong><em> </em></span></p>
<p style="margin:0"><span style="color:#808080"><em>
Fafco Solar<br>
</em></span><br>
</p>
</div>
</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Thu, Jan 24, 2013 at 3:11 PM,
Ray Walters <span dir="ltr"><<a href="mailto:ray@solarray.com" target="_blank">ray@solarray.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Hi Allan;<br>
<br>
I've been in the same conundrum lately. I found
that AEE and others have 12 v modules (Solartech),
but the price per watt is double or triple. My
take is that somewhere around 200 to 400 watts,
its more cost effective to go to the GT modules
with an MPPT controller. Blue Sky makes the 1524,
and 3024 that can take up to 57 Voc, so those
would work at still fairly low cost.
Unfortunately many of the other low cost MPPT
controllers won't work with the 60 cell modules.
At some point, it may actually be cost effective
to just use 60 cell modules with non MPPT
controllers, and just forget about the extra 24
cells. (I know that sounds crazy, but PV less
than $1/ watt is crazy too)<br>
<br>
I'm trying to add modules to an existing array of
8 Siemens 12 v modules, and it just doesn't work
out, except with separate controllers. <br>
Also, its amazing how much PV you can throw at an
off grid project these days for $10k.<br>
It almost makes messing around with the old
modules a waste of time.<br>
Perhaps the solution might be to remove old arrays
for customers wanting to really up size, and then
reuse the old modules for small systems?<br>
<br>
Ray
<div>
<div><br>
<br>
On 1/24/2013 12:35 PM, Allan Sindelar wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div> Wrenches,<br>
We have years of installing 36-cell (12V) and
72-cell (24V) modules for battery-based
customers. Most of our systems are 24V or 48V
nominal. Over the last few years, sources of
conventionally-sized 72-cell modules have
dried up - as cells have increased in size,
most modules and most newer factory production
lines have either gone to 60-cell (20V)
modules, or 72 cells in 300+ watt ranges. It
seems that the formerly common 72 cell, 24V
modules in the 150-190 watt range, which are
well-suited to integrating into existing
systems, are no longer available.<br>
<br>
60-cell modules in the common 220-250 watt
range can't be added to an existing system
unless run through a dedicated MPPT charge
controller that can convert voltage, such as
an FM, XW60, Classic or TriStar; the added
cost of any of these controllers cancels out
the low prices of the modules.<br>
<br>
Who continues to manufacture 72-cell modules?
Which distributors carry them?<br>
I am aware of three options - are there
more?<br>
- Sunpower makes one module in the 245
watt range that can be used negative ground,
but it's very high efficiency (and with high
Voc/Vmp as well) and very pricey;<br>
- Sanyo/Panasonic has 225-240 watt
modules, but also quite premium and pricey;<br>
- Ameresco bought the rights to
manufacture many former BP modules, and I
think they make some. But we had to replace
lots of failed BP modules in that size range,
and are hesitant to use their technology,
fearing that the problems may persist in the
continued line.<br>
<br>
Thank you for any discussion and
recommendations.<br>
Allan<br>
<div>-- <br>
<font face="Times New Roman, Times, serif"><b>Allan
Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com" target="_blank"><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><a href="tel:505%20424-1112" value="+15054241112" target="_blank">505
424-1112</a></b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank"><u>www.positiveenergysolar.com</u></a></span></font>
<p class="MsoNormal" style="margin-right:722.25pt"><span style="font-size:10pt"><b><br>
</b></span></p>
<span style="font-size:10pt"><br>
</span> </div>
<br>
</div>
</div>
</blockquote>
</div>
</blockquote>
</div>
<br>
</div>
</div>
</div>
</div>
<br>
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