<div dir="ltr">The initial issue was concerned with waste power, but that presumes all power is priced evenly. Take a familiar situation, you specify and sell the system based on a number of 240W modules. Let's presume time passes and when you go to buy out the job, you find there is a deal on 260W modules which makes them as cheap as the 240W would have been. Why would you not just buy the larger output if all costs are the same. If they clip the inverter a little, oh well.<div>
<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Jan 28, 2013 at 7:35 PM, Nick Soleil <span dir="ltr"><<a href="mailto:nsoleil@enphaseenergy.com" target="_blank">nsoleil@enphaseenergy.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi John,<br><br><div><div>It's important to clarify that the "clipped" power does not
turn into heat within the microinverter. The microinverter only draws
enough current to achieve it's max output rating, and the remaining
current is "left in the module", so to speak. So, the heat generated at
peak times is the same, whether using a 260W module or a 280W module. </div><div><br></div><div>Many
string inverters actually work similarly. What's different for them,
however, is their overall thermal situation. The primary thermal driver
for a string inverter is the amount of heat generated by their
electronics, and the ability of their "fans & fins" to expel that
heat.</div><div><br></div><div>For example, a 5kW string inverter
generates ~200W of heat at peak, and it has fans and fins sized
accordingly. But, the effectiveness of the fans and fins depends on the
ambient temperature (and on elevation/air mass), and if your inverter
was operating at max power during hot weather (which would require
significant oversizing due to the modules' temperature derates), it
could exceed the capability of the fans and fins. This would then
require the inverter to ramp-down output. (Actually, some string
inverters can respond improperly--depending on whether their fan is
continuous, load-controlled or thermally-controlled--and actually fry
the electronics.)</div><div><br></div><div>But, the thermal environment of a microinverter is very different. </div><div><br></div><div>The
main thermal driver in our situation is actually the external
environment, not the electronics. Regardless of sizing ratio, an M215
generates less than 10 watts of heat at peak, whereas the heat radiated
from the module at peak times will be substantially greater than that.
Consequently, we've already over-engineered the microinverter for
extreme heat management, and the thermal effects of sizing ratio are
simply a drop in the bucket compared to the other factors.</div><div><br></div><div>For
that reason, we don't put limits in our warranty with regard to sizing
ratio (which contrasts with at least some string inverter warranties),
and we would not expect to see any microinverter ramp-down behaviors
driven by sizing ratio.</div><div><br></div></div><br></div><div class="gmail_extra"><br><br><div class="gmail_quote"><div><div class="h5">On Mon, Jan 28, 2013 at 11:06 AM, John Berdner <span dir="ltr"><<a href="mailto:John.Berdner@solaredge.com" target="_blank">John.Berdner@solaredge.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
<div>
<div><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Jason:<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Be careful of drawing false comparisons. There is no free lunch.<u></u><u></u></span></p><p class="MsoNormal">
<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Beyond the energy yield issues there are some reliability issues.<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">You should also consider that running an inverter flat out all the time will shorten it’s life (due to the Arrhenius effect). <a href="http://en.wikipedia.org/wiki/Arrhenius_equation" target="_blank">http://en.wikipedia.org/wiki/Arrhenius_equation</a><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Think of the inverter temperature in the same way you would the power output curve (the two are closely related). Moving the whole power curve up “more on the shoulders” also moves the whole temperature curve up as well.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The average lifetime (all this stuff is only probabilities) was projected with certain assumptions about how many hours at what temperature. As module sizes increase a given inverter will spend more time at a higher power level, i.e. runs hotter longer, which non-linearly reduces the life of the product.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Just my $0.02… With the high labor cost of replacement it might be better to undersize the module relative to the power electronics or vice versa. This may or may not increase the installed system cost depending on the products you choose. Running everything flat out all the time is probably not the greatest idea. <u></u><u></u></span></p>
<div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Best Regards,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">John Berdner<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">General Manager, North America<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
</div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><img alt="SmallBannerPictEngnew" border="0" height="113" width="468"><u></u><u></u></span></p>
<div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">SolarEdge Technologies, Inc.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">3347 Gateway Boulevard, Fremont CA 94538 USA </span><b><i><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#c00000">(*Please note of our new address.)</span></i></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><br>
T: <a href="tel:510.498.3200%2C%20X%20747" value="+15104983200" target="_blank">510.498.3200, X 747</a><u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">M: <a href="tel:530.277.4894" value="+15302774894" target="_blank">530.277.4894</a> <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p></div><p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a> [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Jason Szumlanski<br>
<b>Sent:</b> Monday, January 28, 2013 5:30 AM</span></p><div><br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] high insolation value and inverter undersizing<u></u><u></u></div><p></p><p class="MsoNormal">
<u></u> <u></u></p><div><p class="MsoNormal" style="margin-bottom:12.0pt">I found the latest module "rightsizing" paper by Enphase pretty interesting. It does stand to reason that there are a lot of hours in the day where the inverter is producing less than rated power, so increasing the module size makes sense. Obviously there is an optimum point in every system where clipping exceeds gains, but that's virtually impossible to nail down due to so many factors being involved. I think the point would be that PV mods are coming down in price so much that "rightsizing" is basically equivalent to "upsizing," within reason, of course. Spending an extra 25% on PV might increase the installed system cost by 5-10%.<u></u><u></u></p>
<div><div><div style="margin-bottom:6.0pt"><p style="margin:0in;margin-bottom:.0001pt"><strong><span style="font-size:10.0pt;font-family:"Verdana","sans-serif";color:gray">Jason Szumlanski</span></strong><span style="font-size:10.0pt;font-family:"Verdana","sans-serif""><u></u><u></u></span></p>
<p style="margin-right:0in;margin-bottom:12.0pt;margin-left:0in"><em><span style="font-size:10.0pt;font-family:"Verdana","sans-serif";color:gray">Fafco Solar</span></em><span style="font-size:10.0pt;font-family:"Verdana","sans-serif""><u></u><u></u></span></p>
</div></div></div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p><div><div><p class="MsoNormal">On Sun, Jan 27, 2013 at 6:00 PM, Marco Mangelsdorf <<a href="mailto:marco@pvthawaii.com" target="_blank">marco@pvthawaii.com</a>> wrote:<u></u><u></u></p>
</div><div><div><div><p class="MsoNormal">I have had a concern for a long time that as PV modules have gone up in output that there is inevitably going to be more and more clipping taking place as they’re paired with comparatively lower output inverters. In effect, matching, say. a 260-watt module with a micro inverter with a max output of 225 watts reduces that 260-watt mod to 225 watts. It’s not a matter of if clipping will take place, but how much and how much actual harvestable energy will be lost.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">Out here in the tropics, even in January with the lower sun angle, we see irradiance levels well above 1,000 watts/square meter range. Take a look at what I copied today from a weather station that we installed at nearby installation.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">Given the clipping issue inherent in using undersized inverters, it seems to me that moving to larger output micros makes a whole lotta sense. I’ve got one of the first installs using the Power-One 250-watt and 300-watt micros and am so far quite impressed. Why use a 225-watt rated micro with a 225-watt or higher output mod when larger micros are now readily available?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">What are the views out there regarding this clipping issue? Is it as minimal as our Enphase friends suggest in their latest white paper or more of an issue as I conclude?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">marco<u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal" style="background:white">
Environmentals from Weather Station at a Hilo, Hawaii installation<u></u><u></u></p><p class="MsoNormal" style="background:white"><b> </b><u></u><u></u></p><p class="MsoNormal" style="background:white">Sunday, January 27th 2013, 12:40:00 pm<u></u><u></u></p>
<p class="MsoNormal" style="background:white;vertical-align:middle"><u></u><u></u></p><p class="MsoNormal" style="background:white"> <u></u><u></u></p></div><p class="MsoNormal" style="background:white;vertical-align:middle">
<b>Ambient Temp.</b> 25.30 °C<u></u><u></u></p><p class="MsoNormal" style="background:white;vertical-align:middle"><b>Cell Temp.</b> 41.70 °C<u></u><u></u></p><p class="MsoNormal" style="background:white"> <u></u><u></u></p>
<p class="MsoNormal" style="background:white;vertical-align:middle"><u></u><u></u></p><p class="MsoNormal" style="background:white"> <u></u><u></u></p><p class="MsoNormal" style="background:white;vertical-align:middle"><b>Insolation</b> 127.81 kWh/m˛<u></u><u></u></p>
<p class="MsoNormal" style="background:white;vertical-align:middle"><b><span style="font-size:16.0pt">Irradiance <i>1,175.00</i> W/m˛</span></b><u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p></div></div></div>
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