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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Carl,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Just to be clear, the performance tests mandated by the California Energy Commission, that all products in the U.S. follow, require that the maximum power rating is continuous (24/7). Actually, continuous means that it can operate for 3 hours straight at 40C (104F) (really hot). This does not mean it will last forever. That is an engineering decision on how close the manufacturer wants to operate their product up to maximum temperature of the components in the device. Some products may publish a maximum power that is higher than the maximum continuous power at 40C.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Bill.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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"'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Carl Emerson<br><b>Sent:</b> Tuesday, March 26, 2013 5:29 PM<br><b>To:</b> 'RE-wrenches'<br><b>Subject:</b> Re: [RE-wrenches] P1 micro performance<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'>Friends,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'>Keeping the record straight…<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'>I need to say that I have had correspondence ‘off list’ from a development engineer from a prominent manufacturer who assures me that his product is designed to run ‘flat out’ 24/7. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'>The unit in fact is just coasting at it’s maximum power rating. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'>This allows for a projected life matching that of the PV.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'>In this case power clipping will not shorten the products life.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'>I am unable to confirm if all manufacturers are taking this approach, buyer beware…<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:14.0pt;font-family:"Arial","sans-serif";color:blue'><o:p> </o:p></span></p><div><p class=MsoNormal><span lang=EN-GB style='font-family:"Arial","sans-serif";color:black'>Regards<br>Carl Emerson</span><o:p></o:p></p></div><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Nick,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Is Enphase going to be introducing to market any time in the near-term a new micro with a higher output? It seems very likely that the trend toward higher output mods will continue. The M215 will surely be left behind to a greater degree as this trend continues if there are higher and reliable and comparably priced, on a dollar/watt basis, micros available.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>marco</span><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'><o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>Hi Carl, Marco, and Wrenches,<o:p></o:p></p></div><div><p class=MsoNormal>As a longtime installer, I understand your point of view. Historically, I designed my string and microinverter systems with the same consideration for maintaining conservative DC to AC ratios. That being said, the costs of modules have decreased significantly and the dynamics have changed. Solar companies should be focused on selling systems that offers a great rate of return. Maximizing the customer's investment is most important. Isn't that what your customer wants?<br><br>What Enphase is encouraging is the development of cost effective PV systems that will generate a healthy return. Considering that the modules are only 20% of the total system costs today, it is smart to give up 0.2% or more of the module production to lower the overall system costs by 5-10%. The NEC requires that the AC panel boards, conductors, and circuit breakers are sized to the inverter continuous output current rating. We should be maximizing this infrastructure.<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'>The data available indicates that when a system is installed with a 1.2 to 1.25 DC to AC ratio, it will rarely operate at peak output. Installing a PV system with a 1.25 DC to AC ratio is not driving the equipment to the maximum. In the case of the Enphase M215s; they are designed to operate continuously at peak output, so reaching that level a few hours in the first years is not problematic. To be clear, this limiting will occur the most during the spring months, because you have a combination of both cool weather and high irradiance levels.<o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'>As Dan mentioned, this applies to string inverters as well as microinverters. One of the most common system designs of the early US grid-tied market was installing 18- 165 watt modules on an SWR-2500. I designed hundreds of projects like that. That was a ~1.2 multiplier, and was at a time when the modules cost $5 per watt; not $1 per watt. Why be more conservative now?<o:p></o:p></p></div></div><div><div><div><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB> </span><o:p></o:p></p></div></div></div></div></div></div><pre><o:p> </o:p></pre></div></body></html>