<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">--- On <b>Fri, 8/19/11, Ray Walters <i><ray@solarray.com></i></b> wrote:<br><br>> So is it fair to say that an inverter run at half it's design
capacity<br>> might last twice as long? <br><br><br>It will last longer .. but as to how much longer .. there's no firm rule. Much depends on how well the inverter is designed and built in the first place.<br><br>Lifetime of some components is affected by temperature. In turn, the temperature of various components is in part determined by the power level at which the inverter is being operated. Other factors are: 1) the ambient temperature of the inverter's environment; 2) the inverter's access to free-flowing air.<br><br>Other considerations that come into play for component longevity are how closely a component is operated to its maximum ratings, and for how long a period of time it spends at the maximum(s).<br><br>Well-designed inverters .. ones that are designed from the onset for longevity .. will be made to operate at their full-rated output at their maximum ambient temperature, and do so without time limit. They will
use high quality components that are well within their operating margins. This means parts that cost more.<br><br>A manufacturer may elect to skimp on the ratings of parts you can't readily see .. such as the voltage breakdown rating of the transistors. Lower voltage versions cost less, but aren't as robust, and are more likely to fail in the event of a voltage transient on the power line than higher voltage versions. Conversely, higher voltage versions tend to be slightly less efficient than lower voltage parts, so once again the manufacturer is boxed in.<br><br>Can inverters be designed and built that will last 20+ years? Yes. Exeltech has been doing it for more than 21 years. Problem is .. well designed and well built inverters cost a little more, and the American public has been taught to shop almost exclusively based on price alone. I'm sure you and the other Wrenches see this all the time in the method
most commonly used for awarding projects -- the infamous two word qualifier: "Low bid".<br><br>Ray .. you asked very simple yet most excellent question. I wish the answer were equally as simple...<br><br><br><br>Regards,<br><br><br>Dan<br>Sr. Engineer, Exeltech<br><br><br><br><br>--- On <b>Fri, 8/19/11, Ray Walters <i><ray@solarray.com></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><br>From: Ray Walters <ray@solarray.com><br>Subject: Re: [RE-wrenches] Out of Warranty Inverter Replacements<br>To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org><br>Date: Friday, August 19, 2011, 3:40 PM<br><br><div id="yiv1706892972">
HI Dan;<br>
<br>
So is it fair to say that an inverter run at half it's design
capacity<br>might last twice as long? What in your opinion would be the<br>sweet spot of enhanced reliability
but still reasonable cost?<br>
<br>
I'm sure Exeltech just like everyone else (including me) are being<br>squeezed from all sides to keep lowering cost. Its just ridiculous,<br>and a long term player like Evergreen Solar
going under should<br>be a real wake up call for all of us. The solar industry's current<br>race to the bottom is sacrificing long
term reliability (and our future)<br>for lower $$/ watt today. I actually wonder if slowing some subsidies<br>might make for a saner
playing field.<br>
<br>
Ray Walters<br>
<br>
<br>
On 8/19/2011 12:33 PM, Exeltech wrote:
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Making equipment more robust, yet constantly lower in
cost, are diametrically opposing goals.<br>
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<br>
Dan</td>
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