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"Low Bid" is often the rule of the day, but so is 5 and 10 year
warranties, 20 year PPAs, maintenance agreements, and production
guarantees.<br>
A bit more money spent on an inverter that lasts longer is worth it.
<br>
Is buying a bigger inverter and running it at 60% of its rating
going to buy more MTBF (mean time between failures)<br>
or should manufacturers consider selling a premier line with better
cooling fans, and all the upgraded goodies you mentioned. (along
with possibly an extended warranty?)<br>
I've seen some very old inverters (Exeltech and Trace) still working
after 20 years, but those are indoors and not at full load every
day.<br>
Seems we need to do more to baby these Grid tie inverters (put them
in the shade, good air flow, surge arrestors, don't over load them,
etc.)<br>
<br>
Ray Walters<br>
<br>
On 8/19/2011 11:18 PM, Exeltech wrote:
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<td style="font: inherit;" valign="top">--- On <b>Fri,
8/19/11, Ray Walters <i><a class="moz-txt-link-rfc2396E" href="mailto:ray@solarray.com"><ray@solarray.com></a></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><a class="moz-txt-link-rfc2396E" href="mailto:ray@solarray.com"><ray@solarray.com></a></i></b>
wrote:<br>
<blockquote style="border-left: 2px solid rgb(16, 16,
255); margin-left: 5px; padding-left: 5px;"><br>
From: Ray Walters <a class="moz-txt-link-rfc2396E" href="mailto:ray@solarray.com"><ray@solarray.com></a><br>
Subject: Re: [RE-wrenches] Out of Warranty Inverter
Replacements<br>
To: "RE-wrenches"
<a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a><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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<br>
Making equipment more robust, yet constantly
lower in cost, are diametrically opposing
goals.<br>
<br>
<br>
Dan</td>
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