<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.6001.18183" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV>I am working on a residential project that seems perfect for the Enphase
product (long array to interconnect point run). Researching the product, I came
across one of their website videos (nicely done) claiming an
"MTBF of 119 years" without any explanation as to what that actually means -
that is - how did they arrive at that assumption/prediction. I googled
"mean time between failures". Got this - h<A
href="http://www.ptsdcs.com/whitepapers/57.pdf">ttp://www.ptsdcs.com/whitepapers/57.pdf</A>
- a white paper that briefly explains different methods to predict or assume
system and or component failures/reliability. Interesting. The conclusion of
this white paper:<FONT face=Arial size=1><FONT face=Arial size=1>
<P align=left>MTBF is a “buzz word” commonly used in the IT industry. Numbers
are thrown around without an</P>
<P align=left>understanding of what they truly represent. While MTBF is an
indication of reliability, it does not represent</P>
<P align=left>the expected service life of the product. <STRONG><EM>Ultimately
an MTBF value is meaningless if failure is undefined and</EM></STRONG></P>
<P><STRONG><EM>assumptions are unrealistic or altogether missing.</EM></STRONG>
(emphasis mine).</P>
<P><FONT face=Calibri size=3>So my question is this: Are <EM>any</EM>
manufacturers that use MTBF as a selling point willing to disclose how
these values were obtained? Not picking on Enphase....I will contact them with
to ask. IMHO, with the new stuff that will be thrown at us over the
coming years, we should expect real numbers from anyone using MTBF to tout their
stuff. </FONT></P>
<P><FONT face=Calibri size=3>Stepping off soap
box.</FONT> </P></FONT></FONT></DIV>
<DIV>Holt E. Kelly<BR>Holtek Fireplace & Solar Products<BR>500 Jewell
Dr.<BR>Waco TX. 76712<BR>254-751-9111<BR><A
href="http://www.holteksolar.com">www.holteksolar.com</A><BR></DIV></BODY></HTML>