Fellow Wrenches,
No stones from this Missouri P.E. Perhaps if more Greybeards gave such
candid comments it might influence others toward something other than a
race to the bottom.
Bill Loesch
Solar 1 - Saint Louis Solar
314 631 1094
On 24-Mar-13 12:07 PM, Ray Walters wrote:
Hear, Hear, Carl.
That has also always been my experience as well. In my off grid work,
reliability trumps budget, and I almost always over size charge
controllers, relays, inverters, fuse holders, etc. Most failures seem
to be related to pushing the design limits of the equipment.
I spent the past year working on multi MW systems, where they saved
every penny possible. The inverters were undersized by 20 to 25% but
sitting in unairconditioned enclosures. Even better that the
projected 30 year life of the system did not even include inverter
replacements.
I'm sure I shall be stoned to death for saying this, but basically the
grid tie solar community just doesn't have enough experience under its
belt yet to have seen what we learned a decade ago in the off grid world.
When they start putting call backs, down time, inverter replacements,
and the related loss of respect and business into their spread sheets;
they'll start oversizing the inverters more, like you, Marco, and many
of us already know.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 3/23/2013 7:19 PM, Carl Emerson wrote:
Friends,
I am a little puzzled by this topic.
What has happened to the good engineering practice of sizing
electronic equipment so that it is not driven to the maximum.
My understanding is that the MTBF increases significantly the harder
you drive the unit.
This seems to be a case of overdriving the units for short term gain.
*Carl Emerson*
*Free Power Co. *
*Auckland N.Z.***
What I *can't* answer is the long-term effect this may have on the
overall
life of the inverter. THAT depends on various intricate design
considerations
that went into creating the inverter in the first place.
Dan Lepinski, Senior Engineer
Exeltech / Exeltech Solar Products
With 41 years experience as a design engineer in solar energy.
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