[RE-wrenches] Electrolytic Caps vs. Thin Film Caps

[Drake]

>Dave,

That is really good news. I went through this with Steve Jefferson 
and SMA recently.  They said that -13F was the limit.  Steve has 
posted to this effect on the list, but I couldn't find it in the 
archives.  The recommendation was that I get a Canadian model, but 
was not able to.  Where we are, it seldom gets below zero, but has 
historically gotten to -26 officially, and according to many it has 
gotten below - 30.  The customer has agreed to shut down the outdoor 
unit if it gets below -10F.  It would be good to know that SMA's 
recommendations are over cautious.  What is the coldest you have seen 
your inverters operate at?

Thanks,

Drake


>Drake,
>
>Before installing Sunny Boys outside I did some checking several 
>years ago. I spoke with some installers in cold locations in the USA 
>and also spoke with contacts at SMA. The word back then was although 
>the manual states -13F, they felt the SB's would be OK outdoors here 
>in Vermont. I also go the go ahead from Solectria and 
>Fronius.  James Worden, top boss at Solectria said -40F. The Fronius 
>engineer told me that the electronics in their inverters were 
>basically the same components that they use in their welders, and 
>that the welders sit outside in Siberia, in the winter.
>
>We try and install inverters in the basement, or garage, whenever 
>possible but have many outdoors with no problems so far.
>
>All Earth Renewables have been installing hundreds of trackers here 
>in Vermont and they all have Sunny Boys mounted on the pole.
>
>Best,
>Dave
>
>
>From: re-wrenches-bounces at lists.re-wrenches.org 
>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
>Sent: Wednesday, January 18, 2012 6:47 PM
>To: RE-wrenches
>Subject: Re: [RE-wrenches] Electrolytic Caps vs. Thin Film Caps
>
>The SMA inverters will suffer capacitor damage if operated below 
>-10F, from what I've been told.  Do you have different information?
>
>At 09:19 AM 1/15/2012, you wrote:
>
>Hello David,
>
>The minimum temperature rating for grid-tied inverters
>is dependent on the manufacturer's specifications.  It's
>a choice they make as a part of the product design
>and certification.
>
>The manufacturer must specify the coldest temperature
>as a part of their UL1741 certification effort, and
>that's the coldest to which it will be tested and
>verified as operational by the UL certification
>laboratory (NRTL).  Will it operate below the min
>temperature spec?  It might.  But then again, it's
>not verified to do so.  Some bad things can happen
>if the components don't handle cold very well, and
>power is applied (such as actual failure of parts.)
>
>Quality electrolytic capacitors are generally rated
>to -40C (which also happens to be -40F).  Film caps
>are often rated for temperatures below -40C, but at
>-40C, other components such as microprocessor clock
>crystals and many integrated circuits will fail to
>operate, so the point of film caps being rated for
>colder temperatures than electrolytic caps is moot.
>
>Note this is "fail to operate", not "fail".
>
>Cold-temperature components rated to -55C *could* be
>used in inverter construction, but parts of this type
>add cost (sometimes considerably) to the finished
>product price.
>
>
>By the way .. to your point of cold temperature specs
>not appearing in writing ...
>
>Our PVAC Modules *are* rated to operate at -40C, and
>have been tested to that temperature by the UL test
>lab.  This rating is stated in writing in our brochures
>as well as the PVAC Module Installation Manual/User's
>Guide.
>
>
>Dan
>
>
>
>--- On Sun, 1/15/12, Dave Palumbo <dave at independentpowerllc.com> wrote:
>
> > From: Dave Palumbo <dave at independentpowerllc.com>
> > Subject: Re: [RE-wrenches] Electrolytic Caps vs. Thin Film Caps
> > To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> > Date: Sunday, January 15, 2012, 7:32 AM
> > Dan,
> >
> > Any worries with inverters located out in 30 below zero
> > temps with either Electrolytic Caps or Film Capacitors?
> > It's very cold here this AM (minus twenty something F)
> > and it makes me wonder about all the inverters, both
> > micro's and string, outside in cold weather areas. We've
> > been told in the past by SMA, Fronius and Solectria that
> > we should be good down to 40 below, although this is
> > typically not found in their technical documents in
> > print.
> >
> > David Palumbo
> > Independent Power LLC
> > 462 Solar Way Drive
> > Hyde Park, VT 05655
> > <http://www.independentpowerllc.com/>www.independentpowerllc.com
> > NABCEP Certified PV Installer
> > Vermont Solar Partner
> > 24 Years Experience, (802) 888-7194
>
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Drake Chamberlin
ATHENS ELECTRIC LLC
OH License 44810
CO license 3773
NABCEP Certified PV
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