SB's in high temperature (was lemmings) [RE-wrenches]

Thu Feb 6 15:22:31 PST 2003

Joel,

There is no consistent rating criteria for inverters so take your pick on
what rating you would like.

The 2.5 kW rating is for 25C as I understand it (indoor conditioned space).
Most inverter manufacturers use this as their rating criteria (for obvious
reasons). This is not nearly as rediculous as rating a PV module at
25C--what a joke that is.

If all manufacturers used 45C as a rating criteria we would find very
different rating numbers.

Moral of the story is you must know a lot about the inverter's
characteristics before you can start designing an array for it. Taking a
simple rating and taking off with a design simply doesn't work for many
inverters.

Bill.

-----Original Message-----
From: Joel Davidson [mailto:joeldavidson at earthlink.net]
Sent: Thursday, February 06, 2003 3:05 PM
To: RE-wrenches at topica.com
Subject: Re: SB's in high temperature (was lemmings) [RE-wrenches]

John,
I think you will sell just as many Sunny Boy inverters if you rate them 2.2
kW instead of 2.5 kW.
Best regards,
Joel Davidson

jberdner at sma-america.com wrote:

> Graham:
>
> While you can use the Sunny Boy + Breeze scenario there is another more
> conservative approach is reliability and longevity are of paramount
> concern.
> If you undersize the array by 10 to 15% there should be no issue at 103
> F.  This approach adds no additional hardware and not pushing the
> inverter to its limits will certainly extend it's life. There is a rule
> of thumb in power electronics (I forget who's rule it is) - for every
> 10C decrease in temperature the life is doubled. This is true for all
> power electronics not just our inverters.
>
> Fan Life - In building the Sunny Breeze we selected a fan with 30 k
> hours MTBF.  The 2 to 3 year estimate for life is out estimate for
> outdoor, unprotected mounting.  If mounted indoors it will run more
> frequently but the life of the fan should certainly be well beyond the
> warranty period.
>
> If you have any questions, or if I can be of any further assistance,
> please do not hesitate to contact me.
>
> Best Regards,
>
> John Berdner
>
> SMA America, Inc.
> 12438 Loma Rica Drive, Unit C
> Grass Valley, CA  95945
> 530.273.4595 (voice)
> 530.274.7271 (fax)
>
> -----Original Message-----
> From: Graham Owen [mailto:graham at solarexpert.com]
> Sent: Thursday, February 06, 2003 8:49 AM
> To: RE-wrenches at topica.com
> Subject: RE: Lemming's [RE-wrenches]
>
> Hi Matt,
>
> I now have full confidence selling and installing SB's as reliable
> devices.  I knew this product had a solid background in Germany and well
> as other European countries my concern was with how they would hold up
> under the extreme summertime heat in the San Fernando Valley.  I knew a
> lot of guy's that installed ST's and when summer arrived with
> temperatures over 103 degrees the problems began.  I still have concerns
> about fully loading SB's to the max and using the Sunny Breeze fan,
> which I think I recall being told, should last 2-3 years.  As a
> contractor taking advantage of emerging renewable incentive programs, I
> have to provide a full five-year warranty.  Undoubtedly there will be
> service calls in the future. A problem will occur if and when the
> subsidies have dropped below a level that provides enough incentive for
> new PV construction.  This will present a dilemma for solar contractors,
> how do we provide free service calls if there is no more income being
> generated by new PV system installations?  There are many reasons why I
> am trying to be as careful (slow and methodical) as possible so as not
> to fall into the sea as Bill suggested, rather I would rather be one of
> the slow lemmings, which stay around to reproduce in the future.
>
> Graham
>
> -----Original Message-----
> From: matthew tritt [mailto:solarone at charter.net]
> Sent: Wednesday, February 05, 2003 8:17 PM
> To: RE-wrenches at topica.com
> Subject: Re: C40's and SW's [RE-wrenches]
>
> Hi Graham,
>
> I can't see why you would consider your customers to be Guinea Pigs when
> installing SBs for them, considering the lengthy experience with the
> units in Germany and elsewhere. The actual award for The Biggest
> Experiment should go to either Advanced Energy or Xantrex. No? We all
> have installed plenty of those and replaced almost as many. I wonder
> what will happen when the repaired GC's start crapping out! Big fun for
> sure. I told one of my customers about the bankruptcy and I got the
> strangest look! :-)
>
> Matt T
> ----- Original Message -----
> From: "Graham Owen" <graham at solarexpert.com>
> To: <RE-wrenches at topica.com>
> Sent: Wednesday, February 05, 2003 2:02 PM
> Subject: RE: C40's and SW's [RE-wrenches]
>
> > Hi Bill,
> >
> > Thanks for the sound advice.  When I wrote my long-term business plan,
>
> > with a lot of lessons learned from the 1986 collapse of the solar
> > industry, I vowed to only install products with at least two years of
> > untroubled local performance.  This may sound crazy to some, but I
> > have only just recently started working with SB inverters.  I don't
> > like making my customers guinea pigs.
> >
> > Thanks again, from a slow lemming,
> >
> > Graham
> >
> >
> > -----Original Message-----
> > From: Bill Brooks [mailto:billb at endecon.com]
> > Sent: Wednesday, February 05, 2003 1:42 PM
> > To: RE-wrenches at topica.com
> > Subject: RE: C40's and SW's [RE-wrenches]
> >
> >
> > Jay,
> >
> > With all due respect to the Outback folks, for grid-tied systems I
> > would not be so quick to toss my C-40s for a Max Power controller,
> > whether MX-60 or SB50. The additional cost may or may not pay for
> > itself over time and the reliability is an unknown. I don't think
> > anyone has enough hard data to make that blanket assessment.
> >
> > Our industry has been so quick to run like lemmings to the sea every
> > time a new idea or product comes on the market. I always like to ask
> > the lemmings why they are running so fast, where they are going, and
> > for what reason. They seldom can provide me with good information to
> > join them.
> >
> > Bill.
> >
> >
> > -----Original Message-----
> > From: Jay Peltz, Peltz Power [mailto:jay at asis.com]
> > Sent: Tuesday, February 04, 2003 6:30 PM
> > To: RE-wrenches at topica.com
> > Subject: Re: C40's and SW's [RE-wrenches]
> >
> >
> > I think that any discussion of C-40's on large arrays, especially
> > intertie is a moot point.
> >
> > Most interties are pretty large and so the use of a MPPT controller is
>
> > very cost effective and is any easy swap out.  ( especially as the
> > MX-60 fits the same KO's)
> >
> >
> > In regards to the higher voltages equalling higher power, yes but I
> > have never seen any change in the output of the SW with the higher
> > input voltages.
> >
> > Peace,
> >
> > jay
> >
> > Peltz power
> >
> > ----- Original Message -----
> > From: "Jeffery Wolfe, Global Resource Options"
> > <jeff at globalresourceoptions.com>
> > To: <RE-wrenches at topica.com>
> > Sent: Tuesday, February 04, 2003 11:29 AM
> > Subject: RE: C40's and SW's [RE-wrenches]
> >
> >
> > > Bill,
> > >
> > > Although you're right that the C40 should never control, the point
> > > of the higher voltage settings is to make more power. We all know
> > > that the PV's will put out more power at higher voltages, so setting
>
> > > the inverter
> > higher,
> > > for float, is better. We also need to balance this with battery high
> > limits,
> > > and the fact that you need a pretty significant "dead band" in the
> > > control setpoints between the C40 and the Trace, due to inaccuracies
>
> > > in the
> > voltage
> > > meters in both units. (Trace told me 1.5 V, I'm typically using
> > > about 1.0 V).
> > >
> > > The 53.6VDC default on the inverters is also on the very low side of
>
> > > where we're floating batteries, even on-grid, today. We're moving
> > > hotter, more like 54.8 to 55.2. Batteries that float all year long
> > > tend to have
> > sulfation
> > > problems, and it seems that the hotter setpoints help reduce this.
> > > (Along with the little black boxes.) Couple this with the fact that
> > > on-grid
> > higher
> > > float voltages are going to produce more power, the case is made for
> > setting
> > > the floats about as high as the manufacturer's will let you. We do
> > > use
> > bulk
> > > mode, as it's good (IMHO) to bulk the batteries occasionally. So we
> > > set
> > the
> > > bulk up at about 58 VDC. This then pushes the bulks on the C40's up
> > > to
> >
> > > 59
> > to
> > > 59.5, in order to provide as much dead band as possible.
> > >
> > > We've got three years on our double C40 / SW system, as well as
> > > several others around the area. The low set points "work", but are
> > > not
> >
> > > the best
> > for
> > > power production (remember, we all complain about power production
> > > on PV systems), and are not necessarily the best for battery life.
> > >
> > > I do agree that the C40 float and bulk can be set the same, but it's
>
> > > more like setting the float to the same as a more typical bulk,
> > > rather
> >
> > > than the other way around.
> > >
> > > I also always use a Fluke to set up the C40 (and any other
> > > controller). I never trust the little dials or displays. They can be
>
> > > wrong (on any controller).
> > >
> > > Jeff
> > >
> > > -----Original Message-----
> > > From: Bill Brooks [mailto:billb at endecon.com]
> > > Sent: Tuesday, February 04, 2003 1:10 PM
> > > To: RE-wrenches at topica.com
> > > Subject: RE: C40's and SW's [RE-wrenches]
> > >
> > >
> > >
> > > Graham,
> > >
> > > I believe that bulk charging is meaningless in a grid-connected
> > application.
> > > Since the system is floated all the time, except during a power
> > > outage,
> > the
> > > focus is on the float settings. I would set the bulk timer on the
> > > inverter to 0:00 so it automatically goes to float. The default for
> > > the inverter is 53.6 Volts for float and I think that is fine for
> > > most
> >
> > > lead-acid
> > batteries.
> > > The key is making sure the C-40 is set at least one volt higher. It
> > > is
> > also
> > > critical that all controllers and inverters have temperature
> > > compensation probes installed and sensing basically the same
> > > temperature.
> > >
> > > Finally, check the C-40 while operating to make sure it is not
> > controlling.
> > > By testing the voltage drop across the C-40 positive battery and PV
> > > array inputs, you can tell whether it is controlling. The voltage
> > > should always
> > be
> > > below 0.75 Volts, otherwise it is controlling. It should only
> > > control in
> > an
> > > outage. Set the C-40 bulk at the same as the float, since the array
> > > should not be bulk charging the battery anyway. Bulk charging
> > > doesn't help a battery that stays at float all the time. It can
> > > actually hurt a VRLA battery by overcharging it if you allow it to
> > > bulk for more than a
> > half-hour
> > > or so. Hope that helps. Others may see it differently but I have
> > > over four years of grid-connected experience with my C-40s and SW.
> > >
> > > Bill.
> > >
> > >
> > > -----Original Message-----
> > > From: Graham Owen [mailto:graham at solarexpert.com]
> > > Sent: Monday, February 03, 2003 9:01 PM
> > > To: RE-wrenches at topica.com
> > > Subject: C40's and SW's [RE-wrenches]
> > >
> > >
> > > Dear Colleagues,
> > >
> > > I need some Wrench assistance with a PV service call, for the
> > > Xantrex Power Module system (or power panel for that matter), you
> > > have to set the C40 charge controllers and the SW inverter so that
> > > the inverter can sell PV power to the grid without the controllers
> > > restricting current into the inverter in the first place. I am
> > > trying to determine
> >
> > > which set of values works the best.
> > >
> > > Are these good figures?
> > >
> > > C40  bulk   56.0
> > >      float   55.0
> > >
> > > inverter bulk  54.0
> > >        float   53.2
> > >
> > > Thanks in advance!
> > >
> > > Graham
> > >
> > > P.S. Joel, I am working on finding your CPUC answers, I was working
> > > out of town today.
> > >
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