Sunny Boy Stats "final" [RE-wrenches]
Robert Warren
robertwarren at mail.com
Thu Apr 24 22:04:45 PDT 2003
Jeff, John Berdner, et al,
I don't think this issue is dead yet.
I have commissioned or installed around 300+ of the Sunnyboy inverters
in the last 2-1/2 years, over here in England, in my work at Solar
Century. We have a much greater variety of approved SMA inverters than
you do in the States, so they are not precisely the same animals.
I would have to go back through my records, but I am pretty sure the
failure rate I have seen is around 8 to 10%. This amounts to something
like 25 to 30 inverters I have had to send back for various reasons. A
couple of times, I have sent back a pallet with 8 or 10 of them. While
this seems like an alarmingly high failure rate, quite a few of them
were never installed. Before I install any of these inverters, I first
hook them up to a regulated variable DC power supply in the shop and
re-program them to the high and low voltage and frequency standards
which are presently required in the UK, quite different than the German
regs. SMA finally got around to providing a programming option for the
UK, as they have for the US, but I still like to know that an inverter
isn't DOA before taking it out to a job site a couple hundred miles
away.
Furthermore, quite a few of these inverters I returned weren't dead,
but I returned them because I found a huge variance on the spot value
reaadings for AC voltage. After setting up the parameters, I would look
at the "spot value" readings (using either a Sunnyboy controller or a
desktop computer to communicate via either Powerline, RS-232 or RS-485
as we use all types). If the inverter says its AC grid voltage is over 5
volts different than what my calibrated True RMS meter says, I would
reject it. This turned out to be a bit of a harsh practice, however, as
I was haveing to reject so many that sometimes we didn't have enough
stock to start a job. So I started letting them slide a bit, only
rejecting ones that were 8 to 10 VAC too high. Then I would adjust the
max VAC parameter a bit higher and note in my inverter log the
difference in values observed.
The main problem for me is that here in the UK, we are only allowed a
maximum VAC output of 253 VAC against the nominal grid voltage of 240. I
have personally visited most of our PV sites and routinely see grid
voltage around 246-250. As the inverter may be reading the actual grid
voltage of 248 as 253 if it has a 5 volt error, then it goes into high
AC shutdown mode. I have had numerous installations where the inverter
seldom or never ran, just because of this problem. All of my larger
installations have modem and remote dial-in capabilties, so sometimes I
have been able to dial in and remotely change the max AC parameter and
get the inverter to work again, in situations where performance was
spotty. I have complained numerous times about this to SMA, but never
got them to respond with the answer I wanted. I have several times asked
them to beef up their calibration Quality control, so I don't have to
deal with such problems. What they would do instead, was to send me a
new inverter promptly any time I sent one back, which was good.
Some of the inverter failures may have been due to electrical spikes
(one installation had 7 failures out of 30 inverters, but the apartments
were just a few blocks from a high voltage switching station. A couple
were due to installer errors. I must admit that I have seen a huge
improvement in inverter quality and lots of little detail improvements
over this period, and all in all, I am very impressed with the product.
I like them much more than anything I have used from US manufacturers,
excepting for inverters made by UPS manufacturers (I am factory
certified by Best and Toshiba).
What I would say to dealers, is, in addition to carrying a spare
inverter (since for you it is likely to be a 2500, is to carry a
Sunnyboy controller and spare Powerline modem to pop into the inverter
so you can check the performance and read your error messages from the
inverters on site. The self diagnostic features are quite helpful, and I
am sure they will get better.
I hope this is helpful.
Robert Warren
robertwarren at amil.com
Jeff Oldham wrote:
>
>
> It looks like this string has wound down. I've complied the numbers
> given by all and the average is 12.75% failure rate. Two other
> observations came from this - 1) a rather high DOA and 2)once fixed and
> opperating for a week or two there are very few problems thereafter. I'm
> sure we all would like to see inverters more reliable than this, but at
> this time all agree (including me) that SMA has the best product around
> and the service is hard to beat anywhere. We also have a manufacturer
> here that makes very generous, valuable and consistant contributions to
> this list, thank you John Berdner.
>
> The moral of the story and as John @ SMA has always been telling me -
> Always carry a spare inverter in your rig to the job sites.
>
> Thank you all for the feedback, what a great group!
>
> -jeff
> From the Solar, Wind and Hydro powered office of Jeff Oldham
What will we do if there is another fuel shortage?
Did you know that there is a pollution free, completely
renewable fuel which you can use right now in your own car?
Don't replace the engine, replace the fuel.
Check out my website on making your own fuel:
http://running_on_alcohol.tripod.com
robertwarren at mail.com
- - - -
To send a message: RE-wrenches at topica.com
Archive of previous messages: http://www.topica.com/lists/RE-wrenches/
List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm
Check out participant bios: www.mrsharkey.com/wrenches/index.html
Hosted by Home Power magazine
Moderator: michael.welch at homepower.com
==^================================================================
This email was sent to: michael_welch at sbcglobal.net
EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com
TOPICA - Start your own email discussion group. FREE!
http://www.topica.com/partner/tag02/create/index2.html
==^================================================================
More information about the RE-wrenches
mailing list