[RE-wrenches] Abysmally low production from FLEXpowerTWO GVFX3648system

Sun Apr 8 21:04:03 PDT 2012

Bob,

There are a lot of settings that could influence your numbers.

I guessed at Yakima, WA for the PV Watts location and using 77%, I got:
239kwh for December,
254kwh for January
361kwh for February &
531 for March.

I would predict you should have at least generated most of this amount per
month, not half as much for the whole quarter.

1. Make sure SellRE is enabled: ADV/FX/SELL/Grid Tie Authority = Yes
(instead of NO SELL).
2. Double check the ADV/MATE/PG4/FN-DC Advanced Grid-Tie Authority settings
for set correctly or off. This setting allows the inverter to absorb the
batteries before enabling SellRE. If the charge is set for a 3 hour Absorb
before selling, that can put a huge dent in production. You might consider
turning this off or understanding if it intelligently shortens absorb or set
absorb to a short time, to hasten sell.
3. Verify the Sell voltage is appropriate. I typically use the low side of
the Float voltage printed on the battery (52.8 [whatever Outback allows])
and disable/lower Float on the Inverter's Charger.
4. Also verify the Float and Absorb settings on the charge controller. I use
the high side of those same battery numbers (53.6 [whatever Outback
allows]). In a normal day, you don't want the charge controller thinking it
is done, but you want the inverter to do all it can. If the Charge
Controller goes to Float, the inverter will have nothing the sell, so I set
the charge controller Float a little higher than SellRE / Inverter Float. Of
course, it should never get out of Absorb anyway, but just in case.

Also keep in mind that you are splitting the selling across two inverters
wherein each one is 93% efficient (from the spec sheet) and I think that is
a peak value. So add up the losses down the chain to see if 77% is
appropriate. I have a site where I get 70% in the Winter and about 82% in
the Summer due to the tilt angle of the array. It is tough to get above 77%
PV watts vs. AC watts.

Does the site have the MATE3 so that you can some daily logs? Monitoring is
the key to success, in my opinion. How can you know where your are going if
you don't know where you've been?

On another angle. During a bright sunny day at solar noon, open the combiner
box and verify with a DC Amp Clamp that all is as expected, while the
outback is Selling / FM80 is Absorbing as much as possible (expect 3.1-3.5kw
on the FM80). Go off-grid and turn on a large load if necessary.

Third Angle. Check the Grid Voltage while the Outback is selling at much as
possible. Make sure it is not going above 129 VAC, or so (Stop Sell Reason
other than 8, for instance).

Good luck,

Maverick

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Bob Clark
Sent: Sunday, April 08, 2012 9:43 PM
To: RE-wrenches at lists.RE-wrenches.org
Subject: [RE-wrenches] Abysmally low production from FLEXpowerTWO
GVFX3648system

Dear Wrenches:

What am I not seeing with this situation?

Only 133 DCkWH (120 ACkWH) during mid-December through April 6 (at least
that is what the mate and the MX80 CC say).  PVWATTS predicted ~600 ACkWH.

Here are the major components of the system:

24 - Silicon Energy 190W solar modules in 8 series of 3 modules for 4560W
nominal

1 - Midnite Solar, Combiner box, MNPV12 with 8 circuit breakers (one for
each string)

1 - MX80 charge controller

16 - Concorde SunXtender Sealed AGM Battery, 6V, 405Ah, L16, PVX-4050HT (2
parallel series of 8 batteries for 48V and 810 AH)

1 - Outback FlexNet DC System Monitor, FN-DC

2 - GVFX3648 inverters

1 - Mate2

1 - HUB10

1 - Remote Temperature Sensor

The insolation this winter has been, if anything, more than usual.  The
electrical usage noted on the utility bill was approximately 170 ACkWH more
than the same winter period last winter.  No appreciable change in usage
pattern this winter compared to last winter (in fact, if anything, there has
been less use this winter).  Everything appears to be functioning (normally,
I think).

What is going on?  It cannot just be a malfunctioning utility meter.  It
seems to me that regardless of the functionality of the utility meter, the
Mate and the MX80 should show greater production.

What is being overlooked?

Thanks for your help.

Bob Clark

SolarWind Energy Systems, LLC

(509) 826-1259

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