[RE-wrenches] Fwd: Outback Grid Problems

Mon Apr 5 10:02:10 PDT 2010

Here is a bit more on how RE-BULK and RE-FLOAT interact with the ABSORB
timer. All battery voltages are default and are given as 12VDC nominal,
multiply by 2 for 24V and 4 for 48V systems. All of the following is
true for grid-tie GV or GT FXs only. 

Definitions: 

BULK - Constant high current increasing battery voltage to reach
absorption stage. 

Absorption (ABSORB) - Constant high battery voltage (target 14.4 volts),
tapering current as battery capacity is filled. FX can charge or sell to
this voltage target. 

FLOAT - Charging cycle is complete from absorption stage, constant low
voltage (default 13.6 volts) trickle charge to maintain full battery. FX
can charge or sell to this voltage target. 

SellRE - Charging cycle also completed, constant low voltage (target
13.0 volts) target similar to Float. Sell RE is typically set lower than
float in order to minimize trickle charge to battery and force more
renewable energy to be exported from the FX inverter. FX can only
sell(not charge) to this voltage target. 

Equalize (EQ) - High voltage (target >15 volts) over charge of the
batteries meant to bubble electrolyte which stirs it up to maintain
equal concentration throughout the battery, and to create equal cell
voltages throughout the complete battery string. FX can charge or sell
to this voltage target. 

Pass thru - the FX is not converting any power and is silent 

All the stages above have target DC voltages associated with them. For
instance, if the FX is in Float mode, the target voltage for the battery
is 13.6 volts. While grid is available the FX can draw current from grid
to maintain 13.6 volts. If a DC renewable energy source is supplying
enough power to bring the batteries above the 13.6 volt target, the FX
can send current to AC loads or back out the grid input to keep the
battery at 13.6 volts. The FX is a bi-directional power conversion
device that will do everything possible to maintain 13.6 volts. 

Without grid input, the FX will not be able to actively maintain the
battery voltage at the current target, although the FX will still go
through the same stages, keeping track of battery target and timers. If
the DC sources are less then the AC load demands, the battery voltage
will fall. This can trigger a REFLOAT or REBULK dependent on how low the
battery voltage falls. Conversely, if the DC sources exceed the AC load
demands, the FX cannot maintain the battery voltage at any specific
target. Battery voltage will rise to what ever voltage the DC source
controller allows. 

Typical FX charger behavior: 

On initial DC power up of all grid-tie FX inverters, a 1 hour stock
absorption exists. Once AC power has been accepted by the FX, the BULK
cycle begins. 

After the battery voltage reaches the Absorption set point, the
absorption timer starts counting down and maintains absorption voltage
for the absorption time. Watching the absorption time is the indication
of how long the FX will be in the absorption mode. 

After the absorption mode is finished, the next stage is Sell RE. Sell
RE is a target that the FX cannot charge too, but can export renewable
energy if the source is powerful enough. Towards the end of the day,
typical renewable energy, like solar, is not available so the FX cannot
export any more power. In this event the FX will go silent/passthru,
which means it stops any power conversion. 

The battery usually still has small DC loads, so battery voltage may
slowly fall during the night. If the battery voltage falls below the
RE-FLOAT setpoint (12.5 volts) then the FX will transition to the FLOAT
stage and charge the battery to the FLOAT target (13.6 volts) for the
FLOAT time (1 hour). After the FLOAT timer has expired, the FX returns
to the SellRE stage and/or silent/passthru. 

If the battery falls past the REFLOAT setpoint, below 12.4 volts (which
we call RE-BULK), the FX will change to the BULK stage and the
absorption time remaining will start counting up. The absorption time
remaining will count up in real time as long as the battery voltage is
12.4 volts or below. The absorption time remaining counts in double time
if the battery voltage is less than 12.0 volts and counts in quadruple
time if battery voltage is less than 11.6 volts. In other words the
lower the battery voltage goes the more time the system will have to
remain in the absorption stage up to the absorption time setpoint. 

When charging sources (grid or renewable energy) are available again
then the FX can satisfy the absorption stage and continue on to the
SellRE stage again. 

Although the stages may seem confusing, they are all dependent on
battery voltage and what target the FX has. The status/meters 1st screen
top line always tells you what the FX is doing and what the target is.
The first word is what the FX is actually doing (PASSTHRU, CHARGE, SELL)
and the second word is the target (BULK, FLOAT, SELLRE, and EQ) where
the FX wants to be. Other sources/loads in you system can achieve these
targets besides the FX. All timers for any particular stage can be
satisfied by the target voltage being maintained for that stages time.
The only stage that has no timers associated with it is SellRE. 

One more thing to keep in mind, charger modes (BULK, ABSORB, FLOAT) take
precedence over SELLRE. Setting SELLRE at or below REFLOAT or REFLOAT at
or below RE-BULK, will cause unusual system behavior.

Steve Higgins. 

Sr Application Engineer. 

Sub-Saharan Africa Business Dev Mgr. 

Outback Power Systems. 

 19009 62nd Ave Ne 

Arlington Wa 98223

360-618-4313

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray
Walters
Sent: Monday, April 05, 2010 8:34 AM
To: RE-wrenches
Subject: [RE-wrenches] Fwd: Outback Grid Problems

Here's the latest comments from my customer on this. Seems to be just a
problem under reduced array output.

Thanks again for everybody's valuable input.

R. Walters

ray at solarray.com

Solar Engineer

Begin forwarded message:

From: "Roger L. Johnson" <rogerjohnson at itltd.com>

Date: April 5, 2010 9:02:03 AM MDT

To: Ray Walters <ray at solarray.com>

Cc: Andy O'Reilly <andy at positiveenergysolar.com>

Subject: Re: [RE-wrenches] Outback Grid Problems

Ray - I appreciate all the comments and recommendations relative to the
grid voltage parameters. However, in my opinion, there is no data to
support the contention that this is a source of the FX BULK CHARGING
behavior. My reasons for coming to this conclusion are the following:

1.	After a week and a half of careful monitoring, I have not seen
any grid input/output voltage which varies from 123 +1 VAC. 
2.	No. 1 has been the case under all current conditions, ranging
from heavy house load use to sell mode currents as high as 10 aac. 
3.	We have never seen a "STOP SELL" code which indicates over or
under limit VAC.

We have now had over a week of consecutive days of NO SNOW LOAD, that is
to say, the arrays have been clear every morning. We start each morning
with a battery voltage of 25.6 which, as the first sun falls on the
arrays, quickly moves up to the FLOAT level and the new array CC's go
into GT MODE and the systems starts selling. The system sells
consistently depending on cloud cover and stops selling at the end of
the day (sunset). The STOP SELL code at the end of the day is No. 8 or
SAVE COMMAND (per the MATE manual).

Yesterday (Sunday), we generated 31 kWH off the arrays and sold 5 kWH
back to KCE over the 24 hour period. We had a fairly heavy "house load"
yesterday since we pumped the deep well for about 2 hours. This morning,
we started selling at 0815 hours and expect to be selling throughout the
day.

I took the time to go over my daily logs on the system since the "turn
on" in December. The issue associated with the BULK CHARGING CYCLE seems
to always have been associated with heavy snow load and the slow melt
off during the following days. This takes us back to the question that
OutBack seems to have trouble answering: What are the conditions
(parameter values) that FX uses to kick the system into a day long BULK
CHARGING CYCLE? During the times when I experienced this behavior, I saw
STOP SELL CODES of 7,8, and 10. Again we have never seen code No. 3, VAC
over voltage. If we knew this information, we might very well be able to
understand the behavior. 

In summary, I do not think we have a system issue as much as I think we
have a vendor issue (not willing to disclose needed info). I suggest
that I continue to monitor the system on a daily basis and I will let
you know if we experience anything interesting. I do think it is
worthwhile for you to continue to obtain the information relative to the
FX BULK CHARGING criteria from OutBack.

RLJ

on 4/4/10 10:53 PM, Ray Walters at ray at solarray.com
<x-msg://341/ray@solarray.com>  wrote:

Here's something else that would be easy to try, and wouldn't hurt
anything.

R. Walters
ray at solarray.com <x-msg://341/ray@solarray.com> 
Solar Engineer

Begin forwarded message:

From: "Steve Higgins" <shiggins at outbackpower.com
<x-msg://341/shiggins@outbackpower.com> >
Date: April 4, 2010 10:02:43 AM MDT
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org
<x-msg://341/re-wrenches@lists.re-wrenches.org> >
Subject: Re: [RE-wrenches] Outback Grid Problems
Reply-To: RE-wrenches <re-wrenches at lists.re-wrenches.org
<x-msg://341/re-wrenches@lists.re-wrenches.org> >

Not that I'm aware of... We just use it as a quick fix for those
customers with a less than perfect grid connection.   Unfortunately with
some grid connections even this doesn't fix the problem. 

It Open the voltage window from 108 to 132 and frequency to +/- 2 Hz. 

It would be nice to know what the disconnect, or stop sell reason is...
it would give us a better understanding of what is going on.

Steve Higgins. 
Sr Application Engineer. 
Sub-Saharan Africa Business Dev Mgr. 
Outback Power Systems. 
 19009 62nd Ave Ne 
Arlington Wa 98223
360-618-4313

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
<x-msg://341/re-wrenches-bounces@lists.re-wrenches.org>
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of
penobscotsolar at midmaine.com <x-msg://341/penobscotsolar@midmaine.com> 
Sent: Sunday, April 04, 2010 8:26 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Outback Grid Problems

That's a great tip Steve. Is there a downside to changing this setting?

Daryl

Ray,

If you go to the Status FX Sell menu what is the disconnect reason when
it does this?

Also have you set the Grid Tie Authority from IEEE to User, when
customers are all the way out at the end of the line sometimes the grid
isn't as pretty and UL1741 and 1547 require so if the Grid Tie Authority
is IEEE the inverter can disconnect prematurely.  Changing this to User
will open up the disconnect windows a bit so you don't disconnect
prematurely.

Steve Higgins.
Sr Application Engineer.
Sub-Saharan Africa Business Dev Mgr.
Outback Power Systems.
19009 62nd Ave Ne
Arlington Wa 98223
360-618-4313

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
<x-msg://341/re-wrenches-bounces@lists.re-wrenches.org> 
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray
Walters
Sent: Tuesday, March 30, 2010 11:54 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Outback Grid Problems

I considered that there could be something happening due to the grid, as
this guy is way out on the end of the line going into his own utility
transformer.
But then the inverter should show a fault light, and it should try back
again, once the grid voltage drops.
Instead it initiates a full charge cycle and will not connect till the
next day.

R. Walters
ray at solarray.com <x-msg://341/ray@solarray.com> 
Solar Engineer

On Mar 30, 2010, at 10:57 AM, Brian Teitelbaum wrote:

HI Ray,

Have you checked the grid voltage to see if there is variation during

the day which would be enough to kick the inverters out of connection?

Brian Teitelbaum
AEE Solar

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
<x-msg://341/re-wrenches-bounces@lists.re-wrenches.org> 

[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray
Walters

Sent: Tuesday, March 30, 2010 9:43 AM
To: RE-wrenches
Subject: [RE-wrenches] Outback Grid Problems

We currently have a Grid Tie system with a pair of Outback inverters

that are regularly dropping out of sell mode, and letting the arrays
spend all day charging the battery bank.

It seems to do this several times a week, and the customer is losing

substantial production, and gassing the batteries too much.

It will reset itself the next day, or the customer resets it by

turning off the inverters manually.

The system is 24 v, with an old array of 1800 watts running through 2

FM60s, and a new array of 2800 watts running through another pair of
FM60s.

The battery bank is HUP about 4100 Ah @ 24 v (3 strings of 1375 Ah

each) Big battery, I know, but the customer is an electrical engineer,
who wanted maximum storage capacity.

Outback tech support has not resolved the issue, and this has turned

into several service calls, and customer frustration.

We've tried running the controllers through the HUB, and also

independently, and that doesn't make a difference.

I have numerous Outback GT installs dating back to 2003, and have

never had a problem like this.

Any help or advice would as always be greatly appreciated.

Thank you in advance fellow Wrenches,

R. Walters
ray at solarray.com <x-msg://341/ray@solarray.com> 
Solar Engineer

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