How to set my Classic as the master charger with an Outback GVFX

treed678 · November 2013

I'm still waiting on my Outback forum account to be approved but thought someone here might have some ideas.

I'd like the Classic to do 95%+ of the charging, and use the Outback only when my bank needs it and the PV can't produce it.

Right now the inverter charges sometimes from the grid. I can disable that of course with a breaker, but then I can't backfeed. I think I'm also probably "wasting" PV produced power by allowing this.

I assume I'll need a Mate to program the Outback unless there's any other way to set a charging preference for the Classic. Ideas?

Cariboocoot · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

You do need a MATE to program an Outback inverter.

Which inverter do you have?
There really is no charge source preference; if the PV can't provide surplus power to sell back to the grid and the batteries need more power the inverter will provide it. You can limit the charge current from the inverter, but that will also limit the charging from grid when needed.

I think we need more details about your system to see what's going on here.

treed678 · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

It's a Classic 250 (not Lite), GVFX3648, 48V/225ah bank, 2.7kW array. All DIY and just commissioned yesterday.

The subpanel the Outback powers sees very little demand during the day. It seems like(?) the Classic showed 1300 watts today, bank was ~51V, and my meter was spinning backwards, but the Outback was still pulling power from the grid. ?? The Classic showed bulk only I think and I did not see expected higher charge today. Reached 59 & then floated yesterday. (rebulk is set at 52v).

My first concern was that if either charger wasn't aware of the other and working in tandem (like an Outback CC and GVFX would be?), then charge stages might overlap and/or interfere. It seems like that would over or undercharge the bank, shortening its life.

A minimal level of this type of charging interference is probably inevitable without an increasingly controlled master/slave charging arrangement. A solution might be ...say, lower acceptable bank voltages and/or charging frequencies for the "slaved" inverter. Higher requirements, such as greater voltages, could be set for the Classic (master), enabling it to do most or more of the work. The Classic would be the primary manager of the bank.

The second concern was what I described above. The inverter ...with whatever voltage triggers, algorithms, etc are set... might say, "Bank looks low, so time to charge," or just arbitrarily pull from the grid when PV is available. [what I thought I saw today.] I know there is an "RE sell" setting on the Mate/inverter, or a setting anyway *when* to sell.

I'm sure I'm being a little paranoid about it all, but I want to get the most out of the investment. I'd like more control over it and wanted to think twice about whether a $200+ Mate was necessary to potentially just make one change (disable charging or 1-2 other settings). Guess I need to get one.

Blackcherry04 · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

When you set the GVFX to " Grid " input that will activate the charge settings for the Inverter to use the " Re-float " set voltage and timer. This way the charger will only activate when the voltage drops below the Re-float setting. When it set to "Gen" It'll show 24 hrs on the timer.

I think It's default is Gen and you have to have a Mate to change it. The " Sell " is turned off when in "Gen " input.

I don't use this, but it's also a Grid Item. It works with the charger Off and allows you to maximize your PV production.

Attachment not found.

.

treed678 · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

Excellent. Just the kind of info what I was looking for. Thank you, sir or madam.

I should have just bought a MATE to start with. I can never leave anything "as is."

Always have to mess with stuff. I'm sure NONE of you have that problem though, do you? haha.

boB · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

In addition, one thing to do for selling to the grid during the day is to make sure that the Classic's charge voltage (Absorb and Float)
is always a couple volts above the GFX's sell voltage. This will ensure that the PV is always pulling up on the battery voltage
while the GT inverter is pulling that voltage down. Sort of a tug of war I call it.

Keeping the Classic's battery charge voltage a bit higher than the inverter's charge voltage setting will ensure that the Classic
won't be overtaken by the inverter's charging from the grid. i.e. If the charger is charging the battery at or above the
Classic's voltage setting, then why should the Classic do any charging ? The inverter is doing all the work (maybe).
That's another way to look at it.

boB

treed678 · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

Roger that, boB.

That was basically my thinking. The inverter is now dictating, or at least limiting the bank voltage, output/input, etc and not allowing the Classic to keep the bank voltages up where I'd like them. My MATE is on the way though, so I'll be able to fine tune the "tug of war" soon. The only way to "beat" the inverter right now would be to supply more than it can distribute [to the grid **AND** to AC circuits], which would be a LOT of PV/CC, and completely unnecessary.

I remember reading that the Outback has fairly low parameters (~52V I believe) for resell, float, etc, so without a MATE, I don't believe the Outback will not allow the bank to stay above 52V unless... 1. Backfeed breaker is OFF, and/or... 2. Inverter out (subpanel) is also OFF **OR** the Classic/PV input is adding more power than - a. can go to the grid, b. the subpanel circuits pull. Otherwise the inverter always wins the tug of war.

mtdoc · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

If you are selling to the grid - i would strongly recommend that in addtion to a Mate, you invest in a Hub4 and an Outback FlexNet DC. This will allow you to base your selling on end amps (aka return amps). This is what I do based on a similar system (see my sig). You want it set up so that the Midnite Classic is harvesting maximum PV and the GVFX is selling it to the grid and all being done while keeping you batteries in the best shape possible for a long lifetime. Setting this up optimally on the Outback equipment is a bit convoluted and it took me a bit of time to figure it out. If you get this equipment, I can walk you through it.

boB · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

treed678 wrote: »

I remember reading that the Outback has fairly low parameters (~52V I believe) for resell, float, etc,

Right ! That voltage, 52 volts or so is chosen because it is above the batteries' resting voltage but not
too high... Keeping the battery voltage too high all the time, like getting it up to absorb and even
float somewhat every single day wastes energy and turns out is not all that great for the longevity
of the batteries. You DO want to give the batteries a good absorb cycle once every week or two.
I cannot remember if the GFX does that or not. It should do a full charge after a line outage
though but that does not happen often enough to keep the batteries in good shape (non-sulfated).

boB

mtdoc · November 2013

Re: How to set my Classic as the master charger with an Outback GVFX

boB wrote: »

You DO want to give the batteries a good absorb cycle once every week or two.
I cannot remember if the GFX does that or not. It should do a full charge after a line outage
though but that does not happen often enough to keep the batteries in good shape (non-sulfated).

boB

Exactly - and that is what using the FlexNet DC allows you to do. You set it up so that it only sells after "Charge parameters are met" which means end amps are below a set threshold and battery voltage is above a set threshold for a set amount of time. You can set it up so that once a day the GVFX will do a short absorb and check those parameters before allowing continued selling to the grid.

How to set my Classic as the master charger with an Outback GVFX

Comments

Categories