Outback MX60 to XW6048 hunting

Brock · January 2009

On our system we have 1000w of solar feeding an Outback MX-60 in turn feeding the battery bank and the XW6048 feeding a sub panel.

This is all in grid tied mode, if the sub panel is consuming all the power there is no problem, the MX-60 puts out a steady say 800w. If the sub panel is only consuming say 400w the XW starts to sell back, or push power back to the main panel where it is used. Anyway at that point the battery voltage starts to bounce where the MX-60 will put out 600w then quickly jump up to 1000w and bounce back and forth and the inverter is also bouncing like this consuming power from the grid and then quickly flipping and selling power back.

I don't know if this is because Outback and the XW don't play well or what. If I had to guess I would say the inverter is starting to sell back, which drops the voltage enough to tell it to stop selling while the charge controller is trying to push that voltage back up. And as soon as the inverter lets up on the selling the voltage starts to rise so the inverter starts to try to sell again and thus the bounce.

It happens every day, it starts really slow, maybe varying 1 volt total and slowing gets worse and worse until the voltage is bouncing about 4 volts in either direction as the inverter is flipping back and forth.

I am not sure it this starts on the charge controller’s sweep, but that has to be confusing the charge controller as well.

If I disconnect from the grid it will even right out, because it can't try to sell or if I add enough loads on the output side of the inverter so it isn't trying to sell (to maintain that voltage). Some days I am not home and it does this all day, the outputs are solid, no lights "bouncing" nothing like that, it just seems odd.

Thoughts?

crewzer · January 2009

Re: Outback MX60 to XW6048 hunting

Brock,

I'll report this to Engineering.

Regards,
Jim / crewzer

BB. · January 2009

Re: Outback MX60 to XW6048 hunting

Brock,

Sounds like an interaction between the XW Inverter and the MX60... (yea--duh... :roll: )

Setting the "charged/finishing voltage" on the MX 60 higher than the sell voltage on the XW may help... The idea being you want the MX to pump 100% of the energy into the "battery" and have the XW behave like a "dump" controller.

The XW should be set low enough for the batteries to reach full charge (14.2 or 13.8 volt "float" like setting?) and the MX set for a 14.2+ volt setting for a "hard charge" to the battery (probably not equalizing though). The idea being the XW manages the state of charge of the battery bank, and the MX 60 prevents damaging overcharging if the XW fails to "regulate" for some reason.

Also, I wonder what the settings for "bulk, absorb, float" overall should be? Perhaps the MX 60 should be configured as a "simple" two stage charger... Bulk for everything, if XW fails then go to Off or "high" float).

Out of curiosity, as I have no inside knowledge of any of this--what you are your MX and XW voltage/charge/sell confuguration settings?

-Bill

Solar Guppy · January 2009

Re: Outback MX60 to XW6048 hunting

Lower you sell voltage on the XW6048, anything above 52V on my system and there is a constant variation on the wattage being sold, this is above the rest voltage of a charged battery bank, but low-enough to have the battery buffer for the XW.

I believe on an XW-6048 to WX-Mppt controller, the Xanbus is used to better coordinate the sell feature

Brock · January 2009

Re: Outback MX60 to XW6048 hunting

I came home for lunch and it was bouncing again so I took a short 8 meg vid of it.

http://www.uwgb.edu/nevermab/inverter.wmv

I will go down and get the settings and then try lowering the sell set point to 52v

BB. · January 2009

Re: Outback MX60 to XW6048 hunting

Solar Guppy wrote: »

I believe on an XW-6048 to WX-Mppt controller, the Xanbus is used to better coordinate the sell feature

I was wondering if that might be true--makes a lot of sense if Xantrex has this feature.

Does the XW Inverter have other charge modes? Bulk, absorb, float, equalize? Or is the Solar Charge Controller + Xanbus supposed to manage these functions? Does the XW have a remote battery temperature sensor???

-Bill

Brock · January 2009

Re: Outback MX60 to XW6048 hunting

Yes I have a remote battery temp on the XW and everything is in a conditioned space, so it rarely varies by more then 10F. When I get home and the array is putting out 200w, I sometimes shut the "sell" off on the inverter and let the Outback do it's thing and go in to absorb.

I bet the Xantrex CC would talk to the inverter much better.

Solar Guppy · January 2009

Re: Outback MX60 to XW6048 hunting

Factory default is set for 54V on the XW-6048, or it was on my unit anyways

My GTFX-3048 has similar needs, I have the sell on that unit @ 51.5V

Its also dependent on the battery bank size, smaller banks need lower sell voltages. Lower your voltage and all should be fine.

Brock · January 2009

Re: Outback MX60 to XW6048 hunting

The Outback MX-60 is set to 57.6 for absorb and 53.8 for float. The sell (grid support voltage) on the inverter was set for 54v I dropped it to 53v and it drastically slowed down the bouncing, probably to about once a second and the sell wattage wasn't as wide as it was. I then lowered the sell voltage to 52 and it slowed to about every three seconds, and stopped "buying" power all together. Now the MX-60 is very stable and the inverter is selling about right, but about every three seconds it jumps and sells about 1.5kw, then drops back to the .5 or so it was at before.

Still seems a bit odd but much better then it was.

Solar Guppy · January 2009

Re: Outback MX60 to XW6048 hunting

Set the sell Value at a compensated Full Charge value for your battery bank. Also make sure the remote sensor is on a stud or on something that reflects the actual battery pack temperature

Also, you may benefit from a firmware upgrade, you can rent to USB-CAN from Xantrex as a kit for 40 bucks and upgrade the inverter ( I just did all my XW equipment. Call the 800 number for info, at the 40 bucks includes shipping both ways

Also on the MX-60, you should probably turn off float and have it set for 2-stage charging, I'm not sure if when its in float mode its ideal for Gridtie sell back, I'm sure Crewzer can fill in some details there

Brock · January 2009

Re: Outback MX60 to XW6048 hunting

Both the Bogart 5050 and the MX-60 are telling me the batteries are at 52.5v, so I feel pretty comfortable with this.

The biggest reason I wanted to trouble shoot this is I plan to add another 500w of panels this summer and I was worried it would make this worse. I was contemplating selling the MX-60 and buy a XW-60. I will give this a shot and see how it goes.

Thanks again everyone, it is amazing how quickly (and easily) this was solved...

BB. · January 2009

Re: Outback MX60 to XW6048 hunting

It may not help, but I would suggest setting float up to 57.6 for float (or turn float off--if possible--opps, SG already suggested this)--while the XW is operating. If the XW fails or is turned off for more than a day or so--then reprogram the MX back to original setting(s).

Try to keep the MX 60 from ever regulating--you want max power always from the array. Configure so that the XW does the regulating as a dump controller.

Again, my two cents. Obviously, I don't know about the re-programming--but it makes sense to check into what changes may have been made to the XW.

-Bill

Brock · January 2009

Re: Outback MX60 to XW6048 hunting

Right, I often glance at the MX-60 to make sure it didn’t somehow get in to float, it never has yet, the inverter has always caught it while trying to push the batteries up. The only reason I hesitate to raise the float is if I forget to turn the “sell” back on while do a battery top off.

I do have the charger on the XW-6048 set to 2-stage charge. At least once a week if it was cloudy or I didn't get to let MX-60 push the batteries in to absorb I will switch the XW-6048 back in to three stage and do a forced charge and let it charge. Usually I can switch off the sell later in the afternoon and let the MX-60 push the batteries in to absorb; I just have to remember to turn on the sell on the inverter later

crewzer · January 2009

Re: Outback MX60 to XW6048 hunting

OutBack charge controllers must be set up a bit differently from their "off grid" configuration when used in grid-interactive applications.

When networked with a Hub, Mate, and an OutBack "G" inverter, the CC must be set to "GT" (grid-tie) mode (see Optimization or Advanced menu, depending on CC model). This allows the inverter to control the CC's charge state and keep it in Absorb mode rather than switch to Float. This increases "Sell" power.

When used with grid-interactive inverter and without networking, leave the CC in non-GT mode, and set the CC's float voltage to the same as the absorb setting.

You may also need to set the inverter's absorb target voltage a bit lower than the CC's setting. And, as Brock has discovered, some of the other settings may need "tweaking".;)

HTH,
Jim / crewzer

Brock · April 2009

Re: Outback MX60 to XW6048 hunting

The thing I have noticed is if I let the batteries go in to float or even in absorb for a while then turn on the sell in hunts a lot more. If I go in to sell mode with the batteries down a bit, even 5 to 10 amps (out of 500) or 1% down it doesn't hunt anywhere near as much. I am guessing this is because the batteries hold the voltage at a more stable lower level, and when they are full the voltage can raise more quickly when either the inverter checks its output or the outback goes in to search mode and starts the swinging.

Outback MX60 to XW6048 hunting

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