Xantrex XW6048 - fault F49 - DC over voltage

RCinFLA · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

dlenox,

The graphs are absolutely horrible. (graphs are good, performance is bad).

What is your maximum charge amp setting, bulk voltage setting and how many A-hrs are your batteries.

The inverter goes into bulk charging after an outage of more then few seconds but 66 vdc would be extremely high number.

Can you say more about details of discussion of this '20 second stabilization' period? Sure sounds like a XW issue.

Since you guys are using solar charging, I wonder if things would improve if you limit the XW inverters maximum charge current setting to a low value. I do this on by old SW inverters primarily because they are used for UPS and there is no need to push the batteries hard on recharge current.

BB. · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

I am also curious about the maximum rates of charge (both for the inverter and the solar panels)...

Your battery bank seems small at 258 AH (@48 volts). If the XW inverter + charge controller decided to dump maximum charge rates into the bank--that would seem to drive the voltage high quickly.

As batteries age, they can change their behavior... I wonder if their peak voltage rises over time (with same peak charging current used)?

-Bill

Solar Guppy · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

Glad to hear lowering the sell voltage corrected your issue

Technically, if you keep AGM's fully charged, which you were doing with your 59v sell voltage, the AGM's have no ability to then present a load to the XW. All chargers to some degree are designed to have the battery bank stablize things ... in your case with fully charged agms and a battery bank that is to small, it doesn't take much energy to quickly raise the battery banks voltage.

You have been informed by the manufacture the battery bank is to small, which it is . so your choice is to install battery's that are correct for a 6kW inverter and or lower the sell voltage, either of which will eliminate your fault.

Not really sure what other options you would expect?

pcguy2u · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

Solar Guppy wrote: »

Glad to hear lowering the sell voltage corrected your issue

Technically, if you keep AGM's fully charged, which you were doing with your 59v sell voltage, the AGM's have no ability to then present a load to the XW. All chargers to some degree are designed to have the battery bank stablize things ... in your case with fully charged agms and a battery bank that is to small, it doesn't take much energy to quickly raise the battery banks voltage.

You have been informed by the manufacture the battery bank is to small, which it is . so your choice is to install battery's that are correct for a 6kW inverter and or lower the sell voltage, either of which will eliminate your fault.

Not really sure what other options you would expect?

As I said in my intended post to Xantrex above - the cause and effect are terribly unclear and there is no way to answer all the open questions at the moment, including whether or not the size of the battery bank is too small. At least not until Xantrex looks at this situation with an intent to get to the bottom of the issue - and only then, if they come clean.....................

RCinFLA · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

From Xantrex XW installation manual, page 2-9.

"Important: The minimum recommended battery bank is 100 Ah. The inverter is designed to operate with batteries and should not be operated without them."

At 259 A-hrs he meets these published requirements.

BB. · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

I assume that the XW Inverter has a way of limiting the maximum AC Mains supplied charging current (either directly as XX amps, or indirectly by programing C/20 battery capacity).

It would be interesting if the XW Inverter + the XW MPPT Charge Controller coordinated so that the total power supplied to charging the battery is <XX Amps. (for the case, AC Mains Power Glitch in middle of a sunny day... AC Mains comeback and the Inverter starts trying to charge the batteries while the Solar Charger is also charging (and during that time that we have the 5 minute timeout because of the previous AC mains failure before the GT Sell Mode can kick back in).

I assume that the XW MPPT Solar Charge Controller will stop providing charge current if battery voltage exceeds XX Volts--perhaps it has some "filtering" that prevents it from cutting off charge current too quickly and both are providing full rated charging current to the poor battery bank at the same time--even though battery voltage is going "through the roof".

It does sound like we have a "systems issue" here. If neither of the charge controllers is limiting the battery voltage per programmed settings (or not limiting quick enough)--that is not good (capt. obvious here :roll:).

-Bill

Solar Guppy · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

Yes, Marketing won on that one ... From the director of Engineering it was 400ah for the XW-6048 doing full rated gridtie selling. I know this first hand as I was on the development team.

Lets see 100ah is a 20 hour rate so 5 ah ( 100 / 20 ) so 5ah * 50V is 250 watt/hr , the battery's are not linear, start pulling higher C rates and things are measured in minutes not hours for that recommend minimum

As I said, I'm pleased we helped the OP, lowering the sell voltage solved his issue.

pcguy2u · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

Solar Guppy wrote: »

Yes, Marketing won on that one ... From the director of Engineering it was 400ah for the XW-6048 doing full rated gridtie selling. I know this first hand as I was on the development team.

Lets see 100ah is a 20 hour rate so 5 ah ( 100 / 20 ) so 5ah * 50V is 250 watt/hr , the battery's are not linear, start pulling higher C rates and things are measured in minutes not hours for that recommend minimum

As I said, I'm pleased we helped the OP, lowering the sell voltage solved his issue.

As I said, I don't know if the issue is solved or we're just not seeing the problem. The reason being is that the problem doesn't occur on a regular basis - can be months between onsets.

And even if the settings cure the problem, that is, it never occurs again, it is very likely that the underlying issues, the one that causes the onset and the one that causes the subsequent infinite loop for weeks at a time, are a system programming problem.

RCinFLA · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

On a grid sell, the battery should only be acting as a short term capacitor.

There has to be a hysterisis on battery sell voltage to avoid thrashing sell activation but a 20 second period seems very long. A 5000 watt solar supply could push a lot of current at the battery and raise it quite a bit in 20 seconds. But the solar charge controller should limit the battery charge voltage in that case.

Can the XW solar controller operate independently without Xanbus connection to XW inverter? What exactly does XW inverter communicate to solar controller (like remove its battery voltage regulation because XW inverter is selling and managing battery voltage)?

Just seems like something is loosing control if so much power is momentarily being pushed to a fully charged battery. I still think it relates to the grid impedance checking.

dlenox · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

RC,

RCinFLA wrote: »

dlenox,

The graphs are absolutely horrible. (graphs are good, performance is bad).

Can you say more about details of discussion of this '20 second stabilization' period? Sure sounds like a XW issue.

Like I said it was overcast rainy day, one of those days where you are lucky just to keep batteries charged.

According to Xantrex, once the battery voltage goes above the sell point, it has to stay there for 20 seconds before the inverter will go into sell mode. They referred to this as a "stabilization period".

Dan Lenox

dlenox · November 2009

Re: Xantrex XW6048 - fault F49 - DC over voltage

PcGuy,

I put up a posting on the Xantrex discussion board
<removed link as the site is perma-dead>

You may want to peruse there to see if you can get any help.

Dan Lenox

pcguy2u · March 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Ok - the saga continues on this Fault 49 problem. All has been perfect since mid-September 09, then:

3/10/10 - 1:50PM - Sunny/windy/50 degrees - Fault 49 (DC overvoltage) occurred 6 times in 12 minutes and then stopped cycling with F49 displayed. Immediately turned off the main breaker (grid disconnect) and turned it back on immediately. Went back to the inverter - F49 still displayed. Pressed (without holding) the power/reset button on the front of the inverter and the unit began to sell correctly without further incident.

3/16/10 - 9:23AM - Sunny with very slight haze/59 degrees - Fault 49 (DC overvoltage) occurred 3 times in 2 minutes and then stopped cycling with F49 displayed. This time I did not touch the main disconnect, but only pressed (without holding) the power/reset button on the front of the inverter - began to sell immediately and within 3 minutes, the inverter started to display a drop in the Sell watts incrementally while making a whining sound I have never heard before. Just before reaching zero on the display, Fault 49 (DC overvoltage) appeared. I immediately pressed and held the power/reset button on the front of the inverter. The unit then displayed "OFF" and I immediately pressed and held the power/reset button on the front of the inverter and the inverter started a 5 minute countdown. At the end of the countdown, it was necessary to change the SCP so that the "Advance Settings" could be accessed and to then set "SELL" to "ON". These two changes must have been reset as part of the power off sequence - they are normally set to "Advanced" and "ON" on this system.

BTW, the system was generating between 3000 and 5000 watts this morning.

The above incidents suggest that previous assumptions about changes made to the inverter settings are not valid. Those changed settings include turning off the AC charger and reducing the DC sell voltage to 52.8 volts and appear to not avoid the onset of F49 Cycling.

Also, a previously made assumption may still be valid - that being that turning off the grid connection which may play a part in resetting the inverter so that it acts normally once again.

The next time this kind of incident occurs, I will turn off the grid breaker, turn it back on immediately and then momentarily press the power/reset button on the front of the inverter. Should that cure the cycling problem and bring the unit back to normal duty, that will reinforce the thought that that method is good for the interim/long term.

What none of this answers is the question of what initiates the Fault 49. Some time back in this thread, I suggested that I would allow the cycling of the F49 to continue while I tested the voltage level of each battery individually - unfortunately that thought did not occur until the system was running again. I will try to remember to do that next time.

Many thanks to all who have contributed to this thread.

Nick

Solar Guppy · March 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Your battery bank is to small ... Xantrex told you this as have members here. The 40 seconds the XW stops selling with the large variable irradiance, you battery's have no place to put energy ( fully charged ), the voltage raises and faults out. My 660 amp bank and even with 8kw to the batterys has never had this fault, I have seen the condition in variable conditions that the unit stops selling and the battery voltage ramps up slowly, but the highest I have ever seen is about 59V. ( This only happens when the XW's charger is enabled ) and your gridtie selling solar from charge controllers.

Not quite sure what state the inverter is in for those seconds its getting ready to restart sell, but it is sending some energy into the battery's and it appears its unregulated.

Regardless, if the manufacture tells you you need to make a change and ignore it, not sure what help you would expect from them, from there prospective its working as designed

sub3marathonman · March 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

pcguy2u wrote: »

Ok - the saga continues on this Fault 49 problem. All has been perfect since mid-September 09, then:

BTW, the system was generating between 3000 and 5000 watts this morning.

Nick

It was so subtle that I almost didn't catch it. But I have never seen my XW6048 going at 5000 watts. So I looked at Nick's setup. "32 KC 200's totaling 5000w (after deducting efficiency factor) of PV." I wasn't 100% sure what the KC was, but I guessed Kyocera KC200GT. So with the XW6048 sizing tool, it comes up with the alternative of 3 panels/string or 4 panels/string. Both have a maximum recommended 6 strings. So an absolute maximum of 24 panels. But Nick has 32. So if I am correct that it is KC200GT panels, there are too many for the XW6048. And then add in the small battery bank too.

OK, after a bit more research, the sizing tool was talking about the charge controller maximum. Since there are two charge controllers, I suppose you could be OK with 32 panels total for the XW6048. Set up as 4 panels/string, and 4 strings for each charge controller. But it still seems like a lot of panels for the XW6048.

Even more research. The CEC Power rating of the XW6048 is 5752W. So the CEC Power rating = PTC Rating * Number of panels. If it is KC200GT, that is 5622.4W, which is pretty close to the 5752W maximum. But if it is KC200GX-LPU that would be 5776W, which would be over the 5752W maximum.

aj164 · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

The same fault happened to one of our systems today. I have not been out to see the inverter yet in person, but I was told it read F49, and it had shut down - leaving all the backed-up circuits without power.

1) Why didn't the inverter at least switch its relay to allow AC pass-through (keeping the backed-up circuits going)? This is important because there are refrigerators and freezers on this panel.

2) All of the literature for this inverter says the minimum required battery bank is 100A-H. We have 105A-H on this system because the customer didn't want a large investment in batteries at this time (He's waiting for new technology). I have read this thread and seen the recommended 400A-H minimum. However, 400A-H is _not_ in the manuals. If it had been, I would have told the customer he had to buy at least 400A-H capacity.

The setup is:
XW4548 inverter
XW C60 MPPT charge controller
4 DEKA 105A-H AGM batteries (series 48V)
16 BP190 190W PV modules, wired 4 strings of 4

Thanks,
AJB

Brock · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

I think the inverter cannot sell all the solar power being generated and the CC pushed it all in to the batteries, which in turn likely cooked them.

I am not sure what you have the CC bulk voltage set to. I have mine at 57.6 and sell on the inverter at 52. I found once you get above that sell voltage with my smaller bank (about 500 amps at 48v) the battery voltage will bounce and spike when the MX-60 is sweeping. Although the highest I have ever seen the bank was 59.1v according to the Bogart.

If the batteries are sitting lower at the 52 they can absorb some of the spike and even out the bouncing, but if they are sitting at 57 they are completely topped off. This would also be the case if you had 5200w of solar and selling 5000w with 200w being pushed in to the batteries.

As to why the inverter behaves the way it does, I can't help that is a programming issue. I do know cycling the AC power seems to reset the inverter. Also cycling grid power to the inverter will consume some of the power allowing the voltage to stay a bit lower on the bank until it is full again.

Bottom line the inverter can't "sell" all the solar power it's generating and it is pushing your batteries up to high, a larger battery bank won’t fix this. You need to lower the solar input to be below the inverters max selling or somehow increase the sell output with an additional inverter or some DC load or something.

ggunn · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Brock wrote: »

I think the inverter cannot sell all the solar power being generated and the CC pushed it all in to the batteries, which in turn likely cooked them.

What could cause that to happen? Larger capacity charge controller than inverter? The grid is pretty much an infinite sink, isn't it?

mike95490 · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

ggunn wrote: »

The grid is pretty much an infinite sink, isn't it?

No, my wife believes the Web is the infinite sink, followed closely by the TV

Brock · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

ggun, if the solar array is maxing out at say 6500w in full sun at solar noon, the XW6048 can only invert 6000w (actually only about 5800 watts) and push it out to the grid, the remaining 500w will bulk charge the battery bank. So the inverter itself is the limiting factor.

aj164 · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Brock wrote: »

ggun, if the solar array is maxing out at say 6500w in full sun at solar noon, the XW6048 can only invert 6000w (actually only about 5800 watts) and push it out to the grid, the remaining 500w will bulk charge the battery bank. So the inverter itself is the limiting factor.

When the inverter is not selling (sell turned off), the charge controller will limit its output if the batteries can't take the full output. Why would it not be able to limit its output in a similar fashion in sell mode when the inverter can't handle full power?

When in off-grid mode and light loads on the invertr, the charge controllers back off to just a trickle. Turn on a big load, such as the A/C, and the charge controllers quickly throttle up to 3kW (for example). As soon as the A/C goes off, the chargers are back at a trickle.

Brock · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

You absolutely correct the charge controllers will limit the power going in to the batteries. The odd thing, which normally isn't an issue with MX-60 is when they do their sweep they don't limit their output. So if a battery bank is totally full for a couple of seconds it can receive a lot of power from the array. My guess is in this case the charge controllers bulk are pretty high, potentially damaging the batteries, and then when that sweep happens there is no capacity left in the batteries to absorb the power and they get pushed up above the 64v cutout on the XW inverter.

aj164 · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Brock wrote: »

You absolutely correct the charge controllers will limit the power going in to the batteries. The odd thing, which normally isn't an issue with MX-60 is when they do their sweep they don't limit their output. So if a battery bank is totally full for a couple of seconds it can receive a lot of power from the array. My guess is in this case the charge controllers bulk are pretty high, potentially damaging the batteries, and then when that sweep happens there is no capacity left in the batteries to absorb the power and they get pushed up above the 64v cutout on the XW inverter.

Seems like the firmware logic needs to be improved.

Dave Angelini · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

mike90045 wrote: »

No, my wife believes the Web is the infinite sink, followed closely by the TV

She is definately correct!

ggunn · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Brock wrote: »

ggun, if the solar array is maxing out at say 6500w in full sun at solar noon, the XW6048 can only invert 6000w (actually only about 5800 watts) and push it out to the grid, the remaining 500w will bulk charge the battery bank. So the inverter itself is the limiting factor.

Makes sense, thanks. One obviously needs to pay attention to inverter capacity when sizing the array.

aj164 · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

ggunn wrote: »

Makes sense, thanks. One obviously needs to pay attention to inverter capacity when sizing the array.

It doesn't really make sense to me. From a programming perspective, why not have the charge controller throttle back before the voltage climbs to a fault condition? It is clearly quite capable of throttling its output regardless of input capacity.

Brock · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Normally it wouldn't be an issue because if the battery bank is healthy or sized to match the array, the array could never push the battery bank up that far.

Having said that, you would have thought from a programming perspective they would have considered this might happen and account for it. Solar Guppy might know if they have accounted for this in newer software or the FM-60 or FM-80 designs.

To be honest I don't know if any of the other charge controllers behave the same way or not.

ggunn · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

Brock wrote: »

Normally it wouldn't be an issue because if the battery bank is healthy or sized to match the array, the array could never push the battery bank up that far.

Having said that, you would have thought from a programming perspective they would have considered this might happen and account for it. Solar Guppy might know if they have accounted for this in newer software or the FM-60 or FM-80 designs.

To be honest I don't know if any of the other charge controllers behave the same way or not.

Can't all this be avoided by sizing the array appropriately to fit the inverter? It seems to me that if the array is oversized for the inverter, no matter how large the battery bank is, there is the possibility of the batteries being fully charged and the array producing more energy than the inverter can distribute to the AC loads and/or grid.

sub3marathonman · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

aj164 wrote: »

2) All of the literature for this inverter says the minimum required battery bank is 100A-H. We have 105A-H on this system because the customer didn't want a large investment in batteries at this time (He's waiting for new technology). I have read this thread and seen the recommended 400A-H minimum. However, 400A-H is _not_ in the manuals. If it had been, I would have told the customer he had to buy at least 400A-H capacity.

AJB

OK, I guess I'm not the only one who reads the literature. And yes, that is exactly what it says. But for the advice of Solar Guppy, I would have been in a very similar dilemma.

From what I've been able to deduce, the XW6048 has a range of operation. At a minimum, it needs a 100 ah 48v battery bank. This minimum occurs with the minimum number of panels the XW6048 will work with. As the number of solar panels goes up, the battery bank must go up too. So a sliding scale. With mine, I'm not near the maximum of the inverter, so I'm OK, but really close to the minimum amount of batteries for my setup, with the 357 ah bank. If I pushed the XW6048 further with more panels, it wouldn't work correctly.

What I never can really understand is how the inverter sells power. The PV panels supply current to the charge controller. The charge controller supplies current to the batteries, which are also hooked up to the inverter. So I just can't see if the current is converted into stored battery energy and then reconverted almost simultaneously into electricity for the XW6048 to sell. I thought it would be like an ice rink, that the electricity would just "skate" over the storage battery and essentially go directly to the inverter.

It may be worthwhile to look into lithium batteries, although currently there is turmoil in their world with one of the suppliers.

Brock · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

ggunn wrote: »

Can't all this be avoided by sizing the array appropriately to fit the inverter? It seems to me that if the array is oversized for the inverter, no matter how large the battery bank is, there is the possibility of the batteries being fully charged and the array producing more energy than the inverter can distribute to the AC loads and/or grid.

Yes, and yes

I can relate to the reason for slightly over sizing the solar array. I might do this because 5% of the year the array might actually exceed the inverters output capability and then the charge controllers might throttle back on their output, which leads to some unused power. But for 95% of the time the array would be below the inverter capabilities and you would be getting the most out of the panels, charge controllers and inverter. As long as you understand that going in you should be fine.

They way I think of batteries used in a grid tie situation like this is the battery are like the reservoir behind a dam and the inverter is like the turbine generating electricity. If you have a 4 foot dam the water will quickly fill the reservoir and run out the spillway, where as if you have a larger dam it can collect more water and when a downpour does happen it can cope with those surges much better than a smaller dam would. I hope I didn't confuse too many people with my dam analogy.

BB. · April 2010

Re: Xantrex XW6048 - fault F49 - DC over voltage

I guess it all comes down to timing... There appears to be time constants of seconds to 30 seconds on the XW GT inverter as it ramps up to sell power... If the battery voltage rises quickly to greater than Vfault in less than 30 seconds, the inverter will fault before it can actually begin selling power.

And, it sounds like (although I am less sure of this point from my reading/memory so far) that Solar Charge Controller may not respond quickly either---I would hope that no matter how large the array vs battery bank sizing--that the Solar Charge Controller would simply see Vbatt>Vabsorb and immediately cut back on energy transfer to the battery bank.... Possibly this is not happening... Either it is programmed to ignore XX seconds of Vbatt>Vprogrammed--and / or once in a while the MPPT controller tries to dump 100% of the array power to the battery bank while finding the MPPT Vmp/Imp operating points. And it is possible that the battery voltage/current is unregulated during parts of these cycles...

In any case, we now have a very large solar array and a relatively small battery bank. The GT Inverter is programmed to respond "gently/slowly" to changes in available power (sell voltage) and the Charge Controller is, at times, capable of dumping high amounts of power to the battery bank.

The "small battery bank", if fully charged, does not have the "buffering ability" to hold the bank voltage within a valid range when everything is plugged in together...

IIRC, the original recommendations were either 400 AH or 600 AH battery bank minimum (at 48 VDC) to support a XW 6kW inverter properly. And I would assume that this is a 6+ kW array and a 6kW GT inverter.

If this were a smaller solar array on a smaller battery bank (say 100 AH and a 1 kW array)---the voltage excursions may not be an issue.

Looking at the maximum current from a 6kW inverter (XW is rated to 12 kW surge--no small number):

6,000 watts * 1/0.85 eff * 1/42 volts = 168 amps maximum

If you assume that you never want to run a standard flooded cell storage battery at a continuous load of C/2.5--then the size of battery bank required to support a 6,000 watt inverter (or solar array):

168 amps * 2.5 rating = 420 AH @ 48 volt battery bank

So, a battery bank rated at 400-600 AH would seem to be an "optimum" minimum rating if the system is expected to run 6kW loads/charging currents.

Anyway--that I how I have been understanding the issue.

I am sure I have missed something--so sorry in advance. :roll:;)

-Bill

Xantrex XW6048 - fault F49 - DC over voltage

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