Help setting up Xantrex XW4548 x 2 system

neo2299

Hey guys...I've called xantrex several times and get different answers each call....Here is my setup:

45 x Canadian Solar 240w panels (10.8kw)
4 MPPT 60-150 Controllers
2 XW4548 Inverters
24 Decca Dominator gel 180ah Batteries (3 strings of 8 )

I have it grid tied and net metered....I would like it to keep the batteries fully charged and than sell to the grid. Xantrex told me to set grid sell voltage to 64v. My float is around 54v, max charge at 56v....anything higher and the batteries start to bubble/boil....I have a 10.8kw system and in perfect conditions it's only generating 6.4kw which seems way too low....Any advice on the settings? 2state no float? 3 stage? voltage?

Thanks in advance.

Cariboocoot

Re: Help setting up Xantrex XW4548 x 2 system

Some random observations and comments:

You have 10.8 kW of panel, but you have 9 kW of inverter. Output will not exceed inverter capacity. The panels themselves will probably average about 8 kW so it's all good.

I take it the four charge controllers was something to do with panel placement? Forty-five panels capable of about 173 Amps would normally be on three 60 Amp controllers. Not a big issue; running them at lower capacity can be good, especially on a GT system (where they'd run 'flat out' whenever power is available 'cause it all goes to the grid).

They told you 64 Volts for SELL? That would boil FLA's and probably cause your gel batteries to explode.

Do you have any specific charge specs for those batteries? SELL Voltage would be based on the battery Voltage recommendation, not some arbitrary number from Xantrex.

neo2299

Re: Help setting up Xantrex XW4548 x 2 system

Battery says float at 6.7 - 6.8v each and max charge at 7.3v. We have 2 different roofs (1 hour, 1 garage) so we have 12 panels on each x3 controllers and 9panels on the 4th controller. I'm just confused because when I turned on the system for at test run I would get 7.5+kw and now that i've gone through the settings with xantrex it seems to be maxed out at 6.4kw

BB.

Re: Help setting up Xantrex XW4548 x 2 system

There is some setting for "automatic sell voltage control" where the programmed sell voltage is not the "real" sell voltage--You need to read the manual (for your firmware) closely.

-Bill

NorthGuy

Re: Help setting up Xantrex XW4548 x 2 system

64V is a trick setting for so called "Enhanced Interactive Mode". It is on page 3-25 of your manual. It is supposed to move batteries through absorb stage every day while selling the excess.

If you don't cycle the batteries, you probably do not need daily absorptions, and it is better to set selling volts just below (0.5 to 1.0V less) the float volage set on SCCs.

Cariboocoot

Re: Help setting up Xantrex XW4548 x 2 system

One problem you have (which you won't like hearing) is insufficient battery capacity. Xantrex specifically recommends a minimum of 100 Amp hours capacity per 1kW of inverter on 48 Volt systems. So by rights you should have 900 Amp hours, not 540. This is a matter of filtering the AC ripple, and could be a problem in your case.

If the SELL Voltage is set too high then part of your power output is lost to pushing the Voltage up to that point.

If you were getting 7.5 kW @ 54 VDC that's about 138 Amps from the panels, so obviously 34 Amps has "gone missing" but with arrays facing in different directions that is not unexpected. What settings did you change that cause production to drop by a further 1 kW? Sell Voltage up?

I would lower it to 54.4 and see how the system behaves. And resign yourself to the idea of having to replace those batteries sooner rather than later.

Some of the forum members who run Xantrex GT systems will have better insight on this I'm sure.

neo2299

Re: Help setting up Xantrex XW4548 x 2 system

I'm not sure why it's not generating a tad more power....I'm so confused on these settings and which ones to do....I just want to sell to the grid and keep the batteries fully charged so they last longer....Not sure if I should set 2stage or 3stage....not sure if I should have the inverter charge the batteries at night....dont get me wrong, i'm happy producing 6kw of power, but I would really like to make sure I have this setup correctly so I can just leave it alone and let it work.

Attachment not found.Attachment not found.

Cariboocoot

Re: Help setting up Xantrex XW4548 x 2 system

The inverters should not need to charge the batteries at night as they aren't being cycled.

NorthGuy

Re: Help setting up Xantrex XW4548 x 2 system

neo2299 wrote: »

I'm not sure why it's not generating a tad more power....I'm so confused on these settings and which ones to do....

The settings you're discussing do not affect the power. You need to look at each of the charge controllers separately (press down arrow twice an each SCC to see how much power this particular SCC is producing). You need to know how many panels are attached to each, what is the orientation and angles on these panels. You need to know the temperature outside. Then you look at these numbers and see if the production is reasonable for the conditions.

Have you installed everything by yourself or did you have an installer?

neo2299 wrote: »

I just want to sell to the grid and keep the batteries fully charged so they last longer....Not sure if I should set 2stage or 3stage....

You need 3-stage for solar chargers and 2-stage for XW4548 (which only will turn on after an outage).

neo2299 wrote: »

not sure if I should have the inverter charge the batteries at night....

No.

mike95490

Re: Help setting up Xantrex XW4548 x 2 system

GEL batteries, or AGM ? Gel batteries are often used in UPS and high surge current applications, but not generally suitable for deep cycle usage (useable for maybe a 100 cycles or less). GEL also does not handle high charge current well.


AGM do come with deep cycle ratings, and do well with high amperage charge and discharge.

neo2299

Re: Help setting up Xantrex XW4548 x 2 system

mike95490 wrote: »

GEL batteries, or AGM ? Gel batteries are often used in UPS and high surge current applications, but not generally suitable for deep cycle usage (useable for maybe a 100 cycles or less). GEL also does not handle high charge current well.


AGM do come with deep cycle ratings, and do well with high amperage charge and discharge.

These are Deka Dominator Gel 6v batteries.

neo2299

Re: Help setting up Xantrex XW4548 x 2 system

neo2299 wrote: »

These are Deka Dominator Gel 6v batteries.

Just thought i'd give a little update....I think i've partially figured out the issues. I have the charge controller set to custom battery type. When I raise the float voltage from 54v to 57v my power goes from 6.4kw to almost 6.8kw during the test at 12:30pm. My batteries test out in the 6.7-6.8 range for the most part, but I have 3 batteries that are always higher...7.0 to 7.4v. When I raise my voltage up those 3 batteries seems to be the ones that start the bubbling sound first. I think the default voltage is around 58v float on the controllers which is probably why I was getting 7kw+ while I tested them a couple weeks back. My south facing slope has two different arrays....Array 1 has 9 panels and Array 2 has 12 panels. When I look at the stats for those I see that they produce almost the exact same amount of power during the day. They're both around 1.65kw. That tells me that some where my charge controllers are limiting the amount of power. I just wish I could figure out how to let these things go full power without screwing up the batteries.

Thanks

Cariboocoot

Re: Help setting up Xantrex XW4548 x 2 system

Um, gel batteries shouldn't make any bubbling noises.

The only way you're going to get 'full performance' from this system is to change the battery bank to a larger capacity one made of flooded cells (or AGM's).

NorthGuy

Re: Help setting up Xantrex XW4548 x 2 system

neo2299 wrote: »

Just thought i'd give a little update....I think i've partially figured out the issues. I have the charge controller set to custom battery type. When I raise the float voltage from 54v to 57v my power goes from 6.4kw to almost 6.8kw during the test at 12:30pm. My batteries test out in the 6.7-6.8 range for the most part, but I have 3 batteries that are always higher...7.0 to 7.4v. When I raise my voltage up those 3 batteries seems to be the ones that start the bubbling sound first. I think the default voltage is around 58v float on the controllers which is probably why I was getting 7kw+ while I tested them a couple weeks back. My south facing slope has two different arrays....Array 1 has 9 panels and Array 2 has 12 panels. When I look at the stats for those I see that they produce almost the exact same amount of power during the day. They're both around 1.65kw. That tells me that some where my charge controllers are limiting the amount of power. I just wish I could figure out how to let these things go full power without screwing up the batteries.

The power you get is not supposed to go into batteries, which are already full, but is supposed to be sold to the grid. Batteries are best kept at float voltage (usually 52-54V). You set sell voltage a tad less than this, say 0.5 to 1V less, to ensure that it does sell the power. If it doesn't sell, it won' produce it.

Full batteries cannot accept any power. If you try to put all the power into batteris by ramping up voltages, you most likely will fry them.

YehoshuaAgapao

Re: Help setting up Xantrex XW4548 x 2 system

neo2299 wrote: »

I'm not sure why it's not generating a tad more power....I'm so confused on these settings and which ones to do....I just want to sell to the grid and keep the batteries fully charged so they last longer....Not sure if I should set 2stage or 3stage....not sure if I should have the inverter charge the batteries at night....dont get me wrong, i'm happy producing 6kw of power, but I would really like to make sure I have this setup correctly so I can just leave it alone and let it work.

Attachment not found.Attachment not found.

3-stage

Use enhanced interactive mode. That is activated by setting grid support voltage to equal the equalization voltage. You need this to get proper absorption charge while selling to the grid.

Turn off anything related to equalization on Gel (or AGM) batteries.

You should lookup specific charge voltages from your battery manual. Gel batteries are picky. Excessive charge/float voltage is particularly destructive to gel batteries.

My charge controllers usually starts a new charge cycle every morning regardless of voltage. The inverter usually don't do a charge cycle during the night. If you want to be sure the charge controllers do all the charging except when the batteries are really low, lower the ReCharge volts to 46-48V on the inverter but don't change that on the charge controllers (default of 50V seems fine).

neo2299

Re: Help setting up Xantrex XW4548 x 2 system

Thanks for the advice on the battery settings....

So...After church today I come home and notice 1 of my 4 charge controllers isnt producing anything...It has the correct voltage coming into it, but just shows 0 watts. I've reset/restarted it, but nothing. It turns right on and shows 99volts, but 0 watts....I've had that happen before, but usually a quick restart takes care of the issue.

Any ideas?

NorthGuy

Re: Help setting up Xantrex XW4548 x 2 system

neo2299 wrote: »

Thanks for the advice on the battery settings....

So...After church today I come home and notice 1 of my 4 charge controllers isnt producing anything...It has the correct voltage coming into it, but just shows 0 watts. I've reset/restarted it, but nothing. It turns right on and shows 99volts, but 0 watts....I've had that happen before, but usually a quick restart takes care of the issue.

Any ideas?

Most likely, not producing becuase there's no place where the energy would go.

Cariboocoot

Re: Help setting up Xantrex XW4548 x 2 system

NorthGuy wrote: »

Most likely, not producing becuase there's no place where the energy would go.

Yes. The easy test here is to disconnect whichever controller is making the most current and see if the one with zero output springs to life. If it doesn't, something is wrong.

neo2299

Re: Help setting up Xantrex XW4548 x 2 system

Cariboocoot wrote: »

Yes. The easy test here is to disconnect whichever controller is making the most current and see if the one with zero output springs to life. If it doesn't, something is wrong.

The charge controller hadn't been screwed down yet so it was leaning....Once I straitened it out and screwed it down everything worked great.....

I talked to a schnieder tech guy and we did a hard reset through the CC menu directly....Now everything works great! 8.3kw+....he wasnst sure why it was stopped at 6kw before.

NorthGuy

Re: Help setting up Xantrex XW4548 x 2 system

neo2299 wrote: »

The charge controller hadn't been screwed down yet so it was leaning....Once I straitened it out and screwed it down everything worked great.....

Nice to hear that it's now all screwed up properly

SkiDoo55

Re: Help setting up Xantrex XW4548 x 2 system

Sounds like anchoring it caused a connection to be made. Might want to retorque all of your connections to both and make sure no wire insulation is in the pressure connections?