Hello - First Post

krsmichael

Hello, my name is Michael. I purchased and installed an Xantrex XW system last year. I self installed a 9.1 kW ground mount system. The system consists of 36 255 watt Mitsubishi panels, two XW4548 inverters, 3 MPPT60 charge controllers and 390ah battery back up. You can see more details here.

http://www.simpsonsworld.net/Solar/Solar/Welcome.html

After I had the thing up and running, I had a desire to monitor the system. I bought the Xantrex XW Gateway. The device is...okay. The problem I ran into is that the device requires Yahoo Widgets which has been deprecated by Yahoo. It took me six hours to find a source for a Yahoo Widgets installer because Yahoo won't even let you download the installer. I found the latest, and good installer here.

http://lightquick.co.uk/jdownloads/virtuemart-extensions-available-to-download-4.html?Itemid=242

It is too bad because this guy is a VERY talented widget developer and Yahoo pretty much kicked him to the curb. May I suggest a small donation to the guy for providing the valuable service?

But this brings me to my comment. Because I didn't like how limited the gateway and widgets are, I am writing my own application for monitoring the gateway. You can find my application here. There are some rough edges, but you can get the jist of where I am going. I had noticed others commenting on desired features, so I thought I would make it available so as to get feed back. You need to have an XW Gateway for this thing to work. The application is for Windows right now. It is written in C++/QT so to put out a Mac OS version or a Linux revision would merely require a recompile. I'm just ready to support that yet.

http://www.simpsonsworld.net/XWGateway.zip

Keep in mind that this is not my job. It is merely a hobby project so be patient and civil.

Michael

BB.

Re: Hello - First Post

Welcome to the forum Micheal.

From what I have read, there is not much that is easy and powerful for remote monitoring a whole system like the Xantrex. Perhaps a few folks here can help you or look at the widget developer's work.

I don't know if poster "Tall Girl" (she has not been around here recently) has any Xantrex solutions--But there may be some items of interest for you:

http://www.greenhousepc.com/greenMonitor.html

I have one concern with your system... Perhaps it is a typo. 390 AH (at 48 volts) battery bank? For many different reasons, I would be suggesting a 900 AH @ 48 volt battery bank minimum for your system (assuming Lead Acid batteries).

-Bill

gww1

Re: Hello - First Post

Michael
What voltage are you running from the panel aray to the batteries? IE; 180'
Thanks
gww

krsmichael

Re: Hello - First Post

It is not a typo. The batteries are AGM. What are your concerns?

The app I am writing is going to be backed by a Sqlite database. I'll put it in open source when I get it a little farther along.

krsmichael

Re: Hello - First Post

The voltage is running about 119 volts.

BB.

Re: Hello - First Post

AGM's can handle very high surge currents... So the flooded cell Lead Acid rule of thumb for ~100 AH @ 48 volts per 1kW of Inverter Rating (assuming 2x surge support for a ~C/2.5 rate of discharge) would not apply.

However, we have seen some issues with "smaller" AGM battery banks and large solar arrays. Many/most MPPT charge controllers run a "sweep" to find the peak of the V*I curve (maximum power at what Voltage). And the controller needs a place to dump the energy. It appears that a smaller battery bank (AGM or otherwise), may not be able to sink enough current during these sweeps.

Also, I am not sure of the time constant of the larger MPPT charge controllers (say you have max array power going into the system, and a balanced amount of wattage being drawn off by the AC inverter--And the AC power turns off--How quickly can the charge controller stop the current flow before the battery is "over voltaged").

I have read a few such systems that have had battery bus over voltage faults reported by the XW inverter (if I recall correctly--the fault voltage was 72 volts).

So, that was my concern, and the suggestion of ~100 AH @ 48 volts for every 1 kW of solar array rule of thumb too.

Anyway, that was my concern/questions.

-Bill

Photowhit

Re: Hello - First Post

Was any of Solar Guppies software aplicable to XW? I'm guessing not as I think Bill has played with it...

BB.

Re: Hello - First Post

Not this "Bill"... I am strictly low tech (pencil and paper for a few years--Just looking at the unit every few weeks now).

-Bill

tallgirl

Re: Hello - First Post

BB. wrote: »

Welcome to the forum Micheal.

From what I have read, there is not much that is easy and powerful for remote monitoring a whole system like the Xantrex. Perhaps a few folks here can help you or look at the widget developer's work.

I don't know if poster "Tall Girl" (she has not been around here recently) has any Xantrex solutions--But there may be some items of interest for you:

http://www.greenhousepc.com/greenMonitor.html

I have one concern with your system... Perhaps it is a typo. 390 AH (at 48 volts) battery bank? For many different reasons, I would be suggesting a 900 AH @ 48 volt battery bank minimum for your system (assuming Lead Acid batteries).

-Bill

I have nothing for Xantrex. The CANbus related communications bus they use is a real bother. I've not been contacted by many people about Xantrex support in the past four years, so there's no financial incentive there either.

tallgirl

Re: Hello - First Post

BB. wrote: »

AGM's can handle very high surge currents... So the flooded cell Lead Acid rule of thumb for ~100 AH @ 48 volts per 1kW of Inverter Rating (assuming 2x surge support for a ~C/2.5 rate of discharge) would not apply.

However, we have seen some issues with "smaller" AGM battery banks and large solar arrays. Many/most MPPT charge controllers run a "sweep" to find the peak of the V*I curve (maximum power at what Voltage). And the controller needs a place to dump the energy. It appears that a smaller battery bank (AGM or otherwise), may not be able to sink enough current during these sweeps.

Not sure where 100Ah per kW DC came from.

AGMs are problematic in grid-interactive systems because they stay fully charged most of the time (that grid-interactive thing) and have VERY low acceptance currents at high states of charge. My now-ancient FLAs take about 1.5% of the C/20 rate at the end of absorption.

In my experience, Xantrex gear is slow in responding to the behavior of other components and I've seen high voltage excursions on large arrays. In my opinion the only advantage Xantrex had with battery-backed gear was the ability to parallel their larger inverters. Now that the Radian is out in the market, I think Xantrex has lost their last and only advantage in the battery-backed market.