[RE-wrenches] Request for Enphase inverter comments

[Peter Parrish]

Normally, I have good things to say about Xantrex and their GT and XW class
inverters. I personally replaced four GT units a while ago as they dealt
with their "capacitor" problem. 

This post is about the XW product.

We installed a XW6048 with two charge controllers, a 4,200 W-dc PV array and
a 550 A-hr, 48 Volt AGM battery bank.

Things went fairly smoothly in the install, but we encountered a "sawtooth"
in the AC output in sell mode. Over a period of approximately 30-45 seconds
the inverter charger would ramp up in output power (say to 2,800 W-AC), then
snap down to zero and start over again. Although it is hard to follow what
is happening in real time, it would appear that the ramp up is slower than
the ramp down.

I spent four trips to the customer's home to try to resolve the issue with
the help of Xantrex tech support. I even went to the trouble of making
appointments with tech support, before going to the customer's home. With
the help of tech support, we mucked around with the grid support voltage,
float voltage, maximum sell current, two-stage vs three-stage charging, and
checked a host of operating modes/settings. I spoke with every tech support
person with knowledge of the XW system, and I double-checked my connections
(torque). The last thing that tech support recommended was upgrading the
firmware.

I finally convinced Xantrex to open a trouble ticket and I escalated the
issue to their Product manager Ericka Yedid.

Since the system was manufactured in Aug 2007, Xantrex has recommended
upgrading the firmware, and has promised to supply a dongle, files and an
up-to-date XW configuration tool that can be used with a laptop to
accomplish this end.

This is our first XW install and we are not experts on grid-tied battery
backup systems although we have installed four now. Does anyone have
experience trouble shooting these units? Anyone seen the sawtoothing I
described? What is the quality of post sales tech support for this product?

- Peter

Peter T. Parrish, California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish at calsolareng.com