Xantrex XW6048 Grid-Tied System Configuration Question
I purchased a home in Colorado and inherited a solar electricity system that I think is not working as expected. As a point of reference, I do have an Outback grid-tied system back home in Maryland that has been functioning since around 2008.
The Colorado system is a Xantrex XW6048 single inverter with about 4kW of PV in two strings going to 2 MPPT60-150 charge controllers and a 48V 415AH battery bank.
As mentioned the system is grid tied and the odd behavior is that when the grid is active (AC1 input), the system never inverts available DC power from PV. It always stays in AC Passthrough mode. I know there is PV available because when I shut off the AC1 input breaker (disconnecting from grid), the system immediately goes to inverting PV and battery power to supply the loads (have been running in the 400-800W range this morning).
The system is generally with the default settings as I did a system reset to factory defaults earlier. I would think that out of the box, the system would take any available PV power and power loads up to its max collection capacity and then supply the rest with the grid like my Outback system does in Maryland.
And since I never noticed this in Maryland since my system is also designed to sell-back excess PV to the grid, the Colorado system seems to throttle itself down to the current load. i.e. if my loads are 350W, it will supply that amount of power. If I turn on more stuff and bring the load up to 750W, it will power up to supply that load. And when I then turn off these additional loads, the supplied PV power goes back down the supply only the lower load.
The behavior that I would expect is that when there is PV power available, it would a) charge up the batteries and b) power the loads up to its supply potential. It would then use the grid to supplement either a) or b) if the loads are greater than the available PV. If the available PV is greater than a) + b), then it should sell that power back to the grid. Ideally, my system would maintain the batteries at full continually and float it indefinitely until there was a power outage. Assuming the batteries were kept fully charged, any PV power above and beyond my loads plus whatever is needed to float the battery bank should be sold. As it's a vacation house and the loads are nominal 85% of the year, I would expect that there would be an excess of PV generated compared to total loads over the course of a year, but that has not been the case. I did hook up a ComBox while here at the house this week and can see this behavior clearly.
Any suggestions on what to look for in the configuration? I am assuming a) the system is wired correctly (there was a business card of a solar company inside the inverter when I opened it up, but a phone call to the number on the card yielded a disconnected message) and b) that it was functioning fine at some point in time before I purchased the house. I'm assuming the solar has been with the house since it was built in 2008. Thanks for your thoughts.