I've been asked to build a back up system for a grid connected estate. We haven't done many of these and I thought it best to ask those who have some questions before I go about reinventing the wheel.
Here's the existing infrastructure.
1) 400amp Metered Main Distribution Panel with six 200amp feeders to various sub-panels on the property
2) 400amp ATS and 100kw Kohler rapid response generator
3) 20kw ground mount array with (2) SE Inverters located at the array. Feeder from array is 1,000 ft to Service. Six years old and wiring is janky.
4) Data logging for the last year shows peak demands of almost 40kw. This could increase as several of formerly vacant guest residences could be occupied.
My go to is almost always Schneider, however in this instance when I looked into a quad stack, or more It seems like some type of controller is needed to prevent imbalanced current passing through the relays during transfer. That left me a bit concerned. Has anyone successfully stacked 4 or more XWPROs?
Then there is the matter of AC or DC coupling? I really want no part in having anything to do with SE. The inverters are already looking pretty weathered taking the brunt of the prevailing winds and storms (they are mounted to one of the ground mount poles). Seems like a great waste to pull out the 4/0 feeders and replace strings. My other hesitancy with AC coupling is that we would lose PV monitoring and control.
I've also considered Sol Ark 15's, like three of them. We've got some SA systems under are belt now and the only thing I can say that I like is the speed of installation and the 200amp pass through. Other than that, they leave me uninspired. One very large system continues to have glitches that SA just shrugs their shoulders about. If we were to do three 15's, what's the preferred combining method? All that I can come up with is a custom 400a panelboard w/ three 200a breakers.
Price is not a consideration for this project. The new owners of this property (which is plagued with outages) have tasked me with building something that is ultra reliable and good take over in a situation where the grid is no longer available.
Any suggestions or tips are appreciated.
Michael
