I am entering everyone's nightmare with my local Power Company (TriCo in Tucson AZ). I live in the desert 20 miles outside of town and in June of 2025 I had installed an off-grid system (24 540w panels, 2 12000XP inverters in parallel, 9 rack mounted EG4 LL-S 48V 100Ah batteries). When the system was installed my main breaker panel (200amp) had all the circuits pulled and moved to an off grid 200 amp panel. The only circuits left in my PoCo panel are two 50 amp circuits running to the inverters (one each) grid input.
The system has been running almost flawlessly since it was installed, with the only problem being the W028 Overload, fixed by the firmware update. I have had the system do W028 twice since the update, when my pool heat pump (5kW), house A/C (5kW), Electric Dryer(4kW) and Electric hot water tank (3kW) were all on at the same time and the sun went behind a cloud. In both cases, the grid inputs covered the overload without any break in power and after 5 minutes the unit came out of overload on its own. Since then, I made changes to my Home Assistant setup to ensure that all those systems will not be on at the same time, however, the system handled it fine.
Last week I was contacted by my PoCo, telling me that they "sensed" me putting power on their grid and that since I do not have an interconnection agreement and if it happens again they will shut off my power!
I immediately turned off the main breaker for the PoCo (my system has not needed any grid power for over three weeks, so this does not affect my usual life patterns). I have also added a level 2 EV charging system since this issue began.
So, I contacted them to discuss the way forward. I informed them that the grid inputs are the only connection between my off-grid system and their grid. I informed them that the literature for my inverters claim this system is incapable of exporting power (now I have seen people posting that it may send a 2 watt transient during switching). I asked my PoCo if we can go ahead and do an interconnection agreement as I would like to keep grid service for emergency back up (they have a $20/month base fee for power).
I started trying to fill out the interconnection agreement application, which has to be done online thru their website. When I get the inverter, it is drop down menus. Of course, EG4 is on there, but the off grid inverters (12000 or 6000xp) are not. I contacted the PoCo and they told me if the inverter is not listed....I cannot use it. They told me that their list of inverters is handled by a third party. I asked them how to get an inverter added... then they informed me that their third party is CEC (California Energy Commission). That any addition of an inverter must be done thru them (CEC), and requests must be submitted by the manufacturer (EG4)
EG4: So, my question to EG4: Since your 12000XP inverter does, in fact, bleed power to the grid - are you getting it added to the CEC list of approved inverters (your hybrid inverters are on the approved list so you must have successfully got them approved)?
Community: I know I could buy a generator and tell the PoCo to come get their meter, but I would prefer grid for emergency, even at $20 per month. What are your thoughts?
Oh, I have asked the PoCo (and await their response but am not hopeful) if I can disconnect the grid connection to the inverters and use a Chargeverter.....
