Put grid power into gen port of conext xw+ 5548

[underdog5004]

Hello
I have a dual xw plus system in my solar shed on the back porch . My house is connected to the grid but I have a solar shed out back that is off grid. I plan to run AC out from the shed to a transfer switch that will feed a sub panel on my house. My intention is to run my home from my solar shed as much as possible.

However I only have 600 amp hours of batteries and 6 KW of solar panels , so there will be times when I need to go back to the grid.

As an intermediate step between on and off grid, I would like to implement charging of the batteries from the grid power. I know I can run a 240 volt line from my main panel into my solar shed, but I'm concerned that if I put the grid wires into the grid port I open myself up to accidentally exporting even tiny amounts of power back to the grid. I have no agreement with my local utility company, and this might land me in some hot water.

So my idea is to run 2x 120 volt legs from the grid into the Gen port of the conext inverter. Will this cause any problems? Will I need to run a neutral or can I just use the two legs and assume the charger will draw from them evenly? What am I missing? What am I not asking about?

To avoid all this complexity, I could purchase an eg4 chargverter but if I can use the existing 120 amp charger in the xw inverters, I'd prefer that.

As an addendum I want to clarify that I reference putting the wires directly into the Gen port of the inverter above, but electrically I would be connecting the grid to a bus bar that feeds a couple AC Breakers which then feeds into the Gen ports of the two inverters.

 

[RCinFLA]

If you have AC1 sell back feed set to zero you do not have much chance of back feeding to grid. There is no difference in back feed prevention on AC2 port and AC1 port. Both ports prevent inverter back feeding by separate CT sensors on each port. Believe AC2 is hard set (no user changeability) to not allow back feed because it is port to be used for a generator.

Hardware-wise, there is no difference between AC1 and AC2. Both have their own CT current sensor, pass-through relay and both connect to inverter/AC output when their respective pass-through relay closes (only one pass-through relay closed at a time).

Primary difference is the acceptance frequency spread allowed for AC 1 (grid) is much tighter than AC2 (gen) ports. The wider the acceptance freq spread the longer it can take for inverter to lock on AC input because it may have to search across a wide frequency spread. This is just software.

AC1 also has priority on connect. If running generator on AC2 and grid comes on AC1 it will give up AC2, resync to AC1 and reconnect.

 

[Cmiller]

So my idea is to run 2x 120 volt legs from the grid into the Gen port of the conext inverter. Will this cause any problems? Will I need to run a neutral or can I just use the two legs and assume the charger will draw from them evenly? What am I missing? What am I not asking about?

You won't have any problems feeding into grid or gen ports. As @RCinFLA mentioned, each input has it's own CT sensors and the only way it'll even "think about" selling is if you turn on grid sell specifically in your menu. The gen port does not even have a sell option, so no worries there.

In reference to the 2x 120V legs running to the inverters: those will need to be the opposite legs, so you would be best running 240V. And as far as the neutral goes, the neutral is common in the inverters, so as long as the load neutral is electrically connected to the grid electrical system, you will be fine. Just make sure that the neutral is not switched somewhere! If the XW doesn't see a neutral it won't connect up, but you should still be careful with that! A breaker panel that somehow ends up with an open neutral while it has the 2 legs hot, will fry things real quick! Essentially anything being plugged in will cause that hot leg to loop to the neutral bar and feed 240V to other 120V appliances!

Personally, I would probably run grid into the grid terminals and set up a PB30 inlet box (L1430 cord inlet) with the gen terminals. That way, if grid happens to be down for an extended period of time, you can always borrow or rent a 240V gen for backup charging.

To avoid all this complexity, I could purchase an eg4 chargverter but if I can use the existing 120 amp charger in the xw inverters, I'd prefer that.

The Eg4 chargverter is really sweet, but a benefit of using the inverters' chargers is that you get passthrough during charging, which get's those batteries charged up much quicker! And if you want to, you can even leave grid turned on all the time, with the inverters automatically reverting to grid power when the batteries run low.