Webinar - AC Coupling for Solar Application

[@sitechca70]

The more I read about the XW+ and XW Pro 6848, it seems like it has one big shortcoming in AC coupled mode. Refer to the diagram (page 31) at 18:30. The load is split into Backup panel (where the AC coupled PV inverter is) and Main panel (large loads like AC, Oven, Dryer). How will this configuration support Load Shave (for TOU offset) for the loads on the Main panel? It has no knowledge of the power flow in the Main panel. Tesla Gateway has CT there for this very purpose. Looks like Conext can support external CT but only in DC coupled mode.

[@eampr]

Very interesting information about AC coupling. I have two questions I would like your inputs. I just bought a Conext XW Pro 6848, GateWay, and Mini PDP. I'm installing them to my Enphase M250 micro-inverters with net metering. First, to handle frequency shifting do I have to replace my Enphase Gateway Envoy S for the Envoy R. As far as I know the Conext XW PRO can handle frequency shifting on its own. Second, I'm planning to buy a Li-Ion battery but I'm not sure whether this battery technology is a suitable fit for the Conext XW PRO.

[@thhillbillyinventor105]

Can you do one on the ac coupleing smart charge for sw

[@SESolar]

Thank you for the suggestion!

[@thhillbillyinventor105]

@@SESolar thanks I am setting one up and you guys would be the only ones I've found on the net to have a vid of that

[@andyfeimsternfei8408]

AC coupling can be done so much simpler than these schemes and so much more efficiently. Frequency shifting to regulate inverter output and battery charging is a bad idea. Direct control of inverter output in response to varying loads and battery state of charge while maintaining 60 Hertz is far better. I have custom built my own system using a PLC to control solar inverter output via Modbus to maintain 100% soc on the batteries while matching the AC loads.

[@dannaigambi8949]

It is great to learn that one can use a PLC to control a solar inverter output via modbus to maintain 100% SOC on batteries while matching ac loads. Could you kindly share how this is done?

[@marcostube777]

Does SMA Sunny boy are able to receive Modbus commands to curtail their output? Want to know more about your PLC control

[@thhillbillyinventor105]

Make a video of how this is done

[@andyfeimsternfei8408]

@@thhillbillyinventor105 I will if I ever get time. I am not a KZbinr. Conceptually most grid inverters have export limit conrols which permit you to limit the power exported to the utility. Many use Modbus based on the Sunspec Alliance standard. So this allows the output of the inverter to be dynamically turned up or down to maintain the set export limit. So you can use a PLC or other controller to dynamically "spoof" the export power value, substituting your storage battery voltage. This is done using a PID in the PLC with the battery voltage as the process variable, the battery full SOC as your setpoint and the export value as the output . You disconnect from the grid, start your battery inverter to power your AC loads, your grid solar inverter starts up after 5 minutes. If the battery voltage is less than 100% SOC, the PID drives the output (export power) low and the inverter proportionally increases the solar output. If you increase your AC load the battery outputs to meet the demand, dropping the battery voltage. The PID then decreases the export value causing the solar inverters output to increase to carry the AC load and recharge the battery. Think of it this way: the battery acts like an accumulator or cushion. If loads increase, the battery outputs energy to meet the demand. The battery voltage drops and the PLC sends a less than export value to the solar inverter to increase output until the battery voltage is restored to 100% SOC. So the solar inverter proportionally ramps up and down to meet the AC loads and to maintain 100% SOC. Of course this is up to to limits of available solar energy. When it falls short, the battery carries the load. When the sun comes back, the solar begins to recharge the battery and carry the AC loads. My 35kw system works great using two golf cart battery banks connected to a 10kw inverter. I can even run my welding shop off-grid and the batteries, AC inverter and solar inverters just ramp up and down together to meet the varying loads of welding and stopping. Why they ever came up with frequency shifting as a way to control battery charging is beyond me!

[@andyfeimsternfei8408]

@@marcostube777 I don't know but I'm sure they use some protocol for import/export meter control. I'm doing it with Solaredge and it took a bit of hacking. Their US tech support dosen't have a clue! Sorry, I just saw your comment.