1 hour ago, BigC said:

Then you lose the contribution of the 3rd string during load shedding, which is kinda when you need it most. It's a tossup .. it's the cheaper solution, but not elegant at all.

You need to install CT clamps on both the Deye and the Solis grid-tied inverter. Both CTs must be installed on your utility incomer (main grid supply cable into the DB).

• The Solis CT is critical it activates the Solis’s built-in export limiter. Set the Solis to allow a small utility feed-in (±20W). This gives a buffer so the Solis can quickly throttle its own output and prevents excess power from leaking back through the Deye to the grid.

• The Deye CT should also be on the same utility incomer so the Deye has accurate whole-house grid flow data for its own zero-export / power control logic.

This dual-CT setup on the main incomer usually resolves the Deye “leak” / backfeed issue, especially with older Deye firmware and slower-reacting Solis minis on the GEN/AUX port.

Your Deye is currently the bottleneck for clean blending and easy expansion.If you have the budget,

I would strongly recommend upgrading to a Solis S6 8kW Pro hybrid.

Reasons:

• Superior power blending (Victron-like behaviour).

• Excellent generator integration on the grid side, keeping your AUX/Smart port free.

• Very strong AC-coupling support connect your existing Solis minis to the backup port and set to “Export to Load Only”. Works great in off-grid / micro-grid mode with reliable frequency shifting.

• Much larger PV array support and 200% overload for 10 seconds.

• Overall better Tier 1 hardware and long-term reliability compared to the Deye (Tier 2).

This would give you a much cleaner and more capable system essentially you would have a micro grid that can work off grid with Micro/ Mini grid tied inverters and generator integration on the grid side and still have the aux port free for additional Grid tied inverters.

With both CT clamps correctly installed on the utility incomer as described, your current Deye + Solis mini AC-coupled setup should stabilise nicely. Both brands are decent, but for hybrid + AC-coupled work the newer Solis S6 is my personal preference.Just my hands-on recommendation.

Edited June 9Jun 9 by Powerforum Store

7 hours ago, BigC said:

you lose the contribution of the 3rd string

Ok, leave the Solis but only run the generator at night... elegant.

@Powerforum Store.. thanks for knowledgeable response. And @frivan for your simple suggestion.
Since the generator is a manual start, there is no hardship in operating a bypass switch from grid to generator, so I will implement that this week.
The budget is a concern, so the suggestion to live with the Solis on the gen port and add the CT makes sense and is easy to do, since most of the work has been done already. If the weather permits enough sun this week I should have my answer soon.