The original plan was to use the three Ecoflow components in my RV in the summer and transfer them to my house in the winter to offset electrical costs with a DIY solar array, but it is turning into a maze of confusion for something that should be super simple. 10.8 kWhr storage is likely a perfect size for a small house to cut back a significant portion of the electric bill so it seemed like the logical way to use their products in the winter. After spending $6g+ on Ecoflow products I have to say I'm disappointed in the lack of adaptability built into their products. For that much money, the product seems quite limited as a solar storage solution. If they put a PV input of 1600W on each component they would resolve most of the complaints. Given the fact that the Delta Pro has the exact same form factor as the spare batteries, it seems like fitting the extra components in the same case with the battery would not be a problem at all.
I think the grid tie inverter with a stack of server rack batteries will be a better solution as you said. The solar on the RV is limited to 1200W so I guess that is where the Ecoflow products will stay. Why spend $6g when you can spend 10 to compensate for the lack of adaptability of a product? Perhaps I should run around with my 300lb Ecoflow set up in my trunk to find courtesy car charging ports so I can get the darn thing charged within a reasonable time frame and [save money???]. So much for Ecoflow + solar.