minerva said:
> I am really curious now. 
> Was Solark designed by Solark and custom-built by Deye or did Solark create custom firmware for an existing Deye design?

no on both cases

design was done by keith slough, sunsynk
ngigbo deye ( holding company of both deye and sunsynk) holds the patents.
sol-ark simply slaps a stcker on it and provides local support, and gives a markup of 300%

sunsynk - exclusively sold in uk, africa's and nz/aus
Deye    - rest of world
Sol-ark - usa and territories

source:
https://diysolarforum.com/threads/deye-hybrid-split-phase-inverters-discontinued-in-favor-of-sol-ark.27830/post-484320