My idea with additional cooling for Deye inverter to reduce both: noise and temp. Concept is proven.

@ModernUkrainianHomestead
Simple old computer fans are working extremely well in a combination where some of them are at the bottom blowing cold air inside the heat sink, and some of them are on top working in exhaust mode.
However, since I picked those that were by hand nearby and are free of charge - this means that the system is not 100% perfect. I now need to figure out some nice, quiet, big, and productive fans, and then attach them nicely as per the current concept.
I bet, 120x120 mm will be exactly the correct size to look for.

[@bermudatriangle2036]

how do i get a cheap battery, what do you recommend?

[@ModernUkrainianHomestead]

Go for LiFePO4 DIY box like Masons or Seplos + cells Eve, CATL or Hithilum, up to your preference. The bigger you go - the cheaper it is. A friend of mine just recently bought one, 14.3 kW of storage, for $1700 only...
Where to buy - Alibaba.