DC buffer with a Tesla Powerwall 3?

[Andrew Hamilton]

Hi all - My Powerwall cutover, once the gateway detects a loss of mains power, is around 200ms before the battery storage takes over. This is usually enough to knock out the Miniserver. In researching a solution, I came across DIN-rail mounted DC buffers that use capacitors instead of another battery. It seemed like a pretty clean and simple solution so I was wondering if anyone else has tried one or if I am missing something?

The Mean Well DBUF20-24 is available for £110 or so and should provide at least 400 ms of buffer for my Miniserver and a few extensions (only mains lighting). It is designed to buffer 20a for 350 ms. 

Thanks.