The entire installation is not yet operational, but today I had some time and assembled a provisional measuring station. But first things first:
The inverter arrived without damage (it was well packed). It gives the impression of a somewhat refined design (to what extent will become clear when it starts to operate under a higher load for a longer time).
It has robust power terminals for PV and 230V AC I/O. Battery connection - 25mm2/M8 cable lugs (tight, terminals of this size touch each other).
The fan speed is infinitely adjustable; after starting, they run continuously and increase speed with increasing load (of course, the noise also increases). Airflow direction - downwards.
A few measurements:
After starting the inverter via the battery, the power consumption is 1.3 A at 53.4 V (inverter without load). I think there are inverters with similar power and lower b/o consumption.
Fans running at low speed are quiet.

Example - Charging the battery through a grid-tied inverter:
Battery charging current 24A at 54V
Power draw from the grid 6.3A at 228V

Example - battery-powered inverter with resistive load:
Battery current and voltage: 20.9 A / 51.7 V
Load current and voltage 4.22A / 228V
Current measurement with a clamp meter (I don't know the error margin).
Voltage measurement with a digital voltmeter.
I still managed to connect some of the photovoltaic cells - the inverter works correctly with the photovoltaic cells.
In the set, I have two (each 1 m) cable sections (they look like 25 mm2) with crimped cable ends for connecting the battery.
It remains to mention the manual in Polish with a detailed description of the inverter settings (very useful for commissioning).

Something is wrong with posting reviews. Another attempt ended (I believe) in failure.
Rating too high/too low?
On a five-point scale, I can easily give 4+.

So far, everything is fine, thank you. You were quick. It is worth ordering here!

It loads quickly, works without issues, everything is fine. The investment is worth it, as the results are very measurable;-) Both the structure and other elements were carefully made.

I am very satisfied with the product, high quality, fast delivery, and I would like to buy more of our products in the near future.

Everything worked fine during the installation the first time.

Acquistato il 08/09/2023 e posto in opera il 01/012024. Do 2 stelle perché purtroppo non carica l'accumulo pur avendo effettuato le impostazioni utente secondo le caratteristiche specifiche delle batterie utilizzate. Visto che è in garanzia confido di poterlo rendere e avere in sostituzione altro dispositivo con caratteristiche equivalenti e perfettamente funzionante.