Question about EcoFlow River Pro 600

Don't understand the question technically...what do YOU mean?

It is true that the inverters "may"/can only feed power into the grid when grid voltage is present.
The panels produce DC voltage. This voltage is power-dependent depending on the light irradiation. It is possible to use this DC voltage to charge the EcoFlow River Pro directly via the DC voltage input, for example. However, a "device" is REQUIRED to adapt the panel voltage to the device to be charged. The permissible charging power of the EcoFlow is max. 25V - 12A (300W). The permissible power draw is "so" only 600 watts too.
In about 2 weeks I may be able to offer a possibility to obtain up to max. 1'800 Watt at 230V at short notice.
I hope that these explanations have shed more light on the subject of energy storage. Please do not hesitate to contact me if you have any further questions.
Yours sincerely * E. Hofstetter