This is from Boeing in 2012, referring to standard 90kVA receptacles.
The 787 airplane utilizes two (2) forward ground power receptacles and one (1) mid-aft ground power receptacle. Each receptacle is rated at 90 kVA, as is standard on all Boeing current production widebody airplanes.
By design each receptacle can support continuous 90 kVA and a peak power consumption of 112 kVA for up to five (5) minutes regardless of the output capacity of the Ground Power Unit (GPU). For continuous supply, the airplane will draw less than 90 kVA from any receptacle.
Although the 787 is designed to perform a normal gate turn with two 90 kVA GPUs, Boeing recommends that a third 90 kVA GPU be available for non-normal engine start due to an inoperative Auxiliary Power Unit (APU).
Solid-state GPUs used for powering the 787 aircraft should meet or exceed the following inrush current levels:
Worst Case Max Current: 1100 Amps peak
Average Max Current: 730 Amps peak
Decay to less than 500 Amps within 10 msec
Decay to steady-state Amps within 130 msec.
Solid-state GPUs should be adjusted to the above specifications.
From your comments, it appears you want to power a 747 using external batteries for a one-hour turnaround. For a 747, this would be a very short stop, typically it would be closer to 2 hours
To establish the capacity required, you would need to look at the input spec for the inverter you intend to use that would provide the required two 90kVA outputs. The quality of the output of the GPU inverter would need to meet specs, such as DFS 400 / MIL-STD-704E / ARP5015A.
The above info was obtained from the internet, as I am only familiar with and have experience of the aircraft side of things. If the aircraft does not like the quality of the ground power, it will kick it off.
Looking at the energy required and the cost of batteries, I’m not sure if this is a feasible possibility.