White LEDs are about 3V at low current. They probably connect them in two groups in series. The LEDs in each group are all in parallel and the maker hopes that only a few burn out and that you don't notice. Then they use a single current-limiting resistor.
AA cells can't provide much current so 128 LEDs is rediculous. Only 20 LEDs operating at 25mA each will be extremely bright.
6 AA alkaline cells provide 9V for a few minutes then drop to 6V in 2.5 hours with a 500mA load. LEDs in parallel and with two groups in series will be about 6V and a single current-limiting resistor sets the current.
With 64 LEDs in each group then each one will have a max current of only 7.8mA.
I raised the issue in a previous thread re a 31 LED torch too.
That one drew nearly 1 amp from 3 x AAA batteries and the batteries did not last at all.
I changed the handle completely to take 3 C cells and it runs fine.
The LED's are fine, the battery capacity was well underrated.
This 128 Led beast is probably the same. Ideally it requires C or D cells to get any proper use out of it. AA's in that case are also heavily underrated for that high demand.
There isn't any solar power when it is dark. If there is sunlight then the flashlight wouldn't be needed.
I have a pretty big 1.8W solar panel. Its current is rated at 150mA but the max I got through a closed window at noon was only 50mA. It produced 100mA with the window open. The window was clean. An hour later the current was half.
It would take weeks or months for some little AA 2500mAh Ni-MH cells to fully charge.
Drag an extension cord around behind a flashlight?? I don't think so.