What power source to use in nature?

Question

Batteries

The task is this - there is a device that is planned to be installed in nature with completely autonomous operation. Consumption - 5V, 2A, 7-10W, ~1000mAh / hour. Even if you use a 10w solar panel + a battery with a capacity of 20000mAh (filled, respectively, in the region of 19000mAh and given out in the region of 13000mAh), then given our latitudes (Moscow), there is a high probability that the solar panel simply will not have time to charge the battery during daylight hours. The space for installing the device is extremely small, i.e. fields of solar panels with windmills will not work.
Question - is there a way out of this situation?

Answer 1

As an option - hydroelectric power station - https://www.youtube.com/watch?v=IaDzf8qWHHk
Is the gas generator not suitable?