A simple and inexpensive solar panel can generate 30 watts, easy - that's more than enough for a typical UTH that can in turn generate plenty of heat for the snake tank. Sort of the electrical equivalent of importing some solar heat.
Alternately, you may find a way to configure the tank such that some basking rocks can collect heat from sunlight during the day - but be aware that sun shining in a tank can get really too hot.
Alternately, you may find a way to configure the tank such that some basking rocks can collect heat from sunlight during the day - but be aware that sun shining in a tank can get really too hot.