Well, the population in the less developed regions of the planet cant easily get power source for our tecnology product. Then we must provide energetic autonomy in normal operation for the result of our efforts.
This could be obtained from the sun, that inexhaustible source of energy, especially in countries near the tropics. A tablet with a battery sized to the needs and a solar cell, loaded down by the sun when the tablet were out of use, may be a ideal solution.
The tempereture the tablet can support may be the great problem.