A limited-power-limited-energy system design approach for remote areas

This paper introduces a new design approach when both power and energy resources are limited and unreliable. This approach is most suited for the power networks with intermittent availability and poor quality of power signals. This approach is also useful for remote off grid or disaster area power systems for having similar issues. The power system comprises four power sources namely, grid, diesel generator, solar panels and batteries. The energy use is prioritized as solar first, then grid, then battery and lastly diesel generator. The poor quality of grid power signal is addressed by converting the AC power signal into a DC signal and then using the solar inverters to generate well-regulated AC power signal all the time. The issue of limited energy availability is dealt with the introduction of load management. Instead of using groups to balance loads on each of the three phases, the wiring of the site was designed to have many load groups keeping in view the operational priority of loads, which is not catered for in normal wiring practices. This approach needs to be adopted in all new installations. In the event of unavailability of solar, grid, and diesel genset power sources, the battery becomes the only source of power and energy. The load management ensures that this source of last resort lasts the longest while supporting the most critical loads such as essential lights and lifesaving medical equipment in the case of disaster areas. The cost of operation in this design increases to less than 20% when compared to continuous operation on the grid whereas in comparison to diesel power generation, it results into more than 50% increase. The payback of solar power generation with battery backup in comparison to the grid is around 6 years. It is less than three years when compared to diesel generation.