For energy security of the country, electricity energy generation from alternative (renewable) energy sources is fundamental, as Lesotho has no known fossil fuels for electricity generation. Since generation from alternative sources is usually far from the end users, learning how to evacuate this energy becomes critical. The structure of electrical energy systems (both AC & DC) from the perspective of a national grid, transmission and distribution networks will be presented. The components included within the electrical power system, the models used to represent each component and basic analytical techniques used to combine these component models into an electrical energy system are covered. Models will include generators, power transformers, lines, cables, induction motors, load and power electronics devices. Analytical techniques will include per-unit, phasors and power flow. Renewable energy generation and the integration of renewable energy into the modern power grid will be introduced.