Some commentators have recently blamed “solar advocates” in Pakistan for overlooking the inability of solar systems to provide reactive power and inertial support to the electric grid. They are apparently correct, but, as we clarify below, a deficiency only arises if distributed solar is viewed through the lens of the traditional grid, which relies on serving consumers via gigantic, central-station power generation using extended transmission and distribution (T&D) systems. Distributed solar and similar technologies have opened new vistas of serving consumers’ electricity needs at or near their sites, making the conventional grid largely redundant.

The conventional grid (generation, transmission, distribution, and delivery systems and facilities taken together) is a complex undertaking and very difficult to explain in non-technical terms. Two critical concepts to understand are: (i) a consumer’s demand for “electric power” (kW or MW) at any given instant for different services (heating, cooling, lighting, preserving food and medicines, industrial processes, and others); and (ii) the duration for which this demand remains on the grid, “electric energy” consumed (kWh or MWh).

Electric grids are built and operated to ensure that sufficient generating and T&D capacity and fuel stocks are available to serve consumers’ aggregate demand for power and energy anywhere in their systems, from the next moment to the next couple of decades, or even longer.

Modern grids operate on the principles of electromagnetic induction (alternating current “AC” systems). In these systems, power flows back and forth 50 or 60 times every second, depending on where in the world we live. This is in sharp contrast to direct current or “DC” systems in which power flows in one direction only.

Throughout the system (from generation to end-users), electric grids rely on materials that oppose the flow of power in various forms: resistance, inductance (magnetic fields), and capacitance (electric fields). The last two are also called inductive........

© The Friday Times