Lý thuyết điện & an toànElectrical theory & safety

Before touching a solar panel, inverter, or battery storage system, anyone working in the solar energy industry needs a firm grasp of foundational electrical principles and a set of non-negotiable safety rules. This chapter builds that foundation: from Ohm’s law and power, to power electronics inside the inverter, to the unique hazards of DC electricity and how to protect a system against them.

For: newcomers reading for the first time, technicians who need the power electronics and system protection sections, and sales staff who need to understand the underlying principles so they can explain to customers why a system is designed the way it is.

Quick Summary

The entire electrical industry rests on two formulas: Ohm’s law states that voltage equals current multiplied by resistance, and power equals voltage multiplied by current. Understanding the four quantities (voltage, current, resistance, and power) means understanding the majority of design decisions.

Modern solar PV practice prioritizes raising voltage and reducing current, because heat losses scale with the square of current. At the same power level, lower current means cooler cables, lower losses, and greater safety.

DC electricity carries a hazard that AC does not. A DC arc cannot self-extinguish because there is no zero-crossing where the current drops to zero. For this reason, solar PV systems require dedicated cabling, correctly rated protective devices, and their own safe operating procedures.

Learning Path

The chapter consists of six documents, arranged from foundational principles through applied safety.

Core Terminology

Foundational Principles for the Entire Chapter

Two ideas run throughout every document that follows. First, higher voltage with lower current is always preferable in terms of losses and safety at equal power, because the heat generated in a cable scales with the square of current. Second, DC electricity is more dangerous than AC during a fault because a DC arc has no zero crossing to self-extinguish, which means every component on the DC side must be selected and operated to a stricter standard.