seriesresistance

Series resistance refers to a configuration in which electrical components are connected end-to-end so that the same current flows through each element. In such a configuration, the total resistance is the sum of the individual resistances, while the current remains identical through all components and the voltages add up. This contrasts with parallel arrangements, where voltages are the same across components and currents divide.

For n resistors with resistances R1, R2, ..., Rn connected in series, the equivalent resistance is Req = R1 + R2 + ... + Rn. The current is I = V / Req for an applied voltage V. The total power dissipated in the series string is P = I^2 Req, which is also the sum of the power dissipated by each resistor (P = I^2 R1 + I^2 R2 + ... + I^2 Rn). The voltage drop across each resistor is proportional to its resistance, so larger resistors in the string take a larger share of the total voltage.

In real circuits, parasitic or intentional series resistance can arise from conductors, contacts, and component leads. This series resistance can cause voltage drops, limit current, generate heat, and reduce overall efficiency. Designers mitigate these effects by using thicker or shorter connections, low-resistance components, or arranging circuits to minimize the number of resistive junctions.

The concept also appears in solar cell and photovoltaic module modeling, where a series resistance parameter represents resistive losses in the cell and interconnections. Higher series resistance lowers fill factor and maximum power, especially at higher currents.