Solar installers wire PV modules together constantly, but how they’re connected, in series or in parallel, changes how the whole system performs. This lesson from SEI’s RE102: Basics of Electrical Theory for Solar Applications looks at what happens when modules are wired in parallel: why the current goes up, and why the voltage doesn’t.

What Parallel Wiring Does
In a parallel connection, every module’s positive terminal ties into one shared positive point, and every negative terminal ties into one shared negative point. That single design choice creates two separate outcomes:

1. The voltage stays the same: Any components wired between the same two points always share the same voltage across them, a basic rule of circuit theory. So if each module in the array is rated for 50V, the array’s combined voltage is still 50V, no matter how many modules are added.
2. The current increases: Each module contributes its own flow of electrons through its own path, and where those paths join becomes, electrically speaking, a wider path, so more electrons can cross a given point over time. Wire two 10A modules in parallel and the array can deliver 20A.

Why it Matters
In a solar system, wiring modules or batteries in parallel is how installers increase current capacity to match what their system needs, without changing the voltage a charge controller or inverter expects to see. This isn’t just a PV array concept; it’s the same principle behind the wiring in any building: every outlet on a breaker panel needs the same voltage, while current draws up as more devices switch on.

Learn the Fundamentals, Free
RE102: Basics of Electrical Theory for Solar Applications is a free, self-paced course covering voltage, current, resistance, and how series and parallel circuits affect a PV array. Enroll and start today!