How a solar system is wired

Before you size anything, you need the map: how electricity flows from a panel on your roof to powering your fridge — and out to the grid. Every design decision in this course is really about shaping that path. Here’s the whole chain in plain English.

The chain, end to end

A solar module (one panel) makes direct current (DC) at a fairly low voltage. On its own it isn’t very useful, so panels are wired together and the energy is converted and routed:

1. Modules → strings. Several modules are wired in a series chain called a string. Wiring in series adds up their voltage to something an inverter can use.
2. Strings → MPPT inputs. Strings plug into an inverter, specifically into one of its MPPT inputs (Maximum Power Point Tracker) — the part that squeezes the most power out of whatever the panels are producing right now.
3. Inverter → AC. The inverter converts the panels’ DC into the alternating current (AC) your home and the grid use.
4. Inverter → main panel. That AC feeds your home’s electrical panel. Your appliances use it first.
5. Excess → grid (or battery). Whatever you don’t use flows backward to the grid for a credit, or charges a battery if you have one.

Where the battery sits

A battery stores DC, so it needs a hybrid (battery-capable) inverter or its own battery inverter. With storage, the priority order is usually: power the home → charge the battery → export the rest. We cover sizing and coupling in Module 7.

Series vs. parallel — the one rule to remember

Two ways to connect electrical sources, and the difference drives almost everything later:

• Series (end to end) — voltage adds up, current stays the same. This is how modules form a string.
• Parallel (side by side) — current adds up, voltage stays the same. This is how multiple strings share one MPPT, and how battery units add capacity.

Keep that pair in your head: series → volts, parallel → amps. Modules 4 and 5 are entirely about getting those two numbers into the inverter’s safe range.

The words you’ll keep hearing

• Module / panel — one solar panel.
• String — modules wired in series.
• Array — all your panels together; a sub-array / orientation is a group sharing the same tilt and direction (Module 3).
• Inverter — DC→AC. String inverters serve whole strings; microinverters sit under each panel; hybrid inverters also manage a battery.
• MPPT — an inverter input that optimizes a group of panels independently.
• kW vs. kWh — kW is power (the rate, right now); kWh is energy (power × time). Your system size is in kW; your bill and battery are in kWh.

Why the layout matters

It’s tempting to think “more panels = more power,” but how they’re wired decides how much of that power you actually keep. Put mismatched panels on one string and the whole string drags down to the weakest one; oversize the array against the inverter and you “clip” the peaks. The rest of this track is about avoiding those losses — and you’ll watch each one move in the simulator’s results.

Next up: the three datasheets — module, inverter, battery — and the exact numbers that drive every choice.