A solar array is a dozen or more panels working together, and how they’re wired into the system is one of those behind-the-scenes details that quietly shapes performance and safety. You won’t wire them yourself — it’s an electrician’s job — but understanding the basics of series and parallel wiring helps you grasp why your installer lays out the panels the way they do, and why it has to match your inverter. It comes down to a simple trade-off in physics.
Series vs parallel — the core idea
Panels can be connected two ways, and each does something different to the electrical output:
- In series (panel-to-panel, like links in a chain), the voltages add up while the current stays the same. Six panels in series produce roughly six times the voltage of one. A series-connected group is called a string.
- In parallel (all the positives joined, all the negatives joined), the currents add up while the voltage stays the same. Parallel wiring builds current rather than voltage.
That’s the whole principle: series stacks voltage, parallel stacks current. Real systems often use a combination — several panels in a series string, and sometimes multiple strings in parallel — to hit the right balance.
Why it has to match your inverter
Here’s why the wiring isn’t arbitrary. Every inverter has an input voltage window — a range it’s designed to accept, defined by its maximum power point tracking (MPPT). Wire too few panels in a string and the voltage may sit too low for the inverter to work efficiently; wire too many and the voltage can climb too high — especially on cold, bright days, when panel voltage rises — potentially exceeding the inverter’s safe limit.
So the installer’s job is to design the strings so the array’s voltage stays inside the inverter’s window across all conditions, from a hot summer afternoon to a frosty winter morning. That’s why the number of panels per string isn’t a free choice — it’s dictated by the inverter and your climate. Get it wrong and you either lose output or risk damaging equipment.
How string design copes with shade and roof layout
String wiring also interacts with shade and roof orientation, which is where it gets practical:
- Panels in a string perform as a group. If one panel in a string is shaded, it can drag down the whole string’s output (think of a chain moving at the pace of its slowest link). So installers try to keep panels that share a string on the same orientation and free of shade.
- Different roof faces often get separate strings. Panels facing east and panels facing west peak at different times, so wiring them as separate strings (or using per-panel electronics) lets each perform on its own schedule.
- Where shade is unavoidable, per-panel solutions — microinverters or power optimisers — sidestep the string limitation entirely by letting each panel operate independently. (See string, micro, or optimisers.)
So the wiring layout is part of how a good installer wrings the most out of your specific roof.
Why this is electrician’s work
A solar array operates at high DC voltages — a series string can reach several hundred volts — which is genuinely dangerous and behaves differently from household AC. Designing strings to stay within the inverter window, fusing them correctly, and wiring them safely is specialised, regulated work. In New Zealand it must be done by a registered electrician working to the relevant standards (AS/NZS 5033 for the array). This is firmly not a DIY job, and the string design is one of the technical decisions that separates a competent installer from a cheap one.
The verdict
How your panels are wired comes down to a simple trade-off: series wiring adds voltage and forms “strings”, parallel wiring adds current, and the layout has to keep the array’s voltage inside your inverter’s input window across all temperatures. Good string design also manages shade and multiple roof orientations to maximise output. It’s invisible, regulated, electrician-only work — but understanding it explains why panel layout matters and why a thoughtful installer designs the array around your specific roof and inverter.
Get a free assessment and we’ll design an array layout matched to your roof and inverter.
Sources: Series/parallel wiring, MPPT voltage-window, and string-design principles per AS/NZS 5033 and inverter manufacturer guidance; Standards NZ. Wiring is prescribed electrical work for a registered electrician.