Solar Array: What It Is and How to Size One

The panels are the part you see and the part everyone talks about. They're also perhaps a quarter of what makes a solar system work. Here's the whole thing.

What panels make up a solar array?

Modules of silicon cells wired in series, framed and sealed under glass. Their rated power is measured under standard test conditions, so it describes capacity rather than what you'll get on your roof.

Panels are wired into strings — series connections that build voltage — and strings connect in parallel to build current.

The key structural fact: in a series string, the weakest panel limits the string. That drives the shading problem and the case for module-level electronics. See how shading affects solar panels and solar panel specs explained.

Racking and mounting

The structural system holding panels at the right angle and attaching them to the roof or ground.

Its jobs:

• Carry the load — dead weight plus wind uplift and snow
• Penetrate the roof without leaking — flashing is the critical detail
• Maintain an air gap behind panels for cooling
• Bond the metal components electrically

Roof penetrations are where installation quality shows up over decades. See solar racking and mounting systems and roof suitability for solar.

What does a solar inverter do?

The component doing the actual conversion work: DC from the panels into AC at grid voltage and frequency.

It also:

• Tracks maximum power point — continuously adjusting to extract the most available power as conditions change
• Synchronizes with the grid
• Disconnects automatically if the grid goes down (anti-islanding) — see why solar shuts off in a blackout
• Reports production data for monitoring

Three architectures:

See string inverters vs microinverters and what is a power optimizer.

The inverter is the component most likely to be replaced during the system's life — panels commonly outlast it. Factor that into long-run economics. See how solar payback works.

Wiring, conduit and disconnects

Less glamorous, genuinely important:

DC wiring from panels to inverter, rated for outdoor exposure and the voltages involved.

AC wiring from inverter to the point of connection.

Disconnecting means so the system can be isolated for service and emergencies. Requirements come from the NEC and your utility's interconnection rules.

Rapid shutdown — a code requirement that roof conductors de-energize quickly on shutdown, so firefighters aren't facing live DC. Typically satisfied by module-level electronics. Your adopted edition governs.

Labeling and signage, which inspectors specifically check.

Grounding and bonding of all metal components — see grounding vs bonding.

How does a solar array connect to the house?

Where the solar system ties into your home's electrical system — commonly a breaker in the main panel, or a supply-side connection.

There are code limits on how much generation can be back-fed into a panel relative to its rating, which is why panel capacity sometimes constrains system size. If your panel is full or small, that's a real design input rather than an afterthought. See Electrical panel upgrade and check with the home electrical load calculator.

Metering

Your utility meter measures import and, on most modern meters, export separately.

A production meter may be required by your utility or program, measuring what the system generates regardless of where it goes.

What gets measured and how it's credited is the whole economic question. See net metering explained.

Monitoring

Software reporting production, usually at system level and — with module-level electronics — per panel.

This matters more than it sounds. A solar system can underperform silently for years; monitoring is how you notice. See solar panel monitoring explained and why is my solar production low.

Do you need a battery with a solar array?

Stores excess production for later use, and — with the right equipment — provides backup power during outages.

A battery system adds its own components: the battery itself, a battery inverter (or a hybrid inverter handling both), and typically a critical loads panel or transfer equipment.

See how home batteries work, hybrid inverters explained, and critical loads panel explained.

Balance of system

The trade term for everything that isn't panels: racking, inverters, wiring, conduit, disconnects, monitoring, labels.

It's a substantial share of both cost and labor, which is why:

• Systems aren't priced by panel count alone
• A small system isn't proportionally cheap — fixed costs don't scale down
• Site complexity matters — a simple south-facing roof plane costs less to install than three planes with obstructions

See what drives solar installation cost.

What components does a solar array need?

When reviewing a proposal, confirm it specifies:

• Panel model, quantity and rated output
• Inverter type, model and quantity
• Whether module-level electronics are included
• Racking system and roof attachment method
• Rapid shutdown compliance
• Monitoring platform and what it reports
• Connection method and any panel work required
• Warranties for panels, inverter, racking and workmanship separately
• Permits and interconnection handled

See choosing a solar installer and solar panel warranties explained.

The bottom line

An array is panels wired into strings, but a solar system is that plus racking that has to keep a roof watertight for decades, an inverter that does the conversion and will likely be replaced once, disconnects and rapid shutdown for safety, metering that determines the economics, and monitoring that's the only way you'll notice underperformance. Balance-of-system is most of the cost and most of the quality difference between installers.

Size a system with the solar panels needed calculator, estimate output with the solar output calculator, or read how do solar panels work.

Standards and code reference

The standards behind this guide, for looking up in the edition your jurisdiction has adopted:

• NEC Article 690 — PV system requirements
• NEC 690.12 — rapid shutdown of PV systems on buildings

Code editions and local amendments vary. Confirm the adopted edition with your AHJ, and treat manufacturer instructions as governing wherever they are more restrictive.