How Do Solar Panels Actually Work?

Solar panels can seem like a black box — sunlight goes in, electricity comes out. Here's what's actually happening, explained simply.

The Photovoltaic Effect

Solar panels are made of photovoltaic (PV) cells, typically silicon-based. When sunlight (photons) hits these cells, it knocks electrons loose from their atoms, creating an electric current. This is called the photovoltaic effect, and it's a purely electronic process — no moving parts, no combustion, no fluids.

From Panel to Power Outlet

1. Panels generate DC power: Sunlight hitting your panels produces direct current (DC) electricity.
2. The inverter converts it: Your home's outlets and appliances run on alternating current (AC), so an inverter converts the DC output from your panels into usable AC power.
3. Power flows to your home first: The AC electricity flows into your home's electrical panel and powers your appliances directly.
4. Excess power goes to the grid: Any power you generate beyond what you're using gets sent back to the grid, and depending on your net metering agreement, you receive a credit.
5. You draw from the grid at night: Since panels don't produce power after dark, you draw electricity from the grid as usual overnight, offset by the credits you built up during the day.

Types of Solar Panels

Monocrystalline: Made from a single silicon crystal, these are the most efficient and most common residential choice, typically 20-22% efficient.

Polycrystalline: Made from multiple silicon fragments melted together, slightly less efficient (15-17%) and typically less expensive.

Thin-film: Flexible and lightweight but lower efficiency (10-13%), used in specialized applications rather than typical residential roofs.

What Affects How Much Power You Generate

• Sun hours: More direct sunlight hours per day means more production. This varies significantly by region.
• Panel orientation: South-facing panels (in the Northern Hemisphere) typically produce the most power.
• Shading: Even partial shading on one panel can significantly reduce output for that panel and sometimes an entire string.
• Temperature: Counterintuitively, panels lose some efficiency in extreme heat — cooler sunny days can actually produce more power than very hot ones.