Solar Panel
A module of photovoltaic cells encapsulated in a protective frame that converts sunlight to DC electricity — the visible component of a solar installation.
A solar panel (or solar module) consists of 60–72 photovoltaic cells wired together and laminated between protective glass and a polymer backsheet within an aluminum frame. Standard residential panels measure roughly 65 × 39 inches and produce 350–450 watts under Standard Test Conditions (STC: 1,000 W/m² irradiance, 25°C cell temperature).
Key panel specifications include watt-peak (Wp) rating, temperature coefficient (how much output drops per degree above 25°C — typically −0.3% to −0.5%/°C), degradation rate (quality panels degrade less than 0.5%/year), and product warranty (typically 12 years) versus performance warranty (typically 25 years guaranteeing at least 80% of rated output).
Panel count for a given system size depends on wattage per panel. A 10 kW system using 400W panels requires 25 panels. Installation quality — racking, wiring, shading avoidance — affects real-world output as much as panel brand.
Real-World Example
The homeowner chose 400W monocrystalline panels with a 0.35%/year degradation rate; after 25 years the panels would still produce at least 82% of their original rated output.