A solar panel (also called a photovoltaic or “PV” panel) is essentially a flat module made up of many small solar cells.
Specifications
Power (Pmax / Wp)
The peak DC output the panel can produce under ideal conditions (sunlight, temperature, etc.) — basically the panel’s rated wattage.
~ 250 W to ~ 400 W for many residential panels; some panels go higher.
Efficiency (%)
The fraction of sunlight the panel converts into electricity (how “good” it is at converting solar energy). Higher efficiency = more power in less space.
Commonly ~ 15%–23%.
Voltage at Max Power (Vmp)
The DC voltage output when the panel is operating at its most efficient point (i.e. generating Pmax). Important for matching with inverters or charge controllers.
Varies per panel — e.g. for a small 100 W panel, Vmp might be ~ 18.5 V.
Current at Max Power (Imp)
The DC current output (Amps) when the panel is delivering max power. Useful for calculating energy output and for wiring/cabling design.
Depends on the panel size/power — varies widely.
Open‑Circuit Voltage (Voc)
Voltage measured when panel terminals are open (no load). Gives a maximum voltage threshold when designing string/array.
Panel‑specific, but significantly higher than Vmp.
Short‑Circuit Current (Isc)
Current when panel terminals are shorted (zero load). Helps estimate current carrying/wiring needs.
Panel‑specific.
Temperature Coefficient
Shows how panel performance changes with temperature. Since solar panels heat up under sun, power output often drops with higher temperature — this tells you how much.
Typical coefficient may be around –0.3% to –0.5% per °C (varies with panel type).
Panel Dimensions & Weight
Physical size and mass — important for installation (roof space, mounting structure, handling).
Example: a small 100 W panel might be ~ 944 mm × 674 mm × 30 mm, weight ~ 7–8 kg.
Durability / Environmental Specs
Operating temperature range, frame/glass durability, weather/water resistance, expected lifespan, warranties.
