Measurement
Power density is the amount of power (typically measured in watts) generated or consumed per unit area (or volume). In renewable energy, power density can refer to how much power a solar installation generates per square meter of land or panel surface, or how much power a battery can deliver per liter of volume. Higher power density means more power output from a smaller footprint. For instance, solar panels have a certain power density (watts per square meter under sunlight), and different energy sources have varying power densities (e.g., fossil fuels have high power density in terms of energy content by weight, whereas solar and wind are lower, which affects land use). In battery technology, improving power density means the battery can deliver more instantaneous power without increasing size.