That may depend on various properties of the cell material, design, and physical principles behind the conversion process. When we talk about the performance of a particular solar energy conversion device (for example, a solar cell), power density characterizes the "quality" of the energy conversion - how much power is generated by each square meter of the cell area.
There is an important distinction between the total power (measured in W) and power density or flux (measured in W/m 2). We will get back to those considerations when talking about specific conversion technologies in detail in respective lessons of this course. The origin of those losses can be a complex issue, which could be better understood based on the physics and design of a particular conversion device – PV cell, concentrator, or thermal collector. The reason that energy conversion systems have less than 100% efficiency is that there are losses. Then, for efficiency, we can write: η = P out / P in = 112.5 / 1000 ×100% = 11.25%Ĭonclusion: only 11.25% of energy flowing to the panel is converted to electricity. Identifying power output from the PV cell: P out = E × I / Area = 112.5 W/m 2 (Note: from physics, power is equal voltage times current) Identifying power input to the PV cell: P in = S =1000 W/m 2 Standard solar input (irradiance) at the module surface: S = 1000 W/m 2 Generally, to estimate the efficiency of solar energy conversion, you would need:Ĭonsider the example below, which shows estimation of the standard efficiency of a PV module. If we have solar irradiance measured and device performance data collected, we can tell at what efficiency the system operates. When the exterior conditions are kept constant, measured efficiency is solely a device characteristic. Panel oriented perpendicular to the light beam.Photovoltaic cells are compared by nominal efficiency measured at standard conditions : What fraction of available energy is lost in the conversion.Η = P o u t P i n × 100 % What can we learn from efficiency analysis? When applied to solar energy conversion systems, efficiency of solar energy conversion (η) is defined as the ratio of the useful output power (delivered by the conversion device) to the incident power (of the solar radiation): We see that efficiency of conversion η is an important metric of system performance.
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