Vocab:
Recombination: An electron reconnects with a hole
Shunt: Low resistance path for electric current
Irradiance: Solar energy per area. Also called insolation.
What is an MPPT?
https://en.wikipedia.org/wiki/Maximum_power_point_tracking
https://www.solar-electric.com/learning-center/mppt-solar-charge-controllers.html/
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#:~:text=An%20MPPT%2C%20or%20maximum%20power,battery%20bank%20or%20utility%20grid.
The central problem addressed by MPPT is that the efficiency of power transfer from the solar cell depends on the amount of available sunlight, solar panel temperature and the load's electrical characteristics. As these conditions vary, the load characteristic that gives the highest power transfer changes. The system is optimized when the load characteristic changes to keep power transfer at highest efficiency. This optimal load characteristic is called the maximum power point (MPP). MPP Tracking is the process of adjusting the load characteristic as the conditions change. Circuits can be designed to present optimal loads to the photovoltaic cells and then convert the voltage, current, or frequency to suit other devices or systems.
An MPPT, or maximum power point tracker is an electronic DC to DC converter that optimizes the match between the solar array (PV panels), and the battery bank or utility grid.
How does an MPPT work?
For any given set of conditions, cells have a single operating point where the values of the current (I) and voltage (V) of the cell allow maximum power output.
A photovoltaic cell, for the majority of its useful curve, acts as a constant current source.However, at a photovoltaic cell's MPP region, its curve has an approximately inverse exponential relationship between current and voltage. From basic circuit theory, the power delivered to a device is optimized (MPP) where the derivative (graphically, the slope) dI/dV of the I-V curve is equal and opposite the I/V ratio (where dP/dV=0)and corresponds to the "knee" of the curve.
A load with resistance R=V/I equal to the reciprocal of this value draws the maximum power from the device. This is sometimes called the 'characteristic resistance' of the cell. This is a dynamic quantity that changes depending on the level of illumination, as well as other factors such as temperature and cell condition. Lower or higher resistance reduces power output. Maximum power point trackers utilize control circuits or logic to identify this point.
DC-DC Convertor:
About Solar Panels:
https://en.wikipedia.org/wiki/Maximum_power_point_tracking
How do Solar Panels work?
Fill Factor vs Efficiency:
The Fill Factor (FF) is essentially a measure of quality of the solar cell. It is calculated by comparing the maximum power to the theoretical power . FF can also be interpreted graphically as the ratio of the rectangular areas.
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A larger fill factor is desirable, and corresponds to an I-V sweep that is more square-like. Typical fill factors range from 0.5 to 0.82. Fill factor is also often represented as a percentage.
Cell efficiency refers to the portion of energy in the form of sunlight that can be converted via photovoltaic into electricity. Efficiency is the ratio of the electrical power output P(out,) compared to the solar power input, P(in), into the PV cell. P(out) can be taken to be P(max) since the solar cell can be operated up to its maximum power output to get the maximum efficiency.
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n(efficiency) = p(max)/p(input) = v(max)*i(max)/p(input).
n(efficiency) = p(max)/L*A , where L is the insolation of the cell in kw/m^2 and A is the area of the cell.
P(in) is taken as the product of the irradiance of the incident light, measured in W/m2 or in suns (1000 W/m^2), with the surface area of the solar cell [m^2].
Here’s a good video explaining solar optimizers: Note - optimizers are not always MPPTs, but the algorithm could be implemented on the optimizers. https://www.youtube.com/watch?v=E9NVLB_OYSU