In the latest years, some optimization technologies “at the module level” have established in the photovoltaic sector. These can be used both in existing plants, with the aim to improve the plant characteristic, e.g. in the case of partial shadows, and in new plants for additional features as monitoring or the possibility to increase performances.
Make the most of the energy captured by the MPPT function
An important task of the electronic part connected to the modules in a photovoltaic plant is to make the most of the captured energy by a function said MPPT (Maximum Power Point Traker). This function is usually performed by the inverter which can have one or more independent channels that can pursue that aim.
MPPT functions performed by the inverter
In the vast majority of the existing photovoltaic installations, the inverter performs the MPPT function and this is beneficial as the photovoltaic modules are as uniform as possible, exposed with the same inclination and orientation and without shading.
What to do in case of shading
In case of shading, or when photovoltaic modules are not always the same or are installed in different modes, it is convenient to evaluate optimization systems at the “module level”, which implement the MPPT function for each photovoltaic module.
Two type of “module-level” optimization
- Install the optimization devices in each photovoltaic module of the plant.
It gives the possibility to monitor every single photovoltaic module performances and make the plant more flexible also to future variations, as for example, to substitute a photovoltaic module with one with different characteristics.
- Install the devices connected only to the modules that are shaded or represent abnormal characteristics if compared to others.
The optimization which is affecting only some of the photovoltaic modules is generally preferable on performances improvement interventions in existing plants that probably were not properly designed, for example those were chimney shadows, trees and surrounding buildings were not taken into consideration.
MPPT: Maximum Power Point Traker
The MPPT is the functionality of a device to follow over time the voltage and power parameters of a photovoltaic module or of series of modules, a string, in order to get the maximum useful power moment for moment.