Importance of Module Mismatching

Module Mismatching

When PV modules are connected in series,  there is something known as “the Christmas light effect”.

If one module has less current, then it eventually limits the amount of current to flow through the whole series-connected PV source circuit (string).

Before there were bypass diodes in PV modules when a cell was shaded all of the currents from all of the other cells and modules would try to push through the shaded cell. This would create heat (from resistance) and could be a fire hazard also hindering with performance capabilities.

Mismatch losses usually occur due to interconnection of solar cells or modules which do not have identical properties. Such losses pose a serious problem in PV modules and arrays under certain conditions as the output of the entire PV module under worst case conditions is determined by the solar cell with the lowest output. For example, when one solar cell is shaded while the remaining modules are not, the power being generated by the “good” solar cells are easily dissipated by the lower performance cell rather than powering the load.

Other factors affecting this mismatch:

• the operating point of the PV module;
• the circuit configuration; and
• the parameter (or parameters) which are different from the remainder of the solar cells.

                        <figure>
                                    <img width="436" height="249" src="https://dcsgroups.in/temp/wp-content/uploads/2020/08/Screen-Shot-2020-08-20-at-12.06.51-PM.png" alt="" srcset="https://i2.wp.com/www.firstgreen.co/wp-content/uploads/2020/08/Screen-Shot-2020-08-20-at-12.06.51-PM.png?w=436&amp;ssl=1 436w, https://i2.wp.com/www.firstgreen.co/wp-content/uploads/2020/08/Screen-Shot-2020-08-20-at-12.06.51-PM.png?resize=286%2C163&amp;ssl=1 286w, https://i2.wp.com/www.firstgreen.co/wp-content/uploads/2020/08/Screen-Shot-2020-08-20-at-12.06.51-PM.png?resize=218%2C124&amp;ssl=1 218w, https://i2.wp.com/www.firstgreen.co/wp-content/uploads/2020/08/Screen-Shot-2020-08-20-at-12.06.51-PM.png?resize=150%2C86&amp;ssl=1 150w" sizes="(max-width: 436px) 100vw, 436px" />                                            <figcaption>These modules in series give 7A</figcaption>
                                    </figure>