A Solar Photovoltaic Module is available in a range of 3 WP to 300 WP. But many times, we need powerin a range from kW to MW. To achieve such a large power, we need to connect N-number of module.
Thus the effect of parallel wiring is that the voltage stays the same while the amperage adds up. Photovoltaic solar panels generate a current when exposed to sunlight (irradiance) and we can increase the current output of an array by connecting the pv panels in parallel.
If the parallel connected pv panels are of different wattages and ratings, then both the voltage and current are limited to the lowest values, reducing the efficiency of the parallel connected array even at maximum irradiance. Voltage mismatch must be avoided in parallel connections.
The following figure shows solar panels connected in parallel configuration. If the current IM1 is the maximum power point current of one module and IM2 is the maximum power point current of other module then the total current of the parallel-connected module will be IM1 + IM2.
That is connecting solar panels in parallel increases the available current of the system, so two identical panels connected in parallel will produce double the current as compared to just one single panel. But while the currents add up, the panel voltage stays the same.
The following figure shows PV panels connected in series configuration. With this series connection, not only the voltage but also the power generated by the module also increases. To achieve this the negative terminal of one module is connected to the positive terminal of the other module.
In large PV plants first, the modules are connected in series known as “PV module string” to obtain the required voltage level. Then many such strings are connected in parallel to obtain the required current level for the system. The following figures shows the connection of modules in series and parallel.