## Wednesday, August 30, 2023

Series, Parallel & Series-Parallel Connection of Solar Panels

What is a Solar Photovoltaic Array?

A Solar Photovoltaic Module is available in a range of 3 WP to 300 WP. But many times, we need power in a range from kW to MW. To achieve such a large power, we need to connect N-number of modules in series and parallel.

A String of PV Modules

When N-number of PV modules are connected in series. The entire string of series-connected modules is known as the PV module string. The modules are connected in series to increase the voltage in the system. The following figure shows a schematic of series, parallel and series parallel connected PV modules.

To increase the current N-number of PV modules are connected in parallel. Such a connection of modules in a series and parallel combination is known as “Solar Photovoltaic Array” or “PV Module Array”. A schematic of a solar PV module array connected in series-parallel configuration is shown in figure below.

The solar cell is a two-terminal device. One is positive (anode) and the other is negative (cathode). A solar cell arrangement is known as solar module or solar panel where solar panel arrangement is known as photovoltaic array.

It is important to note that with the increase in series and parallel connection of modules the power of the modules also gets added.

Series Connection of Modules

Sometimes the system voltage required for a power plant is much higher than what a single PV module can produce. In such cases, N-number of PV modules are connected in series to deliver the required voltage level. This series connection of the PV modules is similar to that of the connections of N-number of cells in a module to obtain the required voltage level. 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.

If a module has an open circuit voltage VOC1 of 20 V and another connected in series has VOC2 of 20 V, then the total open circuit of the string is the summation of two voltages

Calculation of the Number of Modules Required in Series and their Total Power

To calculate the number of PV modules to be connected in series, the required voltage of the PV array should be given. We will also see the total power generated by the PV array. Note that all the modules are identical having the same module parameters.

Step 1: Note the voltage requirement of the PV array

Since we have to connect N-number of modules in series we must know the required voltage from the PV array

PV array open-circuit voltage VOCA

PV array voltage at maximum power point VMA

Step 2: Note the parameters of PV module that is to be connected in the series string

PV module parameters like current and voltage at maximum power point and other parameters like VOC, ISC, and PM should also be noted.

Step 3: Calculate the number of modules to be connected in series

To calculate the number of modules “N” the total array voltage is divided by voltage of individual module, Since the PV module is supposed to be working under STC the ratio of array voltage at maximum power point VMA to module voltage at maximum power point VM is taken.

A similar calculation for open-circuit voltage of PV can also be done i.e. ratio of array voltage at open circuit VOCA to module voltage at open circuit VOC. Note that the value of “N” can be a non-integer so we have to take next higher integer and so the value of VMA and VOCA will also increase than what we desired.

Step 4: Calculating the total power of the PV array

The total power of the PV array is the summation of the maximum power of the individual modules connected in series. If PM is the maximum power of a single module and “N” is the number of modules connected in series, then the total power of the PV array PMA is N × PM.

We can also calculate the array power by the product of PV array voltage and current at maximum power point i.e.

Series, Parallel & Series-Parallel Connection of Solar Panels

What is a Solar Photovoltaic Array?

A Solar Photovoltaic Module is available in a range of 3 WP to 300 WP. But many times, we need power in a range from kW to MW. To achieve such a large power, we need to connect N-number of modules in series and parallel.

A String of PV Modules

When N-number of PV modules are connected in series. The entire string of series-connected modules is known as the PV module string. The modules are connected in series to increase the voltage in the system. The following figure shows a schematic of series, parallel and series parallel connected PV modules.

To increase the current N-number of PV modules are connected in parallel. Such a connection of modules in a series and parallel combination is known as “Solar Photovoltaic Array” or “PV Module Array”. A schematic of a solar PV module array connected in series-parallel configuration is shown in figure below.

The solar cell is a two-terminal device. One is positive (anode) and the other is negative (cathode). A solar cell arrangement is known as solar module or solar panel where solar panel arrangement is known as photovoltaic array.

It is important to note that with the increase in series and parallel connection of modules the power of the modules also gets added.

Series Connection of Modules

Sometimes the system voltage required for a power plant is much higher than what a single PV module can produce. In such cases, N-number of PV modules are connected in series to deliver the required voltage level. This series connection of the PV modules is similar to that of the connections of N-number of cells in a module to obtain the required voltage level. 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.

If a module has an open circuit voltage VOC1 of 20 V and another connected in series has VOC2 of 20 V, then the total open circuit of the string is the summation of two voltages

Calculation of the Number of Modules Required in Series and their Total Power

To calculate the number of PV modules to be connected in series, the required voltage of the PV array should be given. We will also see the total power generated by the PV array. Note that all the modules are identical having the same module parameters.

Step 1: Note the voltage requirement of the PV array

Since we have to connect N-number of modules in series we must know the required voltage from the PV array

PV array open-circuit voltage VOCA

PV array voltage at maximum power point VMA

Step 2: Note the parameters of PV module that is to be connected in the series string

PV module parameters like current and voltage at maximum power point and other parameters like VOC, ISC, and PM should also be noted.

Step 3: Calculate the number of modules to be connected in series

To calculate the number of modules “N” the total array voltage is divided by voltage of individual module, Since the PV module is supposed to be working under STC the ratio of array voltage at maximum power point VMA to module voltage at maximum power point VM is taken.

A similar calculation for open-circuit voltage of PV can also be done i.e. ratio of array voltage at open circuit VOCA to module voltage at open circuit VOC. Note that the value of “N” can be a non-integer so we have to take next higher integer and so the value of VMA and VOCA will also increase than what we desired.

Step 4: Calculating the total power of the PV array

The total power of the PV array is the summation of the maximum power of the individual modules connected in series. If PM is the maximum power of a single module and “N” is the number of modules connected in series, then the total power of the PV array PMA is N × PM.

We can also calculate the array power by the product of PV array voltage and current at maximum power point i.e.