PARALLEL CONNECTION OF SOLAR PANELS

PARALLEL CONNECTION OF SOLAR PANELS

21 mayo, 2019 Off By admin

Welcome to this informative page of Bitenergy.org. On this page we will show you how to connect several photovoltaic solar panels in parallel to obtain an increase in the available current at the output, keeping the nominal voltage unchanged.

PARALLEL CONNECTION OF SOLAR PANELS

In addition, we will explain the difference between a
parallel connection of two or more equal photovoltaic panels and a parallel connection of two or more photovoltaic panels with different technical characteristics.

How to connect solar panels in Paralrelo?

PARALLEL CONNECTION OF SOLAR PANELS

Welcome to this informative page of Bitenergy.org. On this page we will show you how to connect several photovoltaic solar panels in parallel to obtain an increase in the available current at the output, keeping the nominal voltage unchanged.

In addition, we will explain the difference between a
parallel connection of two or more equal photovoltaic panels and a parallel connection of two or more photovoltaic panels with different technical characteristics.

Finally, we will give you practical and useful tips to obtain a really efficient system and free of possible damages due to malfunctioning or
short circuits that could occur in the individual photovoltaic panels.
Ok, let’s start!

The connection of several solar panels in parallel arises from the need to reach certain values ​​of current in the output, without modifying its voltage. In fact, by connecting several photovoltaic panels in series we increase the voltage (maintaining the same current), while connecting them in
parallel we increase the current (maintaining the same voltage).

 

First of all, we should know that:

  • We connect solar panels in parallel to increase the current of the whole.  The voltage stays the same.
  • Voltage = Voltage.  Measured in Volts (V)
  • Current = Intensity.  It is measured in Amperes (A)

Parallel connection of two equal photovoltaic panels

PARALLEL CONNECTION OF SOLAR PANELSIf we have available two photovoltaic panels of the same voltage and power, the connection will be very simple. As you can see well in the following figure, it will be enough to connect the positive pole of one panel to the positive pole of the other and connect the negative pole of one panel to the negative pole of the other. In series, in each panel
we have introduced a blocking diode. Later we will discover the reason for these diodes.

This type of connection is really efficient if the following conditions are respected:
1) you place the panels very close to each other and oriented towards the Sun with the same angle
2) check that the panels do not shadow each other and that they are far from possible shading sources
3) you choose a timely section of the electric connection cable based on the distance from the panels
4) you use branch boxes to neatly connect the terminals of the panels to each other

What happens in case of shading?

First of all, it is good to know that the voltage that we find in the terminals of a shaded photovoltaic panel does not depend on the irradiation condition of the same, but rather on the load conditions to which it is subjected.

In fact, a shaded panel is still perfectly capable of receiving the
widespread share of solar energy and therefore can offer a positive working voltage of almost identical value when fully irradiated (it is the current capable of producing that is reduced proportionally to solar radiation).

It is understood then that in a photovoltaic plant on grid it is important the choice
of the photovoltaic inverter that will have the task of looking for the point of maximum power MPPT of the strip both in conditions of full radiation and in conditions of shading.

Parallel connection of two photovoltaic panels of different power

PARALLEL CONNECTION OF SOLAR PANELS

If we have available two photovoltaic panels of the same voltage but of different power, there is no problem; they can be connected quietly in parallel. If, on the other hand, the two photovoltaic panels are of different power and voltage, then the parallel connection is not possible, since the panel
with the lowest voltage would behave like a load, and would begin to absorb current, instead of produce it, with the respective consequences.

However, if we have a 12V panel and two 6V panels, then it is possible to connect the two 6V panels in series and then connect the series obtained in parallel to the 12V panel. This last type of connection, however, is detrimental to efficiency. Therefore, it is essential, before making a parallel connection, to check the voltage of the photovoltaic panels. Here you have a very clear picture of how two different panels should be connected in parallel.

Attention to the current!

You can connect several photovoltaic panels with this method, but you have to pay attention to the values ​​of the current. If your output value is higher than 70º, your panels and your plant can suffer damages and problems linked to the management of the current. To avoid this, the panels are usually connected in series-parallel,
to increase both the voltage and the current at the same time.

For example, if we had to connect six panels of 10A in parallel, we would have a very high current at the output, that is, 60A. To solve this problem and to optimize the energy efficiency of the entire plant, it is recommended to
connect two panels in series (thus obtaining twice the voltage) and then connect in parallel the three couples previously connected in series (to double the voltage and triple the current). In the figure below it is possible to see the scheme of this connection. This type of connection is frequently used for
plants of remarkable power.

To connect 3 24V solar panels in parallel

  • We connect the  wires +  of the 3 solar panels together. And the union is carried to the  + terminal  of the solar regulator.
  • We connect the  cables –  of the 3 solar panels together. And the union we take it to the  terminal –  of the solar regulator.

PARALLEL CONNECTION OF SOLAR PANELS

 

In the image above we can see the connection of 3 solar panels of 24V in parallel

  • The current  of the set is the sum of the current  Imp  of each solar panel: 5A + 5A + 5A = 15A
  • The  set voltage is equal to the voltage of each Vmp solar  panel : 24V

Important when connecting solar panels

  • Always connect the battery to the solar controller first and finally connect the solar panels.
  • Use solar regulators capable of withstanding the maximum charge current coming from the solar panels.
  • Calculate the load current using the  current at maximum power (Imp) . Do not use the short-circuit current (Isc).
  • Calculate the working voltage of the solar panels with the  voltage at maximum power (Vmp ). Not with the open circuit voltage (Voc).
  • The  open circuit voltage (Voc) is used to calculate the maximum voltage that the assembly can reach due to the temperature .