We have already published an article on this topic with the title Serial Connections in Solar Panels. In this article you can find detailed information and examples of the parallel circuit.
To begin with, you should know what paralleled connections are. In serial connections the voltage increases, whereas in parallel circuits the current value increases. This means that the solar cells of a parallel circuit have the same voltage but a higher current. What is important about the parallel circuit is that both of the solar panels have the same voltage output value; if this wasn't the case then there could be issues with the parallel circuit. We will discuss these below
Apart from a simple battery, using an additional protector on the solar panels will protect both our system and the panels. The main reason for that is that the solar panels not only generate electricity by virtue of its chemical construction, but it also consumes and exerts power.
The Mathematical Structure of Parallel circuits
We would like to give some basic information before a practical trial. First of all, suppose that the voltage of each solar panel generates is (V) and the current is (I), and we have two, identical solar panel cells.
Output Voltage = 12V
Output Current = 15A
Output Voltage = 12V
Output Current = 15A
When we shunt each of the solar panels:
Vtotal = V
Itotal = I1 + I2
To open this up;
Vtotal = 12V
Itotal = 30A
we have the above results.
Different Types of Solar Panels in Parallel Circuits
The above formula that we stated mathematically could be applied in a practical sense, but the solar cells have to be identical. How can we connect solar panels, whether identical or not, in parallel circuits?
Identical Solar Panels are Connected:
1.) After you carefully detect the (+) and (-) poles and,
2.) Implement both of the panels with the same angle to the sun and,
3.) Be careful that the solar panels are not be in each other's shadow and,
4.) Select the cable in accordance with the distance between the panels and,
5.) Shunt by connecting the same poles to each other.
The system is ready for use; you can use it by taking the mutual output connected at the top.
Different Solar Panels are Connected:
1.) By checking the output voltage of both of the solar panels.
2.) If they have the same voltage but different current, you can apply the above items.
3.) However, if they have different voltage values, there is not much you can do; you cannot shunt them.
Examples and Photos about Parallel Circuits
We have already said that voltage adaptation is the main rule for parallel circuits. When you have this adaptation, the circuits seen in the images below can be made.
The circuit made by using 2 solar panels
The circuit made by using 3 solar panels
The circuit made by using 4 solar panels
You can connect more solar panels using similar methods but you have to be cautious of the current. If your value is more than 70A, your solar panels and you system could be compromised. For this reason, by using both parallel and series circuits, you can increase both voltage and current simultaneously.
The thing to do in this point is to connect 2 or 4 panels in series and increase the voltage to 24V and 48V. The n shunt the units and increase the current values. Here are some examples:
Common connection with 4 solar cells
With the connection above, both voltage and current doubles and it becomes 2A and 2V.
Common connection with 6 solar cells
With the connection above the voltage value triples while current value doubles, becoming 3V and 2A.
With 8 solar panels
With the connection above the current value is four times higher and the voltage value is twice as high.
With 16 solar panels
In this connection both the voltage and current values have been increased by four times. These kinds of connections are used frequently. The 2V and 8A results for this connection can be obtained, but as mentioned before a high current is not necessary. We can have 3200W with 16 solar panels.
Advantages and Disadvantages of Parallel Circuits
- It helps control voltage while generating the system.
- It can only be used with the same voltage values
- It can cause a high current if there are too many connections.
Q: I have 3 solar panels that are of different brands but they have the same voltage value, can I shunt them?
A: If they have the same voltage values then you can connect them.
Q: Is the length of the cable important when connecting the solar cells?
A: The cables should be short enough and have the same length.
Q: I have 3 solar panels, 2 of which have a 6V output and 1 with a 12V output. How can I connect them?
A: The best thing to do is just to connect the 6V panels. If you think that efficiency is not that important, you can also use a series connection for the 6V panels and shunt them to a 12V panel.
Q: What kind of problems will I encounter if I shunted panels with 12V and 18V outputs?
A: If you connect this kind of a circuit, the system would work on the generator whose voltage is lower and the remainder will be lost through heat loss. For this reason the total voltage would be 12V.
Q: Is there any upper limit in a parallel circuit? Can I, for example, connect 40 solar cells?
A: It would not be a problem in theory but in practice there could be problems. First of all, the current would measure at least 400A which would cause an increasing loss on the conveying cables meaning you would need to use thicker cables. In addition to this, you have to make the system connections very carefully. Otherwise you would destroy the whole system.
Q: What is the parallel circuit efficient rate in solar cells?
A: Solar panels are not like standard batteries that have stable outputs. Therefore there will be a little lack of efficiency in any kind of circuits.
Q: I would like to shunt 16 panels in a way that they would be like 8 x 2. How thick a cable will I have to use?
A: If you imagine that each panel is 200W and 24V, the output current of the panels is 8A. With 8 shunts the total current would be 64A. For this reason you should use 20 – 30 mm section cables so that the circuit would remain safe.
Q: Do the panels in the parallel circuit face the same direction?
A: Definitely yes. If the panels faced different directions it would receive sunlight at different angles and this would cause extreme loss levels.
Q: Is a cross-connected connection a problem?
A: A cross-connection can cause short-circuit and therefore will obviously be a problem.
Q: What kind of a problem would arise if a panel in the parallel circuit solar panels fails?
A: It will not have a negative effect on the whole system but the system's total current value would decrease by as much as the failed panel. For this reason the failed panel should be replaced immediately.
This concludes the technical and practical details about this topic. If you have solar panels with different power and structure and you do not know how to connect them you can use this guide.