Yash
The output of solar panels is matched with the solar inverter input through series and parallel combinations of the solar panels.
The solar panels absorb the sunlight and convert it into electricity. This electric current goes inside the solar inverter and it converts it into alternating current.
The solar inverter does not take any value from the solar panels.
The solar panels’ output must be in the solar inverter’s operational range.
Every inverter has a specific input DC voltage range.
If the solar panels produce a voltage in this range, only then the solar inverter will take it and process it further.
Therefore, we need to arrange and connect the solar panels array in a way that they produce voltage in the input range of the solar inverter.
An example of grid-tied solar power system
Assuming, I have a 5-kW grid-tied solar power system. It is connected to the 5 kVA solar inverter to convert the DC into alternating current. running the electrical appliances.
The input voltage range of 5 kVA solar inverter is 120 volts to 600 volts.
On the other hand, I have 10 x 500 watts solar panels each with a Vmp of 45 volts and an Imp of 11.11 amperes.
(Vmp = voltage at maximum power; Imp = current at maximum power).
I need to connect the solar panels in a way (series, parallel, or a combination of both) that they produce the resultant voltage in the input range of the solar inverter.
Before that let us understand the concept of series and parallel combinations.
Series combination of the solar panels
In a series combination, the positive terminal of one solar panel is connected to the negative of another.
This combination is also called head-to-tail connections as the positive of one solar panel is connected to the negative of another solar panel.
In series combination, the voltage of the individual solar panels adds up while the current remains the same.
Assuming 3 solar panels of Vmp 45 volts and Imp of 11.11 amperes each are connected in series. This makes a system of 3 solar panels in series.
In this system, the Vmp of each solar panel adds up while the current remains the same.
The system voltage will become 45 volts x 3 = 135 volts
The system current would be the same as that of individual solar panels which is 11.11 amperes.
Parallel combination of solar panels
In this combination, the positive terminals of the solar panels are connected and the negative are connected.
In parallel combination, the current of the individual solar panels adds up while the voltage remains the same.
In the above parallel system of the three solar panels, the voltage will remain the same as that of an individual solar panel.
While the current adds up to 11.11 + 11.11 + 11.11 = 33.33 amperes.
Coming back to the example
I have 10 x 500 watts solar panels with each having Vmp of 45 volts and Imp of 11.11 amperes.
(Power is the product of voltage and current. I can write it mathematically as:
P(max) = Vmp x Imp
We need to connect these ten solar panels in a way that they produce a voltage in the acceptable range of the solar inverter which is 120 volts to 600 volts.
Let us do it with hit and trial basis.
One string of solar panels
First, connect all the solar panels in series.
See the picture below of a system of ten solar panels connected in series.
In series, the individual Vmp of the ten solar panels will add up while keeping the system current the same as that of individual solar panels.
The system voltage becomes 45 volts x 10 = 450 volts while the system current remains 11.11 amperes.
Does 450 volts come in the acceptable range of the solar inverter?
Yes, it is in the input range of our inverter. The solar inverter will readily accept it and process it further for running the electrical appliances.
Two strings of solar panels
Let us try another combination which I have called a 2-string system.
Please see the picture below.
It is a system of 2-strings of solar panels.
Each string has 5 solar panels connected in series.
Further, these 2 strings are connected in parallel to each other.
Let us name the strings as string 1 and string 2.
For string 1, the five solar panels are connected in series. Therefore, the individual voltage adds up. This will make the string 1 voltage as 45 volts x 5 = 225 volts. The current will remain the same as 11.11 amperes.
Similarly, for the string 2, the voltages of five solar panels add up and current remains the same. Thus, making the string values same as string 1 which are 135 volts and 11.11 amperes current.
Now, these two strings are connected in parallel. Therefore, the current from each string combines 11.11 amp + 11.11 amp, making it a total system current of 22.22 amperes.
While the system voltage will be voltage of each string that is 225 volts.
The final values of this two-string system of solar panels are 225 volts and 22.22 amperes.
Does 225 volts fall in the input range of the solar inverter?
Yes, it falls in the acceptable range of the solar inverter. Therefore, the solar inverter will take this DC voltage, convert it into alternating value, and feed it to the electrical appliances.
This is how we do the arrangement of the solar panels so that their output falls in the acceptable range of the solar inverter.
Conclusion
- The right arrangement of the solar panels is important so that their output voltage falls in the input voltage range of the solar inverter.
- This arrangement could be in series, parallel, or a combination of both.
- In series, the voltage adds up while the current remains the same.
- In parallel, the current adds up and the voltage remains the same.
- P(max) = Vmp x Imp
