Off-grid wire configuration.. In this article, you will learn how to design a wiring configuration for an off-grid solar panel array. What I want my readers to do is to know how to combine various types of solar panel. Even regardless of size or manufacturer. So as to satisfy the needs of their solar charge controller.
Recall that charge controllers have specified working voltages for it’s input and the output. Manufacturers rate solar charge controllers in amps. Therefore, if you’re designing an entire system from scratch.
You should consider the charge and discharge rate of your battery. Also, you can check out my other blogs here. In this article we’re just going to learn how to satisfy the needs of the solar charge controller circuit. So let’s get started first.
HOW TO DESIGN SOLAR PANEL ARRAY | OFF-GRID WIRE CONFIGURATION
There are four variables that you must know to make this as simple as possible. These variables include:
- The battery bank nominal voltage: let’s say 24V
- The maximum PV input voltage VOC: Let’s say 150V
- The charge controller’s current capacity: Let’s say 60A
- The maximum input wattage from solar panel array to the charge controller
If you know these four variables, you should be able to design a wiring configuration with any type of solar panel.
The battery bank nominal voltage: Off-grid wire configuration
This is simply your battery bank nominal voltage. It must correspond with the range on the charge controller data sheet.
Let’s say your charge controller can handle 12V/ 24V/ 36V / 48V from the battery terminal.
In this article, we take 24V as the nominal voltage.
The maximum PV open circuit voltage VOC:
This is the maximum open circuit voltage your charge controller can accept from the solar panel array. If you exceed the maximum value, your charge controller will start to malfunction.
You can find the VOC voltage on the charge controller datasheet or typically it’s written on the back. Let’s say this one has it as 150V open circuit VOC.
The charge controller’s current capacity: Off-grid wire configuration
This is the maximum current the charge controller can withstand. It is often written boldly on the charge controller. Likewise, you can see it on the datasheet as well.
On no account should you exceed this current rating. Otherwise, the charge controller will damage.
We assume a 60Amp charge controller in this article.
The maximum input wattage from solar panel array to the charge controller:
The last but not the least variable is the maximum PV input wattage. This is variable to the battery bank nominal. Because you can find it by multiplying the battery bank nominal voltage by the charge controller current capacity.
For instance, the maximum PV input wattage here = 24 x 60. Therefore, Maximum PV input wattage = 1440 watts.
HOW TO DESIGN SOLAR PANEL ARRAY
Considering the 150V maximum PV input voltage as seen on the charge controller datasheet. I can tell you that we shall connect the solar panels in series.
The image above is a single solar panel datasheet. To know the exact number of solar panels you will connect in series. We first consider the maximum PV input voltage as stated on the charge controller labes as 150V.
Secondly, we consider the solar panel open circuit voltage VOC. The above image have as 44.5 VOC.
Therefore, to achieve the maximum open circuit voltage value that is slightly below 150V. We will connect some solar panels in series. This is because no single solar panel generates such a open circuit voltage.
Also, you can visit here to know more on how to measure open circuit voltage with a multimeter.
So let’s try to figure out the number of solar panels we can combine to create this 150volt open circuit. And while still satisfying this wattage rating.
Hence, let’s say I go on the internet and find a good deal on 80-watt solar panels. And each one produces 44.5V open circuit. let’s say I string these panels 3 in series.
This series connection adds up the system voltage to give 133.5 Volt. Your charge controller can comfortably withstand this voltage.
HOW TO DESIGN SOLAR PANEL ARRAY
Furthermore, to determine the total number of solar to make up a perfect array for your charge controller. Then we consider the maximum input power we calculated initially as 1440watts.
Mathematically 1440W/80W = 18 panels
In other not to overload the charge controller, I advise you reduce the number to 15 panels.
Therefore, we can divide our solar panel into five to give 3 panels each. Each of the 3 panels are connected in series. After which, we connect all the five different circuit in parallel to make up a full solar panel array.
SUMMARY | OFF-GRID WIRE CONFIGURATION
To summarize, we have achieve our target. Which is to know the number of solar panels we wire in series and parallel configuration.
If you disagree and you think I missed something please let me know in the comments section below and I will see you in the next article thank you bye.
