Solar Panel Parameters
Following are some of the key parameters associated with solar panels worth studying.
Power output (P): It is the maximum power that the solar panel can generate. This specification is measured in watts (W).
Voltage (V): It is the potential difference generated between the positive and negative terminals of the solar panel. This specification is measured in volts (V).
Current (I): The flow of electrical charge through the solar panel is termed as the current (I). This specification measured in amperes (A).
Open circuit voltage (Voc): This is the maximum voltage that the solar panel can generate while it is not connected to any form of load across its positive and negative terminals.
Short circuit current (Isc): This is the maximum current that the solar panel can generate while its positive and negative terminals are shorted, or connected across each other.
Fill factor (FF): This is a measure of the efficiency of the solar panel. It is defined as the ratio of the maximum power that the solar panel can produce to the product of its open circuit voltage and short circuit current. FF = P / Voc x Isc
Temperature coefficient (TC): This is a quantity which indicates how the output voltage and current of the solar panel change depending on the changes in ambient temperature or the solar panel temperature.
Efficiency: This is a magnitude which indicates the percentage of solar energy that the solar panel can practically convert into electrical energy.
These parameters are important for selecting and designing solar panel systems, as well as for evaluating their performance.
How to Connect Solar Panels in Series and Parallel
Connecting solar panels in series and parallel are two common methods for increasing the voltage and current of a solar panel array.
When you connect solar panels in series, you connect the positive terminal of one solar panel to the negative (-) terminal of another solar panel. The total voltage of the array will be the sum of the voltages of each solar panel, while the current will be the same as that of the solar panel having the lowest current specifications.
When you connect solar panels in parallel, you connect the positive terminals of all the solar panels together and the negative (-) terminals together. The total voltage of the array will be the same as that of a single solar panel, while the current will be the sum of the currents of each solar panel.
The following are the formulas which can be used to calculate the total voltage and current for solar panels connected in series and parallel:
Formula for Calculating Solar panels connected in parallel:
Total Voltage = V1 = V2 = V3 = … = Vn, where V1, V2, V3, … Vn are the voltages of each solar panel.
Total Current = I1 I2 I3 … In, where I1, I2, I3, … In are the currents of each solar panel.
Please note that when solar panels are connected in series, the total voltage of the array will increase, but the total current will remain the same as that of the lowest current solar panel. When solar panels are connected in parallel, the total current of the array will increase, but the total voltage will remain the same as that of a single solar panel.
What is a Series Circuit?
A circuit is joined in series when the same, single current (amp) runs through every component in the circuit. In these circuits, the current has just one course.
Let’s take the household decorative string lights as an example. It is simply a series of many small light bulbs attached in series. If a single light bulb fuses, all the bulbs in series configuration fail to light up.
What is a Parallel Circuit?
A circuit is considered parallel when the electric current has several paths it flows through. The components that make up the parallel circuits have an unbroken voltage flow through all ends.
The main difference concerning series and the parallel circuit is the amount of current that runs through every component in the circuit.
In the series circuits, the same quantity of current runs through all components positioned in it. Alternatively, in parallel circuits, the components are positioned in parallel with each other, and because of this, the circuit splits the current flow. The current flowing from the source will be distributed into the current running through each of these components.
Note, however, the amount of current does get divided according to total resistance (measured in ohm) of EACH parallel branch. It then adds back up when the current is flowing back into the power source.
Difference Between Series and Parallel Circuits [Table]
I’d advise making your circuit diagram on a white paper first before you go on building it. A simple electrical circuit contains a single battery, a light bulb and a few connecting wires.
Other advanced ones could include many light bulbs, motors, resistors and battery bank (with parallel battery connection).
Wiring in Series Example
Wiring RV solar panels in series is the cheaper and more flexible option. Higher voltage rather than amperage means that you will have smaller wires and more resiliency in different shading scenarios.
You can envision it like stringing up several panels in a row to make one big panel.
In this example, 3x100W solar panels with 18 volts and 6 amps of power are wired in series.
This gives you a total of 54 volts and 6 amps of power.
Wiring in Parallel Example
Wiring solar panels in parallel can be more intuitive (all red wires together, all black wires together). This is a good choice if your other solar components can’t handle high voltage. For example, if your charge controller is only limited to 24V input, you wouldn’t want to series wire panels to give 48V input.
In this example, 3x100W solar panels with 18 volts and 6 amps of power are wired in parallel.
This gives you a total of 18 volts and 18 amps of power.
Shade Conditions
On overcast days, or in low-light situations, series wiring is the best. This is because if a single panel is shaded it doesn’t limit the voltage of the whole string. You still get the full output of the rest of the panels.
It can also make use of very little sun because each panel’s voltage is added together, making it more likely to meet the minimum voltage needed to charge your batteries.
If you use parallel wiring, then any panel that’s in the shade will limit the overall electricity output.
Wire Size
Parallel solar needs bigger wiring, fuses, and combiners. Each panel must be fused at the combiner junction in case one shorts out. The wiring must be bigger as you are increasing amps.
If you use an MPPT charge controller, it’s best to wire your solar panels in series to get the highest voltage the controller can accept. This will provide the highest voltage possible and ensure the most efficient charging of your batteries.
However, if you’re using a PWM charge controller, then parallel wiring is recommended as it will provide the highest current possible.
Series. Parallel connection of solar panels
What is the series and parallel connection of solar panels?
Generally, the solar panel array will be affected by many factors, especially the charging controller used. The design of the charging controller only accepts a certain amount of current intensity and voltage. For larger solar energy systems, the series-parallel connection design must be adopted at the same time to maximize the power of the solar energy system. We must keep the current and voltage within the appropriate range for this creative connection. Similarly, take a simple example:
- In the above figure, 4 x 100w panels, each with a rated voltage of 17.9V and a current of 5.72A
- The first pair of panels in the series can produce 35.8 volts and 5.72 amps.
- The second pair of panels in the series can produce 35.8 volts and 5.72 amps.
- The two lamp strings in parallel can produce a voltage of 35.8 volts and a current of 11.44 amperes. 409 watts in total.
When the solar panels in the array are identical, no matter how they are wired (at least mathematically), the power output is the same, but the current and voltage are different.
What conditions are solar panels connected in series-parallel?
As mentioned above, when your solar system is extensive, it is not most effective to use solar panels only by using a series or parallel connection. In reality, it is a standard method to connect multiple solar cells in series and parallel, which can make the current and voltage critical balance, thus giving full play to the best performance of the solar system.
At this time, the series connection will increase the voltage, allowing you to use smaller wires. Your MPPT charging controller will be more effective and valuable. The parallel connection will increase the current, requiring larger wires, which can prevent the power generation efficiency of the solar panel from being affected due to insufficient light intensity.
In a word, no matter how you connect multiple solar panels, the simple considerations can be summarized as voltage, current, and the size of the solar system. Suppose you encounter problems during the connection process. In that case, you must seek professional help, and the best advice, and BougeRV’s after-sales team will continue to help.
What is the difference between series and parallel solar panels?
Let’s imagine a scene: the Christmas lights in the Christmas tree suddenly have a bulb burned out for some reason, and the whole string of lights will not light up at this time. This is because these lights are connected in series. You must find the defective bulb and replace it.
However, today’s Christmas lights are all connected in parallel, which means that even if one is broken, other bulbs can work as usual. This is the parallel connection method.
If one panel in a series fails, the entire circuit will fail. In contrast, the defective solar panels in parallel will not affect the output of other solar panels.
Another essential thing to remember is that connecting solar panels in series will increase the voltage. In contrast, the parallel connection will increase the current. When designing a solar system, professionals will consider the voltage, current, system size, and the inverter most suitable for you.
In most cases, professional solar installers will design a system shared in series and parallel, enabling the system to generate power at the most appropriate voltage and current so as not to overload the inverter so that your solar charging panel can output power at the best state.
Should your solar panels be connected in series or in parallel?
The choice of series connection or parallel connection for your solar charging panel mainly depends on the demand of your electrical equipment and the surrounding environment. For general ships and RVs, the parallel connection of solar charging panels can provide more efficient wiring and public voltage.
However, for large applications with a power of more than 3000w, it may be better to use the series connection mode to obtain higher voltage. Before choosing, you should understand the operating conditions and working principles of various wiring devices to ensure that you determine the most appropriate way and confidently install the solar charging panel.
If your solar charging panel is not covered by shadows most of the time, connecting multiple solar panels in series will be your first choice. This will make your solar charging panel system more efficient and perform better in the daytime and on cloudy days.
In a word, there is no solution for everyone. There should be a corresponding solution for specific problems and conditions. If you are unsure how many shadows your panel will receive, consider using the parallel method. Of course, you can also communicate with the after-sales team of bougeRV, and we will do our best to help you.
Suggestions for efficient use of solar charging panels
Pay attention to any object on the roof that may cast shadows on the panel, such as an antenna, satellite, vent, etc.
In the whole solar system, use solar panels of the exact specification as much as possible.
Using a hybrid panel. you can connect them in series through appropriate wires to configure the maximum current.
Remove the damaged panels in the solar system to avoid affecting the power output of other boards.
Make the specifications of the solar panels as close as possible. Don’t put panels with significant differences in specifications together for use. For example, put 50w 3A 18v and 200w 9A 21v together.
When the RV uses the solar energy system. it usually adopts the series connection method.
Avoid parking your RV in an utterly fantastic place to maximize the solar system’s efficiency.
How does a series solar panel connection work?
Let’s take a look at how we can connect some solar panels in a series circuit.
We’ll use an example of a series circuit connecting four 100 Watt solar panels. Each solar panel is 20 Volts and 5 Amps.
The circuit is formed by connecting the positive electrical terminal of one solar panel to the negative terminal of the next in a line and running a cable from each end of this line to the other components of our solar system. We can calculate the voltage current and power of this circuit as follows.
Total voltage = 20 Volts x 4 = 80 Volts
Total current = 5 Amps
Total power = 80 Volts x 5 Amps = 400 Watts
How does a parallel solar panel connection work?
When we take these same four solar panels and connect them in a parallel circuit, we run the cables from each panel separately into our solar system. We don’t join any of the solar panels together. We’ll see why this is important in a little while. This is what the voltage, current, and power of our parallel solar panel connection look like.
Total voltage = 20 Volts
Total current = 5 Amps x 4 = 20 Amps
Total power = 20 Volts x 20 Amps = 400 Watts
Even though the voltage and amperage of our series and parallel solar connections are very different, you can see that the final power output is the same.
So we’ve proved that there is no difference in the power output from a series or a parallel solar system when the voltage and amperage of all solar panels are the same. But things get complicated when you wire together panels with different voltage and amperage capacities.
Series Vs Parallel (Solar Panel Wiring Comparison). EP10 Van Build
The effect of mixing solar panels in serial and parallel connections
Now let’s make the same circuits with three 100 Watt solar panels of 20 Volts and 5 Amps and another 75 Watt panel of 25 Volts and 3 Amps. This is the total power of 375 Watts.
The difference here is that when you wire different solar panels in series, you need to use the lowest amp rating of all the panels.
Serial Connection
Total voltage = 20 Volts x 3 25 Volts x 1 = 85 Volts
Total current = 3 Amps (taking the lowest rating)
Total power = 85 Volts x 3 Amps = 255 Watts
Because we had to use the lowest amperage panel for the series connection, we ended up with a total power output of 255 Watts, resulting in a loss of 375 – 255 = 120 Watts of power.
Now, when you wire the same panels in a parallel connection, you need to use the lowest voltage.
Parallel Connection
Total voltage = 20 Volts (taking the lowest rating)
Series VS Parallel! A Beginner’s Guide for Solar Panel Connections. With Basic Diagrams!
Total current = 5 Amps x 3 3 Amps x 1 = 18 Amps
Total power = 20 Volts x 18 Amps = 360 Watts
When using the panel with the lowest voltage for the parallel connection, we ended up with a total power output of 360 Watts, resulting in a loss of 375 – 360 = 15 Watts.
If you’re not careful when wiring solar panels of different capacities, you can lose a lot of power. In these situations, it’s essential to look at the ratings and calculate the effects of serial or parallel wiring. But there are also some other advantages and disadvantages of these wiring systems that you need to take into account.
Advantages and disadvantages of series and parallel wiring systems
Wiring
If you are running an electrical circuit with high amperage, you need a thick cable to carry the load. Think back to the water example, where you’d need a strong pipe to handle a powerful flow of water.
Wiring your solar panels in parallel means that you need cabling and components rated for high Amperage. If you use serial wiring for your solar system, there will be a higher voltage and low amperage, reducing the demands on your cables and components. If you’re uncertain about which wire size to choose for your solar setup, you might find our article on how to choose solar wire size.
The main benefit of parallel wiring
When you wire all your solar panels in parallel, the performance of one panel is not dependent on the performance of the other panels. But in a serial connection, if one solar panel is working at a lower capacity, it reduces the whole solar array’s performance.
This is important in case a panel in a series connection malfunctions. Also, if a particular panel in the series may be receiving less sunlight because of shade, the whole system’s power output will be reduced.
Summary
Now you have a good idea about the differences between serial and parallel wiring systems. Each has its benefits and drawbacks, and you’ll need to think carefully about which one to use.
If you plan to connect solar panels of different capacities, then a parallel connection is probably best. Parallel connections will help you avoid an underperforming solar panel lowering the output of your whole system.
But remember, depending on your specific system requirements and the specifications of your panels, it may be more complicated and potentially more expensive to wire and connect your solar panel system in parallel.
Perhaps one solution is to carefully check the placement and performance of your solar panels so that if you choose to wire them in series, you can minimize the risks of performance loss.
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