Final Thoughts: Series Vs Parallel Which Is Better For Solar Arrays
When it comes to installing solar arrays on houses, the answer is more clear. Because there are more panels involved, wiring solar panels together in series provides more upside. You can keep wire thickness sizes to a minimum and you dont have to worry about those pesky fuses.
But when it comes to wiring a much smaller solar array on a mobile vehicle, we think the answer becomes less clear.
In the end, the decision is up to each of us. Do we value wiring simplicity? Do we value maximizing production in partial shading situations?
We hope that by the time youve reached the end of this post, you have a greater idea of what type of wiring is best for your own solar array system.
Does Wattage Increase In Series
In a world where technology is constantly evolving, its hard to keep up with the latest trends. One such trend is the wattage race: manufacturers are constantly releasing products with higher and higher wattages. But does wattage increase in series?
To answer this question, we first need to understand what wattage is. Wattage, which is measured in watts, is the amount of power that a device consumes. Its determined by multiplying voltage by current. So, if you have two devices with the same voltage but different currents, the device with the higher current will consume more watts.
Now that we know what wattage is, lets look at whether it increases in series. In theory, it should after all, if you have two devices with the same voltage but a different electrical current, wouldnt they consume more watts if they were connected in series?
How Does The Back Of A Solar Panel Look
If you look at the flipside of a solar panel, you will see a black box and two cables coming out of this box. The black box is called a junction box and there is one positive and one negative cable coming from this box. The junction box is IP 65 rated. The cables are single core copper with a cross section of 4mm2. You will find MC4 connectors used at the terminals of the cables.
How you connect these cables determines if itâs a series or parallel connection.
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How Parallel Connections Affect Volts & Amps
In a parallel connection, the amps generated by each panel get added together. But the voltage stays the same.
Therefore, if you have three solar panels that can each output a maximum 18.8V and 5.86A, then the solar array has a potential to generate only 18 volts but 17.58 amps of current.
The fancy math: 5.86 amps x 3 panels = 17.58 amps
Connect The Cables To The Y Branch Connectors
These are Y branch connectors:
Theyre used for wiring 2 solar panels in parallel. Youll need to get a pair to complete these steps.
Connect the 2 positive solar panel cables to the compatible Y connector. This will likely be the FFM connector.
Then connect the 2 negative solar panel cables to the other Y connector. This will likely be the MMF connector.
Note: If using MC4 inline fuses, connect them between the each positive cable and the Y connector.
Done! The 2 solar panels are now wired in parallel.
Need to wire more than 2 solar panels in parallel? Simple just get the right size branch connector.
For example, if wiring 3 solar panels in parallel, use a pair of 3 to 1 branch connectors.
And if wiring 4 solar panels in parallel, use 4 to 1 branch connectors.
Note: When wiring solar panels in series, I showed you how to confirm that they were correctly wired by checking the open circuit voltage of the 2-panel string with a multimeter. Technically, you could check that your panels are properly connected in parallel by measuring the strings short circuit current . BUT, many multimeters have a 10 amp current limit, and, in many cases, two solar panels wired in parallel have a combined short circuit current that is greater than 10 amps.
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Can I Connect Solar Panels Directly To A Battery
Although the answer is technically yes, you should never connect a solar panel directly to a battery. As solar power is generated at various intensities throughout the day, charge controllers modify the energy so that it can be efficiently stored in the battery. Using a charge controller between the solar panels and storage bank maximizes the systems production and protects the battery from overcharging, damages, and malfunctions.
Putting Solar Panels In Series
There are several advantages to putting solar panels in series, including a lower cost and simpler installation. Unlike parallel connections, series arrangements maximize power output for a longer period of time. In addition, series connections do not sacrifice power unlike parallel connections, series panels do not charge batteries when there is no sunlight. For more information, read the following sections. Continue reading to learn about the benefits of series connection. Heres a quick overview of the pros and cons of putting solar panels in series.
Solar panels connected in series have identical voltages and currents. The individual voltages of each panel will add up. Thus, the overall output of the solar array will be equal to the lowest-rated panel. An example of this is a solar array of eighteen-volt panels with a four-amp rating. In this case, the total power would drop from 324 watts to 216 watts.
A downside to installing solar panels in series is that theres a higher risk of shading. Because all the panels are interdependent, if one panel gets shaded, it will affect the entire array. However, this issue is not likely to occur if the panels are connected in parallel. Instead, installers prefer to avoid such places. In addition, shading will reduce the production of all panels. When placing solar panels in series, make sure that you place them in a protected area.
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Advantages And Disadvantages Of Series Connection
The first and maybe most important advantage is that the charging and discharging electrical current of the battery bank is lower. This is positive because it reduces ohmic losses in the form of heat and reduces costs because lower gauge sizes are needed for the cable that connects batteries and the charge controller. Also, this lower electrical current means that there will be fewer hot spots in terminals of connections, which drastically reduces the chances of fire or ignition. Another good thing about a series connection is that the same charging current will flow through all the batteries, meaning that they will all be charging/discharging at the same rate.
On the other hand, the main disadvantage of a series connection is that it has very low reliability because if one of the connections comes loose or breaks, then all the power is lost.
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How Many Solar Panels Can Be Connected To The Series
You can connect as many solar panels as you want, but one thing to remember is that the total nominal voltage of the solar array should not exceed then the total input nominal voltage limit of your charge controller.
You can use multiple solar charge controllers in one solar array if you want.
Important Disclaimer! all the information above is based on if you have the same size solar panels, if you dont keep reading.
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Solar Panel Parallel Wiring Diagram
Notes
- You may have to connect MC4 inline fuses between the positive solar panel cables and branch connector. Heres a good video showing you when you need to fuse your solar array.
- It is recommended that you use identical solar panels
- If the solar panels are not identical, they should have the same voltage rating
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Difference Between Parallel And Series Connection
The key difference between parallel and series connections.
- Parallel connection: The voltage of the solar panel will stay the same but the amps will add up
- Series connection: The amps of the solar panels will stay the same but the voltage will add up
Now lets discuss some advantages/disadvantages of having parallel and series connections. And what to do when you have different-sized solar
Case : Solar Panel Series Wiring For The 5kw Inverter
We bet some of you have already hypothesized how to satisfy these conditions. Lets confirm them, shall we?
We want 5kW of solar power. Given that each solar panel is 400W, we can start with 12 panels since that would mean a total of 4800W. Note that you can also create many series-parallel combinations since 12 is an even number with a decent amount of least common multiples.
We get it. For some of you, that previous paragraph involved a lot of nerdy stuff. Feel free to read it one more time to increase comprehension.
Now, we think more solar panels should be connected in series rather than parallel.
Why?
Imagine that you have a high voltage threshold of 550V. This would mean you could connect the entire 12 solar panels in a single series string. Doing our usual computation will yield the following results:
4800W < 5500W DC Maximum Input Power
100V < 480V < 550V V,rated
10A < 20A I,max
If you had connected the solar panels in parallel, you would have gone out of bounds if you linked more than two.
So, the easy answer to our 5kW solar rooftop plan is to connect 12 solar panels in series.
Thats it?
Thats it. However, what if you are constrained to a lower voltage limit for your inverter?
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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 dont join any of the solar panels together. Well 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 weve 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.
Solar Panel In Series Vs Parallel Whats The Difference
There are two ways to wire solar panels in a series or parallel to create an electrical circuit. Series wiring means the current flows through one panel and then to the next. The total voltage is the sum of the voltages of the individual panels. In parallel, each panel has its own voltage and current, and the wattage is additive.
The use of solar panels in series or parallel has a big impact on the amount of energy that can be collected from the sun. The most common form of solar panel is the single-cell solar panel, which uses one large silicon wafer to convert sunlight into electricity. In contrast, a solar panel array uses many smaller cells to generate more power. This is why arrays are more common and efficient than single-cell solar panels: they can collect more energy from the sun.
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Wiring Solar Panels When Using A String Inverter
String inverters have a rated voltage window that they need from the solar panels in order to operate. It also has a rated current that the inverter needs to function properly.
String inverters have maximum power point trackers in them that can vary the current and voltage to produce the maximum amount of power possible.
In most crystalline solar panels, the open circuit voltage is around 40 Volts. Most string inverters have an operational voltage window between 300 and 500 volts. This would mean that when designing a system, you could have between 8 and 12 panels in a series.
Any more than that would exceed the maximum voltage the inverter could handle.
The thing is, most solar panel systems are larger than 12 panels. So, in order to have more panels in the system, you could wire another series of panels, and connect those series in parallel. This allows you to have the right number of panels to meet your homes energy needs, without exceeding the limits of your inverter.
Schematics: Wiring Solar Panels And Batteries In Series And Parallel
Electrical equipment is rated by how much electricity they use, make, or store. For example, a 100W solar panel can make 18 volts and 5.5 amps . A 1200Wh battery is rated by both the 12V and 100Ah capacity. When wiring components together, the way they are wired will change the way the ratings are affected.
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Should You Wire Solar Panels In Series Or Parallel
This might sound vague and repetitive at this point. Still, you have to understand that the decision to wire your solar panels either in series or parallel highly depends on the conditions you need to satisfy.
Conditions to satisfy? What are those?
Recall that connecting solar panels in series increases the total system voltage sent to your inverter. On the other hand, parallel-connected solar panels increase the whole system current received by the same power inverter.
So when choosing a wiring configuration, your job is to make sure that the total system voltage, total power injected, and total system current fall within the inverters voltage, power, and current ratings, respectively.
The best way to drill this concept into you is through practice. So, in the next section, we will use all the things we discussed to decide which wiring configuration/s to use for a 1kW and a 5kW solar system.
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Connecting Solar Panels To House Wiring And Putting It All Together
Once youve looked at the specifications for your modules and inverter, its time to put the rest of the system together. After wiring your panels together in either a parallel, series, or series-parallel configuration, youll need to connect everything to your inverter.
From the inverter, connect it to the homes AC power box, and, if youre installing a grid-tied system, to the electrical grid. If the system youre installing includes solar storage, youll want to wire that to a charge controller to regulate the voltage coming from the panels and your inverter.
Finally, ensure youve wired your AC and DC disconnects, which are required by most building codes across the United States. DC disconnects are usually found inside the inverter or placed nearby, while AC disconnects are installed near the electric meter. These enable people to quickly cut the power coming from the panels into the home or from the house to the grid in the event of an emergency or for maintenance purposes.
When your system is wired and ready to go, youll want to make sure your array is grounded and bonded and ensure that there is no shock hazard associated with the system. Metal parts of the system need to be bonded to the ground, and conductive materials like metal boxes must be grounded together.
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Connecting Solar Panels Together In Parallel
The next method we will look at of connecting solar panels together is whats known as Parallel Wiring. Connecting solar panels together in parallel is used to boost the total system current and is the reverse of the series connection. For parallel connected solar panels you connect all the positive terminals together and all of the negative terminals together until you are left with a single positive and negative connection to attach to your regulator and batteries.
When you connect solar panels together in parallel, the total voltage output remains the same as it would for a single panel, but the output current becomes the sum of the output of each panel as shown.
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How Do You Connect Solar Panels To Batteries
Connect the positive wire from the solar panel to a battery cable with a fusible link between the battery and the solar panel. This will help prevent a fire or battery explosion in the event of a short in the wiring. Connect the negative wire of the solar panel to the negative terminal of the battery.
