Solar Panels: Series Or Parallel Which Is Better
Now that we understand the difference between wiring solar panels in series vs. parallel, we can talk about which option is better. So, should you wire your solar panels in series or parallel? Well, again, it truly depends on your application.
Connecting your solar panels in series is often preferred if youre able to spend most of your time in unshaded locations. The main reason for this is that your solar panel system will be more efficient and will perform better at the beginning and end of the day and when its cloudy. Heres why.
Batteries require a higher voltage than their nominal voltage to charge. For example, our lithium batteries need 14.4 volts to start charging. Most solar panels in the 100-watt range have an output voltage between 18-20 volts. To reach the 14.4 volts required to charge your batteries, solar panels in parallel would need to be operating at 75% capacity or more.
Solar Panels In Series Of Different Currents
In this method all the solar panels are of different types and power rating. The individual panel voltages will add together as before, but this time the amperage will be limited to the value of the lowest panel in the series string, in this case 1 Ampere. Then the array will produce 19 Volts at 1.0 Ampere only, or only 19 watts out of a possible 69 watts available reducing the arrays efficiency.
We can see that the solar panel rated at 9 volts, 5 amps, will only use one fifth or 20% of its maximum current potential reducing its efficiency and wasting money on the purchase of this solar panel. Connecting solar panels in series with different current ratings should only be used provisionally, as the solar panel with the lowest rated current determines the current output of the whole array.
How To Connect Batteries In Series
Connecting batteries in series increases the amount of voltage. It will not increase the ampere capacity. For example, if you connect two 12V 100Ah batteries in series, the combined voltage will be 24V. The 100 ampere hour capacity remains the same.
Before connecting batteries in series, make sure they have the same voltage and rated capacity. Mixing and matching suits your closet, but it won’t work when creating battery settings! Doing so may be dangerous and may damage your battery.
Here is how to connect the batteries in series, step by step:
Note: You can also charge multiple batteries in series. But please make sure that the charger you use matches the total voltage of all batteries.
In addition, it is important to know that most but not all lithium ion batteries can be connected in series. For more information, refer to the user manual of the battery.
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Series Batteries: Advantages And Disadvantages
For large applications that require high voltage , series-connected batteries are usually a better choice. Higher voltage means lower system current, allowing you to use thinner wiring. The voltage drop will also be smaller.
The main disadvantage of series and parallel batteries is that all your applications must operate at higher voltages. For example, if you connect two 12V batteries in series, you will end up with 24V. Unless you use a converter, you will not be able to power any 12V devices.
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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Should Solar Batteries Be In Series Or Parallel
In off-grid wind and solar power systems, the greater the direct voltage for charging the batteries, the lesser energy is lost along the cables. So for example, a 24V system is better than a 12V system. Combining the parallel connection with series connection we will double the nominal voltage and the capacity.
Connecting Solar Panels In Series
The series connection is done by wiring the positive terminal of each panel to the negative terminal of the next panel until the final panel is connected to the charge controller or inverter.
In the series connection the voltages of all solar panels are summed up and the current is maintained the same for all the panels. The set of solar panels connected in series is known as a string.
As stated before: lower voltages imply higher currents and higher voltages imply lower currents.
This statement is very important for series connection, because as this configuration increases voltage values with every added panel, then, the overall current provided by the system will be lower.
This translates in savings due to lower wire sizes and cable length, and also in higher efficiency of the PV system .
However, the main disadvantage of this configuration is low reliability of the system when connected in series. In other words, as the whole system is connected by one single cable, if the cable fails then all the system will be affected.
When one of the solar panels in the string is shaded, whether by a tree or a cloud, the overall performance and efficiency of the system is affected.
Shading can even become a bigger problem in this configuration because a shaded part creates resistance in the current flow. This effect creates so called hotspots. Hotspots are sections with increased temperature, and depending on the wiring and the system size can even represent a security problem.
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Should I Install My Solar Panels In Series Vs Parallel
How you choose to wire your solar panels depends on your installation design , whether youre connected to the grid or not, and the size of your installation.
Keep in mind that there are positives and negatives to each system. While it may be easier to wire your solar panels in series, a disruption to one of the elements will disrupt the entire circuit, so it is less reliable. On the other hand, panels connected in parallel need larger, more expensive wire .
Ideally, your solar energy plan should include some type of optimization tracking such as MPPT in addition to any modifications made to the solar cell itself, as it may be more beneficial to perform energy tracking rather than modify the wiring of your solar panels. And dont forget about avoiding this whole issue entirely and going with microinverters!
Image Credits under CC License via Flickr 1, 2, 3
Wiring Photovoltaic Panels In Series
To do this wiring, make two sets of PV panels and connect them in series. This way, you will have two pairs of solar panels connected in series. Now, connect the two sets of series connected solar panels in parallel as shown in the following fig. Now, you are having four 12V, 10A solar panels connected in series-parallel configuration.
As a next step, you can connect these solar panels to a charge controller. A basic DC load can be directly powered up by connecting it to the charge controller.
The AC load can be powered up in two ways. Firstly, it can be directly powered up by solar power during the normal sunshine . Secondly, the AC load can be powered up by the stored power in the batteries using an inverter during shading . Keep in mind that the number of solar panels and batteries depends on the load requirements where solar panels keep charging the batteries as well as power up the AC load.
The following solar panel and battery wiring diagram shows how to wire a four 12V Solar Panels in series-parallel connection to a 24V, 400Ah battery with an automatic inverter system. Note that the number of solar panels and batteries depends on the systems design and load requirements i.e. multiple batteries and solar panels can be connected in series, parallel or series parallel connection to increase the Ah rating and storage capacity. .
- Current is additive while voltage is the same in parallel connection.
- Current is the same while voltage is additive in series connection.
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What Its Best For
Solar panels in series are optimal in unshaded conditions. If shade covers a single panel of your series array, it will bring down the whole systems power output. Each panel in a series connection is critical.
Solar panels in series are also best if you need a low-amperage system. To calculate the output power of a solar system, multiply the voltage by the current. If you have a higher voltage system, your amperage will be lower. Lower amperage allows you to use smaller gauge wires which are less expensive and easier to work with.
One important thing to know is that you will need to use an MPPT charge controller when wiring your panels in series. MPPT charge controllers regulate the voltage and current from the solar panels to match the battery banks voltage without sacrificing power. If you use a PWM controller, the battery will pull the total panel array voltage down to match it, and you will lose a lot of power.
Mc4 Connectors For Wiring Solar Panels In Series Vs Parallel
MC4 Connectors are the way most solar panels are wired together. Sure, some people just cut off the connectors and splice the wires together and thats fine, but for those of us who like the ease of use of the MC4 connectors, there are a few differences between parallel and series.Solar panels typically have MC4 connectors built onto the ends of their built in wires like this:
And in the following picture, this is how you would be wiring the panels up in series and in parallel using MC4 connectors:
In 90% of installations, when wiring in series, the solar panels can be placed close enough together so that the positive lead of one panel will reach the negative lead of the adjacent panel. This means you wont need extra MC4 connectors to make the inter-panel connections.If that solar panel arrangement works for your setup, youll only need 1 pair of MC4 connectors for the whole series.For Parallel wiring, youll need a pair of MC4 connectors per solar panel you use.
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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.
What Is A Circuit
Before we get into whether solar panels are better connected in series or in parallel, lets talk a little about wiring basics, starting with circuits. An electronic circuit is simply a path electrons can flow through. The simplest circuit is a battery, wires, and light bulb.
As electrons move through a circuit, they create voltage the difference in charge between two points and current the rate at which charge is flowing . Check out this great 5 minute video to understand the difference between voltage and current its going to come in handy later on!
Each electrical component in a circuit affects current flow by changing its electrical properties. For example, resistors dissipate energy, while capacitors store electrical charge. Conductive wires enable current to flow. The configuration, or placement, of these components within the electrical circuit affects the flow of current and its electrical power.
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How Many Batteries Do I Need
We never want lead deep cycle batteries to go below 50% charge to avoid damage. This means that well need a battery setup that has an energy capacity of at least twice our drain. In our example above, wed want at least 4500 watt hours. This means wed want at least two lead acid batteries with 200 amp/hour ratings.
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.
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Mixed Wiring Of Solar Panels
A combination of series and parallel connection is also possible.
Picture of the combination of series and parallel connection of solar photovoltaic panels
Indeed, this depends on the maximum possible total output voltage and maximum possible total output current of the solar array, which are limited by the maximum input voltage and the maximum input current of your charge controller or inverter .
Calculations show you how many panels and how to wire.
What you have to remember is that the series connection increases voltage, while the parallel connection increases current.
Both series and parallel connection result in more installed wattage, which goes down should you decide to wire solar panels of different ratings.
If you decide to apply a mixed connection, its practical your solar array to comprise an even number of panels , for example, 4 panels or 6 panels .
If the system sizing calculations result in an odd number of panels , and you are sure you are not going to add more panels in the future, its practical to use either series or parallel wiring.
If anyway you prefer wiring solar panels of different ratings rather than spending money to buy similar solar panels and end up with an installed wattage youll never need, it is a smart idea to separate the panels in two sets and wire them in parallel.
In such a case, however, you should either search for a charge controller with at least two input feeds or install a second charge controller .
Should I Connect My Solar Panels In Series Or Parallel
CAN I MIX DIFFERENT SIZE SOLAR PANELS?
A common question asked by many iTechworld customers:
“Can I join one of your 120W Solar Panels with my existing 200W Solar Panel on my roof to get 320W?”
Mixing and matching Solar Panels can be done. In order to get the results you are looking for though you must take all the factors into consideration beforehand. In this blog I will look at the different ways of connecting Solar Panels together to make an array. I will break down the basic fundamentals to give you an idea of what wattage you should expect from your array.
When you are looking to connect Solar Panels produced by different manufacturers together the problem does not come from different manufacturing styles or cell type, it comes from the electrical characteristics of the solar panels. Watts, Volts and AMPS.
There are two ways to wire up Solar Panels. Series and Parallel. Both have their own purpose and applications and both have different outcomes when hooking up Solar Panels of different wattage together.
Firstly lets take a look at connecting Solar Panels in series. Solar Panels are usually connected in series to obtain higher output voltage. This is usually the case with 24v systems.
If we connect 4 x 150w Solar Panels in series the total power is calculated as follows:
Total power = 150W + 150W + 150W + 150W = 600W
However if we were trying to create 620watts of power using different wattage solar panels we would have a different outcome.
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Which Wiring Works Better Series Or Parallel
In theory, parallel wiring is a better option for many electrical applications because it allows for continuous operation of the panels, even if one of the panels is malfunctioning. But, it is not always the best choice for all applications. You also might need to meet certain voltage requirements in order for your inverter to operate.
A critical balance of voltage and amperage needs to be achieved in order for your solar array to perform at its best. So, in most cases, a solar installer will design your solar array with a hybrid of both series and parallel connections.
Advantages And Disadvantages Of Parallel Connection
Alternatively, a parallel connection offers the best reliability since even when one of the strings of batteries suffers some malfunction, the rest of the batteries will continue working and will not interrupt the power supply. Of course, the power output of the battery bank will be lower, but it will not leave the load completely out of service. Moreover, by making a parallel connection, you will increase the capacity of your system.
However, a parallel connection also means that the charging current that is used to charge all the bank will be divided between every string of batteries. Although theoretically, it should be equal, the truth is that due to manufacturing differences or low-quality connections, the charging and discharging current that will flow throughout the strings can be different. This creates a unbalance that is undesirable for the long-term performance of the battery bank.
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