So How Do You Decide Between Series And Parallel
The first step is to confirm the solar capacity you want to install. Second step is to understand how many solar panels you need. Third step is to find a suitable inverter and understand the specifications on the inverter. Fourth and final step is to design the string configuration based on solar panel and inverter specifications.
Why Is Different Wiring Required
The output voltage and current are the key differences between wiring solar panels in series and parallel. When many panels are connected in series, the output voltages add up, and the output current stays the same. When multiple solar panels are connected in parallel, their output currents add up, but their output voltages remain constant.
If you want to connect your solar panels in parallel, youll need high-amperage cabling and components. When you choose serial wiring for your solar system, the voltage and amperage will be higher, putting less strain on your cables and components. It has an impact on your systems performance as well as the inverter youll be able to use. You want your panels to be wired so that they provide you with the most savings and a higher return on investment.
How Should I Wire My Solar Panels
Before we start wiring anything, we need to understand electrical lingo and state regulations governing the solar industry. Its so important to string our solar panels correctly.
These terms are not interchangeable, but each plays an essential role in solar panel wiring. Think of it this way they are dependent on each other. You cant have one without the other.
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Common Arguments For Parallel Over Series
Recently weve been getting a ton of comments arguing for wiring solar panels in parallel and they always go something like this:I want max solar output from my solar panels and if I wire in series, park under a tree, and get shading on part of my array, It significantly decreases power to the entire array.andI want max solar output from my solar panels and if I wire in series and a panel breaks It significantly decreases power to the entire array.
In our 3+ years of being on the road, neither of these have been a problem.Fortunately, Ive developed a highly-sophisticated strategy for solving both of these problems and still wiring in series and lucky for you, Ive made diagrams for both of them.The first diagram fixes the problem in regards to getting max solar output when your camper is parked near a tree thats causing partial shading to your solar array.
This next diagram fixes the problem in regards to getting the max solar output of an array with a broken panel.
There have been tests done showing how one bad panel or shading on one panel will decrease the output of the entire array. All of that is true Im not debating that.My point is this: If you are TRULY worried about getting the maximum output from your solar panel array park in the sun and maintain your solar panels.
Solar Panels In Series Of Different Voltages
In this method all the solar panels are of different types and power rating but have a common current rating. When they are connected together in series, the array produces 21 volts at 3.0 amps, or 63 watts. Again the output amperage will remain the same as before at 3.0 amps but the voltage output jumps to 21 volts .
Finally, lets look at connecting solar panels in series with completely different nominal voltages and different current ratings.
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Solar Panels In Series Of Same Characteristics
In this method ALL the solar panels are of the same type and power rating. The total voltage output becomes the sum of the voltage output of each panel. Using the same three 6 volt, 3.0 amp panels from above, we can see that when these pv panels are connected together in series, the array will produce an ouput voltage of 18 Volts at 3.0 Amperes, giving 54 Watts at full sun.
Now lets look at connecting solar panels in series with different nominal voltages but with identical current ratings.
Solar Panels Series Or Parallel: The Evergreen Solar Dilemma
Solar panels series offer good expansion potential and lower cost, parallel connections are less prone to shading issues, while hybrid options combine the best of both worlds.
Series connected arrays produce higher voltages and low amperage, allowing for growth and low installation costs. In contrast, parallel wiring models produce low voltages and high amperage and are less prone to issues such as array shading. Hybrid, or series/parallel, wired panels combine the characteristics of both types allowing for excellent installation flexibility.
Another important consideration is how your choice of connection model impacts the rest of your installation equipment choices. For example, series circuits favor MPPT charge controllers, while parallel models generally work best with PWM types. The same holds for your choice of cabling, connectors, and termination hardware.
Our blog post examines these theories in detail and also gives insight into which model you should choose.
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Series V Parallel In Shade
The suns height in the sky affects the energy produced, varying throughout the day and the year.
Cloud and shade fall on the solar panels. It may not be much of an issue for solar farms in wide-open fields, but it is on an RV or campervan.
Parking under a tree or in a buildings shadow varies power output from the panels, depending on how theyre wired.
When shade hits any part of a solar array wired in parallel, the power output from that panel reduces significantly. BUT, any other panels in the configuration are unaffected.
Conversely, when shade hits any part of a solar array wired in series, the power output from that panel reduces a lot. AND every other panel in the configuration is dragged down with it.
Wiring Solar Panels In Parallel
In a parallel system, each solar panels positive terminal is connected to the next panels positive terminal, and negative terminals are also connected to one another. When an installer wires your solar panels in parallel, each panels wires are connected to a centralized wire leading from the roof. The amps of electrical current for each solar panel are summed together, but the system voltage stays the same.
Wiring your solar panels in parallel results in more wires running from your solar panel system, but often can increase overall energy production because the system isnt limited by any individual panel.
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What Are Volts Amps Ohms And Watts
We talk about electricity in terms of volts, amps, ohms, and watts. Heres a quick recap of what each of these terms means. To make things easy to understand, we will use a water analogy. Since electricity flows in the same way as water, imagine an electrical circuit as a series of connected water pipes. Trust me its simple.
Volts
Voltage is a measure of electrical potential energy. In our water pipe analogy, voltage represents the waters pressure.
Amps
Total power = 80 Volts x 5 Amps = 400 Watts
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.
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What Does It Mean When A Solar Panel Is In Parallel Wiring
When solar panels are wired in parallel, the positive terminals of one panel are connected to the positive terminals of another panel, and the negative terminals of both panels are connected.
Positive wires are connected to a positive connector in a combiner box, whereas negative wires are connected to a negative connector. A PV output circuit is created when many panels are connected in parallel.
The amperage increases when solar panels are wired in parallel while the voltage remains constant. If you wired the same panels in parallel as in series wiring, the systems voltage would stay at 40 volts, but the amperage would rise to 10 amps.
Parallel wiring allows you to have additional solar panels that produce energy without exceeding your inverters working voltage constraints. Inverters are also limited by amperage, which you can overcome by connecting your solar panels in parallel.
How Many Solar Panels Do I Need For 3 Kw
How many solar panels do I need to produce 3kw of energy? This is a question that many people have, and the answer can vary depending on a number of factors. However, we will try to give you a general idea of how many solar panels you need for 3kw of energy production.
First, it is important to understand that not all solar panels are created equally and there are many different panels. Some solar panels are more efficient than others, so you may need fewer solar panels to produce the same amount of energy. Another factor that determines how many solar panels you need is the size of your home or business.
If your home or building is large, you will need more solar panels than if it is small. For a 3kw home, you will need between 1.5 and 2kW of solar panels. This means that if your home is 300 square feet, you will need between 75 and 100 solar panels. Finally, the location where you plan to install your solar panels also matters.
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Advantages Of Series Connection
- You need less cable.
- Your cable doesn’t need to be as thick as that for panels connected in parallel because you’re carrying higher voltage and lower current.
- As the temperature of the PV modules in a solar panel heats above 25°C, there is a drop in the voltage that the panel can produce. The higher that temperature is, the lower the voltage you can obtain from the panel. If you have one single solar panel, it’s entirely possible for the voltage output of the panel to be too low to charge your battery. However, if you connect multiple solar panels in series, you’re combining the voltage of all of your solar panels. So if you have two or more panels, you’re more likely to keep your voltage at a level that will charge your battery in hotter weather.
Pros Of Solar Panels In Series
Most of the benefits for a series solar panel system are found when the system is being used for smaller jobs. If you are camping off-grid and want small appliances to work, or you are traveling in a camper with solar panels on the roof, this would be a good option for you.
Here are the pros of series solar panels:
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Less Wiring is Used: The more wire that is required, the more expensive a project is and the more difficult the installation. Plus, if you are off grid and want to travel, having more wires might get in your way. More wires are also heavier, bulkier, and harder to work with. Thus, many solar enthusiasts like the simplicity of the series wiring system.
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Easier For Long Wire Runs: The knowledge that there are fewer wires to deal with also works into this pro as series-wired solar panels are preferred if you need to run a long wire. The reason is that there are fewer wires and only a few local connections that run, one right after the other. Therefore, if there is a bit of a distance between the panels and the controller, series wiring is easier to manage.
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Setting Up Multiple Batteries In Parallel Vs Series
For most applications, a single battery with 100 AH will not supply enough energy. To get more power, we could buy multiple batteries. That leads to the question: How do I set up my multiple batteries? There are two ways, in Series or in Parallel. When batteries are wired in Series, the voltage is added. When batteries are wired in Parallel, the amp/hours are added. If we wire four 100 amp/hour batteries together in Parallel, our system will have 400 total amp/hours of energy at 12 volts. Most common battery setup will want to wire their batteries in Parallel, but it is possible to wire in parallel and series to achieve 24/48 volts. For most applications however, 12 volts is already a useful voltage.
To wire a battery in parallel, we use wires to connect each of the positive terminals of our batteries, then, using another wire, connect all the negative terminals of our batteries. This will increase our amp/hour storage while maintaining the same voltage.
To wire a battery in series, we wire the positive of one battery onto the negative of the next one, repeating this process for each battery in our setup. This adds up the voltage of our setup while the amp/hour storage remains the same.
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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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.
Mixing Solar Panels & How Best To Wire Them
In an ideal world, your camper solar setup will consist of a set of identical solar panels.
Theyll all be the same brand, type, and wattage, so operating currents and voltages will all be the same.
But we dont live in an ideal world.
Perhaps you have a few mismatched solar panels to kick off a budget solar setup.
What if youre on the road, living in your van full-time, and need to replace an existing solar panel or want to add another to your setup but cant source the same panels?
Can you add a different panel?
Yes, you can but determining how best to configure the system isnt as straightforward.
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Solar Panels In Series
In a series connection, the NEGATIVE output cable of the first panel is connected to the POSITIVE output cable of the second panel. Then the NEGATIVE output cable of the second panel is connected to the POSITIVE cable of the third panel. And so on, for however many solar panels you have.
Finally, the POSITIVE cable of the first panel and the NEGATIVE cable of the last panel are connected to the solar charge controller.
* Solar fuses are technically required in this wiring example, but are excluded here for simplicity.
In a parallel connection, the POSITIVE output cables from all the solar panels get joined together using a branch connector. The same is done for all the NEGATIVE output cables.
The branch connectors take all the positive and negative cables and output a single POSITIVE and NEGATIVE line, which then gets connected to the solar charge controller.
For simplicity sake, the above diagram does not include solar fuses. We talk more about that below.
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Sample Calculation For Series
In a series-parallel connection, you put in parallel two or more strings of panels, each of which is in series.
To keep it simple, well use whole numbers.
Following the pattern of the previous two sample calculations in this article, well use panels rated at 100W each with a Voc equal to 20V and output current of 5A.
As an example of paralleling two series strings with four modules each:
For each series string:
P = x 5A = 400W
Next, we put the two series strings in parallel with each other to get the total estimated power output of this series-parallel PV system:
P = x 80V = 800W
Note: Putting all eight panels in series is possible only if your charge controller is rated for approximately 200V, which is not typical. Similarly, designing an array with these eight panels in parallel would create an amperage thats quite high . Youd need a charge controller that could comfortably handle slightly more than that.
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