Series, parallel, or mixed connection? Find out how to best connect your solar modules!

Do you want to install solar panels on your motorhome, campervan, or balcony and are looking for the most efficient way to connect them? Then you've come to the right place. The way you connect your solar panels – whether in series, parallel, or a mixed configuration – has a crucial impact on the performance, efficiency, and safety of your photovoltaic system.

Especially with balcony power plants and mobile solar systems on vans or motorhomes, the question often arises: What produces more electricity? What is safer? And how do I get the maximum output from my solar system? This decision seems technical and complicated at first glance, but with a little background knowledge it can be easily made – and can save a lot of money and hassle in the long run.

In this article, we'll take you on a clear and practical journey through the different types of solar panel circuits. You'll learn how series, parallel, and mixed circuits work, what their differences are, and which solution is best suited to your application – whether it's a balcony power plant or a mobile solar system.

You can find a comprehensive explanation of how solar modules work in our solar module topic area .

Our goal: To make your decision easier, so that you can optimally connect your solar modules and achieve the highest possible energy yield – efficiently, safely and tailored to your individual situation.

So, are you ready to get the most out of your solar energy? Then let's find out together how to properly connect your solar panels. Let's start with the basics: the difference between series and parallel connections.

Connect solar modules in parallel

In a parallel connection, all positive poles of the modules are connected together, as are all negative poles. This causes the current of the individual modules to add up , while the voltage remains the same . Generally, care should be taken to ensure that the full voltage is never reached, but rather that the voltage is always approximately 20% below the specified voltage, as solar modules can exhibit a higher voltage on colder days. This applies to both parallel and series connections of solar modules.

Let's take a look at the 100W solar module from Wattstunde with the following specifications:

Rated power (Pmpp)	100 Wp
Maximum daily yield in summer	400 Wh/d
Electricity (Impp)	2.40 A
Voltage at maximum power (Umpp)	41.76 V

The voltage remains the same as with a single module.	Total voltage = 41.76 V
The total current is the sum of the currents of all modules connected in parallel.	Total current = 2.40A * 3 = 7.20A
The total power output is the sum of the power output of all modules.	Total power output = 100 Wp * 3 = 300 Wp

Result of the parallel connection: A parallel connection of three 100 Wp modules results in a total voltage of 41.76 V at a current of 7.20 A and a total power of 300 Wp.

Advantages of parallel connection:

• Reduced impact from shading: In a parallel circuit, a partially shaded module does not affect the performance of the other modules. Each module can operate independently.
• Same voltage across all modules: In a parallel circuit, the voltage remains the same across all modules, which simplifies the requirements for the charge controller or microinverter .
• Flexibility in expansion: It is easier to add additional modules to an existing parallel circuit, as the voltage remains the same and only the total current increases. Caution: The maximum connected load of the charge controller/microinverter must not be exceeded.

You can find everything you need for the right cabling, protection and connection in Accessories & Installation .

Disadvantages of parallel circuits:

• Increased total current: Because the currents are added together, this can result in a high total current, requiring thicker cables and stronger connectors.
• Potential imbalances: Connecting modules with different power ratings in parallel can lead to imbalances and inefficient use. Ideally, modules should have identical electrical characteristics.
• Potential problems with the system voltage: Since the voltage is equal to the voltage of a single module, careful attention must be paid to ensuring that the system voltage meets the requirements of the charge controller or microinverter .

The decision to use a parallel connection depends on the specific conditions and requirements of the solar power system. For systems that are susceptible to partial shading or require flexibility for expansion, a parallel connection can be a suitable choice despite its disadvantages.

Connect solar modules in series

In a series connection, the positive and negative terminals of successive solar modules are connected: the positive terminal of one module is connected to the negative terminal of the next. This type of connection causes the voltage of the individual modules to add up , while the current (measured in amperes) remains the same .

Let's take a look at the 100W solar module from Wattstunde with the following specifications:

Rated power (Pmpp)	100 Wp
Maximum daily yield in summer	400 Wh/d
Electricity (Impp)	2.40 A
Voltage at maximum power (Umpp)	41.76 V

Total voltage = RPM per module * number of modules	Total voltage = 41.76V * 3 = 125.28V
The current remains the same as with a single module.	Total current = 2.40 A
The total power output is the sum of the power output of all modules.	Total power output = 100 Wp * 3 = 300 Wp

Result of the series connection: A series connection of three 100 Wp modules results in a total voltage of 125.28 V at a current of 2.40 A and a total power of 300 Wp.

Advantages of series connection:

• Increased voltage: The total voltage corresponds to the sum of the voltages of all modules connected in series.
• Reduced cable losses: Higher voltages lead to lower currents, which reduces losses due to resistance in the cables.
• Simpler cabling: Fewer connecting cables and components are required for connecting modules in series.

Disadvantages of series circuits:

• Susceptibility to shadows: If a module is partially shaded, this can affect the performance of the entire series.
• Potential problems with high voltages: The increased overall voltage can lead to safety concerns and requires careful installation.
• Troubleshooting difficulties: A defective module or connection problem affects the entire series.

The choice between series and parallel connection depends on many factors, including the specific requirements of the solar system, potential shadows, and the overall configuration of the system.

Hybrid or mixed circuit - combine series and parallel circuits

A hybrid system combines series and parallel connections of solar modules to optimize both voltage and current. First, several modules are connected in series to increase the voltage. These series connections are then connected in parallel to increase the current. The result is a system that utilizes the higher voltage from the series connection and the higher current from the parallel connection.

Example of a mixed circuit using the 100 W solar module from Wattstunde:

Let's look at this using the 100-watt solar panels as an example. Here are the key details:

Rated power (Pmpp)	100 Wp
Maximum daily yield in summer	400 Wh/d
Electricity (Impp)	2.40 A
Voltage at maximum power (Umpp)	41.76 V

Here's how to connect them in a mixed circuit:

Step 1: Connect two modules in series

Total voltage: Add the voltages together.	Total voltage = 41.76V * 2 = 83.52V
Total current: remains the same as with one module.	Total current = 2.40 A

Step 2: Connect two series in parallel

Now you take two such series and connect them in parallel.

Total voltage: remains the same as the voltage of a series.	Total voltage = 83.52 V
Total current: Add the currents together.	Total current = 2.40A + 2.40A = 4.80A

Total output of the plant:

Total power output: Sum the power output of all four modules.

Total power output = 100 Wp * 4 = 400 Wp

Result of the mixed circuit: Total voltage 83.52 V, total current 4.80 A, total power 400 Wp.

Advantages of the mixed circuit:

• Optimal energy utilization: Combining the advantages of both circuit types.
• Increased system flexibility: Voltage and current can be adjusted to system requirements.
• Reduction of performance losses: Partial shading has a less severe impact on the overall system.
• Scalability and expandability: Systems can be expanded more easily.
• Efficient use of inverters: Optimization of voltage and current for more efficient operation.

Disadvantages of the mixed circuit:

• Complex installation: Planning and installation are more demanding.
• Higher costs: Additional hardware and installation effort may be required.
• Maintenance and troubleshooting: Diagnosis can be more difficult.
• Risk of imbalances: Inconsistencies can affect efficiency and lifespan.

When should you connect your solar panels in parallel, when in series, and when does a mixed connection make sense?

Now that we know how solar panels are connected in series, parallel, or mixed configurations, let's look at where each type makes sense. The choice between these connection types can significantly impact the performance and efficiency of your solar system, whether it's for a camper van or a balcony power plant. In the following sections, we'll give you concrete examples to help you make the optimal decision for your project.

Motorhome: Solar panels on the roof

Series connection:

• Ideal for: Motorhomes that require a higher voltage and where the risk of shading is relatively low.
• Example: A motorhome that mainly travels in sunny regions and whose roof area is large enough to avoid shading.

Parallel circuit:

• Ideal for: Motorhomes that frequently park in wooded or mountainous areas where partial shading is common.
• Example: A camper that is often parked in the shade or where individual modules are partially shaded.

Mixed circuit:

• Ideal for: Motorhomes in changeable environments with varying sunlight and potential partial shading.
• Example: A camper who travels in both sunny and wooded areas.

Balcony power plants

Series connection:

• Ideal for: Balcony power plants without direct shading, provided all modules are evenly illuminated.
• Example: A balcony power plant on an upper floor without a roof or taller buildings in the immediate vicinity.

Parallel circuit:

• Ideal for: Balconies with potential partial shading from railings, plants or surrounding buildings.
• Example: A small balcony power plant where parts of the balcony are shaded at certain times of day.

Mixed circuit:

• Ideal for: Densely built-up areas with frequently changing or uneven sunlight.
• Example: A balcony that is partially shaded by neighboring buildings can be optimized by using a mixing circuit.

In all cases, the choice of the ideal wiring configuration depends on the specific conditions and objectives. While series wiring is advantageous under optimal lighting conditions and when higher voltage is required, parallel wiring offers benefits under variable lighting conditions and when shading effects need to be minimized. A mixed wiring configuration combines both approaches and is particularly effective when both a stable voltage and high current are needed under changing conditions.

We hope this article has helped you better understand the differences and respective advantages. If you now want to select components or size your setup: Click here for the solar calculator .

At SOLARKONTOR, we specialize in advising on and creating specific offers for balcony power plants and solar solutions for motorhomes. Our team is ready to answer your questions and support you in planning and implementing your individual solar system. Whether you need help choosing the right circuit type or are looking for a customized offer for your project – don't hesitate to contact us.