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If you’re sick and tired of load-shedding disrupting your life, you may want to consider installing a solar panel system at your home to generate electricity.
With sunlight in abundant supply in South Africa, photovoltaic panels and a balance of system + solar battery storage can provide the energy security that Eskom can’t.
An essential step in producing off-grid electricity for your home is connecting solar panels.
No matter which PV panels you purchase, there are two basic ways to wire them together to create a solar array.
Series or parallel.
Each has its benefits. The right way for you depends on numerous factors.
Want to learn more?
Read on to find out.
The Basics of Connecting Solar Panels
If you’re using more than one solar panel, connecting each PV module together then to a portable power station or other balance of system is essential.
Solar panels on their own are useless.
The magic happens when you connect a PV module to a solar inverter or charge controller to convert or store electricity.
Regardless of the manufacturer, the fundamentals of residential solar power systems stay the same…
Solar panels made up of multiple photovoltaic cells capture photons from sunlight and convert them into direct current electricity using the photovoltaic effect.
Direct current (DC) is sent via cables or wiring to an inverter, where it’s converted to Alternating Current (AC or “household”) electricity or stored in a solar battery as DC and converted to AC when discharged.
In a solar panel array, HOW you wire the PV modules together determines essential qualities of the electricity produced.
Connecting Solar Panels in Series vs. Parallel. What Is the Difference?
In most currently available solar panel arrays, connecting multiple solar panels to each other is simple.
Most solar panels use a Universal Solar Connector, and many manufacturers provide the necessary cables to wire numerous modules together.
However, it’s essential to understand that there are two options for connecting multiple PV panels.
Should you connect your solar panels together in series or parallel?
Or a hybrid of both?
The right answer depends on the number of PV modules, the planned layout, and your electricity generation goals.
So, what’s the difference?
- Series wiring increases the sum output voltage of a solar panel array but keeps the amperage the same
- Parallel wiring increases the sum output amperage of a solar panel array while keeping the voltage the same.
The choice you make can have a significant impact on your system’s overall performance.
This article will examine the pros and cons of series and parallel connections between solar panels of the same rated power and model.
Mixing and matching PV modules with different specs or manufacturers is possible but much more complex than connecting multiple PV modules of the same model.
If you’re starting from scratch, you can make your life easier by installing multiple panels of the same make and model.
Before we dive deeper, it’s crucial to note that wiring in series or parallel impacts your PV array’s combined DC output in volts and amps. Series or parallel connections do not directly impact total output wattage.
(Source: Alternative Energy Tutorials)
Series Wiring
To wire solar panels of the same model and rated power in series, wire the positive terminal to the negative terminal of each panel.
Once the array is connected, you’ll have a single positive/negative output to plug into your portable power station or other balance of system.
In series-wired solar panel arrays, the overall output voltage accumulates.
As shown in the above diagram, each panel’s output is 6 volts. At the end of the series, the cumulative output is 18V (3 panels x 6V = 18V).
It’s essential to understand that in series configurations, the total output voltage increases with each panel added to the series, but the amperage remains constant.
Series connections are frequently deployed in grid-tied systems that require a voltage of 24V or higher.
(Source: Alternative Energy Tutorials)
Parallel Wiring
Connecting solar panels in parallel requires wiring each panel’s positive terminals together and then all the negative terminals to each other.
Essentially, the opposite of series wiring, with parallel, amperage accumulates and voltage stays constant.
Using identical panels to the series wiring diagram, the amperage per panel is 3V.
The total DC output will be 9 amps (9A) and 6 volts (6V).
This is the formula:
3A x 3 PV panels = 9A total output
The voltage stays the — the DC output remains 6V no matter how many solar panels you connect.
If you have a 10-panel array connected in parallel with 6V/3A of rated power output, your maximum DC output potential is 6V/30A.
Pros and Cons
Pros of Series Connections
Voltage Adds Up
If you need a high voltage installation — as is common with on-grid systems — series or hybrid series/parallel wiring is likely required.
Even for off-grid applications, a series connection is the way to go if your use case is better met with a higher voltage than amperage.
Slightly Higher Output and Efficiency
All things being equal, series connections will output slightly more electricity from the solar array than other wiring methods. Less power is lost transmitting electricity over distances to your solar inverter or charge controller through a series connection.
Less Expensive Cables
Though the savings are unlikely to be substantial, parallel connections require thicker gauge wiring. Series connections may cost slightly less to wire the same number of panels.
Best for Long Distance
Depending on how far the cables run from the beginning of your array to your balance of system, series connections may be more efficient. Voltage travels better than amperage over extended distances.
Cons of Series Connections
Susceptible to Shade
With a series connection, the cumulative output of the entire array is determined by the production of each individual solar panel.
If you have 10 PV modules with a rated voltage of 6V each, the maximum potential output during peak sun hours is 60V. However, if one panel is obstructed by shade and only produces 4V, the array’s output will be reduced to 4V per panel. Instead of 60V of production, your array will output 40V.
If a section of your installation area is obstructed during peak sunlight hours, consider parallel or hybrid wiring instead.
High Voltage is Hazardous
Increasing the voltage output of your solar panel array has benefits. However, high voltage is dangerous, and working with it increases installation risks. It’s best to work with a professional installer for large series wired solar arrays.
Pros of Parallel Connections
Current Accumulates
Each PV module you add to your solar array in parallel adds its direct current production to the overall DC output.
Less Prone to Decreased Output from Shade
Unlike series connections, the overall output of parallel wired arrays does not rely solely on the performance of each individual module. If one solar panel is obscured from sunlight for part of the day, the arrays’ overall output is not affected by any more than the reduction in current in the affected module.
Shaded panels contribute less production to the total output, but the maximum output of the panels receiving direct sunlight remains the same.
If you have 10 panels that output 3A of current in direct sunlight, but two are covered in shade, reducing their output to 2A, the cumulative output of your array will be reduced by 2A. The combined output is 28A instead of 30A because each shaded panel produces one fewer amp.
With rooftop installations, parallel wiring is often the obvious choice.
It’s not unusual for a significant portion of your installation surface area to be hit with shade from trees or other buildings for part of the day.
If the panel’s positioning means it never or seldom gets direct sunlight, you won’t be getting your money’s worth, and you should move it.
PV modules produce electricity on overcast days but rarely their full-rated power.
Solar panel performance depends entirely on how much solar irradiance (sunlight) the array receives during the day.
Solar panels don’t “work” at night.
Low Voltage
Connecting additional PV panels in parallel increases current without increasing voltage.
As a result, parallel wiring can be ideal for 12V power systems, like those found in caravans and RVs.
Also, consider your solar inverter or charge controller’s maximum voltage input.
If you exceed the voltage capacity of your balance of system, it will shut down automatically or cause permanent damage to components.
Cons of Parallel Connections
Decreased Efficiency
The more solar panels in your array, the more electricity is lost to inefficiency. Parallel wiring is less efficient at transmitting power over distance.
Lower Resistance to Heat
Because solar panels rely on sunlight to produce electricity, many people don’t realise that PV panel performance suffers in extreme heat.
Peak sun exposure optimises electricity production, but the efficiency of photovoltaic material per square meter declines rapidly as the temperature rises above 35°C.
The photovoltaic effect harvests photons from sunlight, not from heat.
More Expensive Wiring
Direct current flows through circuits like water passes through a hose.
The more output you require, the wider the cable has to be.
High gauge wires are also less efficient at transmitting electricity over long distances.
For this reason and others, parallel connections are typically used only in small off-grid installations.
(Source: Electrical Technology)
Hybrid Setups (Series-Parallel)
For large residential solar panel arrays, a hybrid configuration of series and parallel wiring is often the optimal solution.
Through careful planning, you — or a licensed installer — can achieve the right balance of voltage and amperage by combining series and parallel wiring.
Working with a professional installer carries additional upfront costs, but solar is a long-term investment.
Maximising the performance of your PV system will substantially increase your return on investment and reduce the solar payback period.
Hybrid parallel/series wiring is complex, and it’s not recommended that you attempt it on your own.
Save yourself time and money in the long run — work with a reputable installer.
An optimal wiring plan will consider the following factors:
- Electricity output requirements
- Rated power, type, and number of PV modules
- Average hours of peak sunlight at your location
- Optimal position, angle, and direction of the solar panel installation
- Fixed obstructions to direct sunlight)
- Average temperatures at your location
Unless you only need a portable solar generator, like EcoFlow DELTA 2 Max, working with the right installer from the outset can help you make an informed purchase decision.
Low Irradiance and Voltage Drop
Even the best solar generators can’t thrive without the proper environmental conditions. That’s why keeping your panels out of the shade and clear of obstructions (like snow) as much as possible is essential. If you are dealing with low irradiance, i.e., low light conditions, it could cause the voltage of your equipment to drop. And when it drops to a certain level, you may not be able to generate power at all.
All batteries or portable power stations require a minimum voltage to charge. The whole system is relatively useless when the panels fail to meet that minimum voltage.
Parallel-wired systems often run the risk of voltage drop. The reason is that the voltage is relatively low, to begin with, since the amperage increases, not the voltage, as you connect panels in parallel. Therefore, if conditions aren’t ideal, like in a low irradiance situation, you may swiftly be dealing with voltage drops. A hybrid or series wiring system could help solve this issue.
Additionally, you must minimize any risk of shading or low irradiance. Keeping the surface of your panels clean can also make a difference here! If shade or tree cover is unavoidable, it may be better to invest in portable solar panels rather than ones that require roof installation.
Voltage & Amps of Solar Panels Wired Series vs. Parallel
To understand why wiring PV modules in series or parallel matters, a basic grasp of what volts and amps mean in electricity is essential.
- Volts (V) measure electrical potential or force
- Amperes (amps) measure electric current.
A simple way to think about the relationship between volts and amps is to compare them to a garden hose.
Voltage is the pressure that pushes water through a hose and amperage measures how fast the water flows.
When you wire in series, you combine the electrical pressure (voltage) of all of your panels while the rate of flow (amperage) remains constant.
On the flip side, when you wire in parallel, the amps add up, but the voltage does not.
You increase the flow rate but not the pressure.
When deciding if you’re going to wire in series or parallel, it’s essential to pay attention to the voltage and amperage of all panels and the requirements and limits of your balance of system, such as your inverter, solar battery, and charge controller.
That way, you can identify the best way to wire your array to optimise power generation without exceeding the maximum that your solar power system can handle.
Solar Panel Wiring Using a String Inverter
When shopping for a solar panel system, there are three primary types of solar inverters you may encounter.
- String inverter
- Microinverters
- Central inverters
As we’ve discussed, the voltage increases with series wiring while the current remains constant.
String inverters are designed to tolerate the high voltage produced by multiple PV modules wired in series.
Many string inverters can handle the combined output voltage of multiple series-connected solar panels at a lower cost than other inverter types.
Most residential solar panel arrays require only one string inverter.
However, using a string inverter and PV panels you connect in series can be problematic if you don’t have consistent access to unobstructed sunlight.
A string of series-wired panels is only as strong as the weakest link.
Any shade or damage that affects one of the panels drives down the efficacy of the entire array.
Additionally, be aware of the risks associated with string inverter setups.
The high voltage achieved when wiring PV modules in series makes severe electrical events — like fire or arc-faulting — more likely than with parallel connections.
Frequently Asked Questions
If you connect two identical solar panels together in series or parallel under laboratory conditions, the electricity output using either method will be virtually identical. Neither wiring method is “better,” only optimal for your specific application and external conditions. A hybrid series-parallel wiring plan made and executed by a professional installer is likely to yield optimal production for large residential solar installations.
Yes, you can wire solar panels in series or parallel. In some cases, you can even wire solar panels in both series and parallel simultaneously. For example, if you have two panels with 12V each, wire them in series to start. Then, assuming you have another 24V panel, you can wire them together in parallel. Assess your solar situation and how much sunlight you can access, then choose which wiring method will fit your needs the best.
Solar panels don’t need to be identical to be wired effectively. However, connecting modules with different electrical ratings makes planning more difficult. If you’re wiring in series, all your panels should have the same current rating. Otherwise, the current output will only equal the lowest rating in the series. Similarly, parallel wired systems should have consistent voltage. If not, the system output will match only the lowest output rating. If you connect solar panels from different manufacturers, compatibility is the main thing to check for.
It’s technically possible to mix 12V and 24V solar panels. But it’s not ideal. It’s best to opt for panels with as similar specs as possible. If you must use equipment with mixed power ratings, wire two 12V panels together in series before wiring them in parallel to their 24V counterpart. It’s always best to choose the wiring technique that makes the most sense for the specs of your equipment.
No. Connecting solar panels in serial or parallel does not impact how much wattage they produce in laboratory conditions. Connecting solar panels in parallel increases amperage and keeps voltage constant. Series connections produce higher voltage while maintaining amperage, regardless of how many panels you use. Depending on external factors, either method may be optimal. For large residential installations, a hybrid serial-parallel wiring plan is often best.
Yes. As long as you don’t exceed the maximum solar input of your portable power station, solar inverter, or solar battery charge controller, you can add more solar panels to meet your electricity production needs. It’s common for people to underestimate their electricity consumption. If you think it’s likely that you’ll want to add to your PV array as time passes, opt for a balance of system with sufficient capacity to accommodate growth.
Yes. If you have more than one 12V panel, you can connect them in series to combine their output voltage. When you wire in series, you add the voltage of each panel together. If you connect 2 x 12V panels, you get total output voltage of 24V. Make sure the combined voltage doesn’t exceed the maximum input capacity of your solar inverter or charge controller.
In small systems, e.g., two solar panels and a portable power station for an RV, connecting panels in parallel will likely result in slightly faster recharge times. A series or a hybrid of series-parallel connections might be optimal for whole-home battery backup. Which wiring method provides the shortest charging time for solar batteries is not dependent on whether it’s series or parallel – it’s dependent on external factors.
When wiring multiple photovoltaic modules together, it’s essential to consider the specs of each panel. You can solar wire in series, parallel, or a hybrid configuration of both to achieve optimal results. When you wire in series, you add the voltages together. When you wire in parallel, you combine the amps.
Final Thoughts
No matter what stage of load-shedding you’re at in your area, Eskom’s power grid has proven unreliable again and again.
With solar panels and generator costs rapidly decreasing, renewable energy technology is now accessible to almost everyone.
With careful planning, you can optimise your solar panel wiring with series or parallel connections — or a hybrid of both.
Take control of your home energy security during rolling and unscheduled blackouts.
Check out EcoFlow’s home backup power and solar solutions today.