Use our solar panel series and parallel calculator to easily find which common wiring configuration maximizes the power output of your solar panels.
Solar Panel Series & Parallel Calculator
How to Use This Calculator
1. Find the technical specifications label on the back of your solar panel.
Note: If your panel doesn't have a label, you can usually find its technical specs in its product manual or on its online product page.
2. Enter the panel's max power voltage (denoted Vmp or Vmpp). It may also be called the optimum operating voltage.
3. Enter the panel's max power current in amps (denoted Imp or Impp). It may also be called the optimum operating current.
4. In the Quantity field, enter the number of this type of solar panel you'll be wiring together.
5. If you're using different solar panels, click "Add a Panel" and fill out the next panel's specs and quantity. Repeat this process as many times as needed. You can click "Remove a Panel" at any time to remove the last panel added.
6. Once you've added all your panels, click “Calculate Series vs Parallel Wiring Outputs” to compare the power outputs of common wiring configurations.
About This Calculator
- The wiring configurations given may not include the optimal wiring configuration for your system. (If any smart programmers out there have some ideas on how to always find the optimal configuration, please send me a message.)
- This calculator does not calculate your array's maximum open circuit voltage, which is needed when sizing your charge controller. For that, check out our solar panel voltage calculator.
How to Calculate Solar Panel Output of Series & Parallel Wiring Configurations
Here's how to calculate the power output of your solar array, regardless of how you're wiring your panels together -- and regardless of whether or not the panels are identical.
Series
Identical Solar Panels
For identical solar panels wired in series, the voltages are summed and the current stays the same.
For example, let's say you have 3 identical solar panels. All have a voltage of 12 volts and a current of 8 amps. When wired in series, the 3 connected panels (often called a series "string") will have a voltage of 36 volts (12V + 12V + 12V) and a current of 8 amps. In this example, the series string will have no losses.
Different Solar Panels
For mismatched solar panel wired in series, the voltages are summed and the current is equal to that of the lowest-rated panel.
For example, let's say you have 3 different solar panels with the following specs:
- 12V, 8A
- 14V, 7A
- 16V, 6A
When wired in series, the resulting series string will have a voltage of 42 volts (12V + 14V + 16V) and a current of 6 amps (the lowest current rating of the 3 panels).
In this example, our series string will have some power losses because the currents of the 12V/8A panel and 14V/7A panel will get "pulled down" to 6 amps.
Parallel
Identical Solar Panels
For identical panels wired in parallel, the currents are summed and the voltage stays the same.
For example, let's go back to the scenario of 3 identical solar panels, all with a voltage of 12 volts and a current of 8 amps. When wired in parallel, the 3 connected panels will have a voltage of 12 volts and a current of 24 amps (8A + 8A + 8A). In this example, our parallel string will have no losses.
Different Solar Panels
For mismatched solar panels wired in parallel, the currents are summed and the voltage will be equal to that of the lowest-rated panel in the string.
For example, let's say you have 3 different panels with the following specs:
- 12V, 8A
- 14V, 7A
- 16V, 6A
When wired in parallel, the resulting parallel string will have a voltage of 12 volts (the lowest voltage rating of the 3 panels) and a current of 21 amps (8A + 7A + 6A).
In this example, our parallel string will have some power losses because the voltages of the 14V/7A panel and 16V/6A panel will get pulled down to 12 volts.
Series-Parallel
Identical Solar Panels
For identical solar panels wired in a series-parallel configuration, for each series string the voltages are summed and the current stays the same. Then, for each series string of identical length wired in parallel, the currents are added and the voltage stays the same.
For example, let's say you have 4 identical solar panels, all with a voltage of 12 volts and a current of 8 amps. First, you wire 2 sets of 2 panels in series to create 2 series strings of 24 volts (12V + 12V) and 8 amps. Then, you wire both series strings in parallel to create a 4-panel array of 24 volts and 16 amps (8A + 8A).
When using identical solar panels, it's important your series strings be identical length. If they aren't, the voltages of the strings will be different.
Generally, I recommend wiring solar panels in series first, then parallel. This limits the number of branch connectors needed and can reduce your wiring costs.
Different Solar Panels
For different solar panels wired in a series-parallel configuration, for each series string the voltages are summed and the current will be equal to that of the lowest-rated panel in the string. Then, when the series strings are wired together in parallel, the currents are summed and the voltage will be equal to that of the series string with the lowest voltage rating.
For example, let's say you have 4 different solar panels with the following specs:
- 12V, 8A
- 16V, 6A
- 14V, 7A
- 20V, 5A
First, you wire the 12V/8A panel and 16V/6A panel in series to create a series string with a voltage of 28 volts (12V + 16V) and a current of 6 amps (the lowest current rating of the 2 panels).
Next, you wire the 14V/7A panel and 20V/5A panel in series to create a second string with a voltage of 34 volts (14V + 20V) and a current of 5 amps (the lowest current rating of the 2 panels).
Finally, you wire the 2 series strings in parallel to create a 4-panel solar array with a voltage of 28 volts (the lowest voltage rating of the 2 strings) and a current of 11 amps (6A + 5A).
Unfortunately, when dealing with mismatched solar panels in a series-parallel setup, there's no simple rule I can give for easily finding the wiring configuration that will result in the greatest power output. Our calculator at the top of this page is a good starting point, but it may not give the optimal configuration.
In these situations, I recommend trial and error. Calculate the output of multiple wiring configurations and go with the one that results in the greatest power output.
Wiring Solar Panels in Series or Parallel: Which Is Best?
Here's a quick breakdown of when to use series or parallel wiring for your solar panels.
Series
Pros
- No need to buy any extra equipment
- Keeps current low, helping you save money on wiring costs
Cons
- Doesn’t work well in shade — when a single panel in a series configuration gets shaded, the power output of the entire array drops
When to Use
- Your solar panels will spend most of their time unshaded
- You want to save on wire and equipment costs
- You’re using an MPPT charge controller
Parallel
Pros
- Works better in shade — when a panel in a parallel configuration gets shaded, the remaining panels will continue to output power as expected
Cons
- Requires buying branch connectors
- May need to fuse the solar panels
- Increases current — you may need to buy thicker, more expensive wire, and equipment with higher current ratings
When to Use
- Your solar panels spend most of the time in the mixed-light conditions
- You’re using a cheaper PWM charge controller
How to Wire Solar Panels in Series & Parallel
Here's a quick overview of how to wire solar panels in series and parallel. For more in-depth instructions, check out our full tutorial.
Full tutorial: How to Wire Solar Panels in Series & Parallel
Series
To wire solar panels in series, connect the positive cable of one to the negative cable of the other.
Here's a video showing you what I mean:
That's it!
If you want to connect more in series, just connect the positive cable of each additional solar panel to the negative cable of your series string. You can string together as many panels as you want like this.
Parallel
To wire solar panels in parallel, you need to buy the appropriate branch connectors for the number of panels you're wiring in parallel. (You may also need to buy inline MC4 fuses and connect them to the positive cable of each solar panel.) I'll show you how to wire 2 panels in parallel using Y branch connectors.
To do so, connect the 2 positive solar panel cables to the compatible Y connector. Then connect the 2 negative solar panel cables to the other Y connector.
Here's a video showing how to do this:
If you're wiring more than two solar panels in parallel, pick the right branch connector for the number of panels you'll be wiring in parallel.
H/T to Mowgli Adventures whose calculator was a big inspiration for this one. Their blog is amazing and you should definitely check it out!
