When setting up a solar power system, understanding how to wire your panels is crucial for optimizing performance and ensuring safety. The way you connect your solar panels directly impacts the voltage and current output of your system.
In this post, we will break down the three primary wiring configurations: series, parallel, and series-parallel. We also made a video tutorial that you can watch on our official YouTube channel here:
The How and Why: Wiring Solar Panels in Series, Parallel, and Series-Parallel | RICH SOLAR TALK
We will use custom-made 35W solar panels for our example. Each panel has a Voc (Open Circuit Voltage) of 21.6V and an Isc (Short Circuit Current) of 2.13A. You can usually find these specs on the back of your solar panel.
Wiring in Series
In a series connection, you connect the positive terminal of one solar panel to the negative terminal of the next panel in a string. The string will act as one large solar panel in a sense.
In the image above, the negative terminal of Panel 1 is connected to the positive terminal of Panel 2, creating a series string.
When panels are wired in series, the voltage adds up, while the amperage remains the same. This is ideal for systems that require a higher voltage to activate.
When we connect four 35W Solar Panels in Series:
- Total Voltage: 21.6V (Panel 1) + 21.6V (Panel 2) + 21.6V (Panel 3) + 21.6V (Panel 4) = 86.4V
- Total Amperage: 2.13A
The image above shows four panels connected in series.
Pros of Series Wiring:
- Higher Voltage for Longer Distances: Higher voltage reduces current, which in turn reduces voltage drop over long cable runs, allowing for thinner gauge wires and less power loss.
- Easier Wiring: This way of wiring doesn’t require additional adapters to configure, as it is a simple daisy-chain of positive to negative connections in the string.
Cons of Series Wiring:
- Shading Impact: If even one panel in a series string is shaded, it significantly reduces the output of the entire string. The shaded panel acts as a bottleneck, limiting the current flow for all panels.
- Chance of Exceeded VDC Rating of your Controller: When you produce a higher voltage with your string of panels in series, please keep in mind the VDC rating of your solar charge controller.
Wiring in Parallel
In a parallel connection, you connect all the positive terminals of the solar panels together and all the negative terminals together using parallel adapters. All of the panels will now act independently of each other, unlike in series wiring.
In the image above, two positive terminals and two negative terminals from two solar panels are connected using Y-branch 2-to-1 Parallel Adapters. These adapters can be found here.
When panels are wired in parallel, the amperage adds up, while the voltage remains the same.
When we connect four 35W Solar Panels in Parallel:
- Total Voltage: 21.6V
- Total Amperage: 2.13A (Panel 1) + 2.13A (Panel 2) + 2.13A (Panel 3) + 2.13A (Panel 4) = 8.52A
In the image above, four solar panels are connected in parallel using a Y-branch 4-to-1 Parallel adapter. This adapter can be found here.
Pros of Parallel Wiring:
- Better Shading Tolerance: If one panel is shaded in a parallel array, the other panels continue to produce power at their full potential, as they are not directly dependent on the shaded panel's current.
- Higher Amperage for Battery Charging: Parallel wiring provides more amperage (current), which can be beneficial for charging lower-voltage battery banks quickly.
- Redundancy: If one panel fails, the rest of the array can still produce power.
Cons of Parallel Wiring:
- Higher Amperage Requires Thicker Gauge Cables: The increased current flow in parallel arrays necessitates thicker gauge wiring to prevent excessive voltage drop and overheating.
- Fuse/Breaker Requirements: Each parallel string may require its own fuse or breaker to protect against overcurrents and ensure safety.
Wiring in Series-Parallel (Combined)
The series-parallel configuration combines the advantages of both series and parallel wiring. This is often used in larger systems to achieve a desired voltage and amperage balance.
How it Works:
You create multiple series strings and then connect those strings in parallel.
Example (Four 35W panels):
Let's create two series string of two panels.
-
Series 1:
- Voltage: 21.6V + 21.6V = 43.2V
- Amperage: 2.13A
-
Series 2:
- Voltage: 21.6V + 21.6V = 43.2V
- Amperage: 2.13A
Now, connect Series 1 and Series 2 in parallel.
- Total Voltage: 43.2V (voltage remains the same when series strings are in parallel)
- Total Amperage: 2.13A (Series 1) + 2.13A (Series 2) = 4.26A
In the image above, two panels are connected in series, and another two panels are connected in series, creating two strings: Series 1 and Series 2.
In the two images above, Series 1 and Series 2 were connected using Y-branch 2-to-1 Parallel Adapters. These adapters can be found here.
Pros of Series-Parallel Wiring:
- Balanced Output: Offers a good balance between voltage and amperage, making it versatile for various system requirements.
- Improved Shading Performance (compared to pure series): While shading on one panel in a series string still impacts that string, the other parallel strings will continue to perform.
- Optimized for Charge Controllers: Can provide a suitable voltage range for charge controllers while still allowing for a good amount of current.
Cons of Series-Parallel Wiring:
- More Complex Wiring: Requires a more intricate wiring setup compared to simple series or parallel connections.
- Requires More Connection Points: Leads to more connections, increasing the potential for loose connections if not installed carefully.
Choosing the Right Configuration
The best wiring configuration for your solar panels depends on several factors:
- System Voltage Requirements: What is the operating voltage of your inverter or charge controller?
- Battery Bank Voltage: If you have a battery bank, what is its nominal voltage (12V, 24V, 48V)?
- Shading Conditions: Is your installation location prone to partial shading?
- Cable Lengths: How far are your panels from your charge controller or inverter?
We hoped this post helped you figure out what is the best wiring method for your solar system. Please reach out to our tech team at tech@richsolar.com if you have further questions about your RICH SOLAR panels.
Have a solar day!