When to Connect Solar Panels in Series and When to Connect Them in Parallel
Before we dive into when to connect solar panels in series or parallel, the first thing to know is that every solar panel has two terminals: one positive and one negative. If you’re eager to fully understand how these connections work and want a more detailed explanation, we have an in-depth guide on our website that you can check out.
Series or Parallel: It Depends on Your Inverter or UPS
The choice between connecting solar panels in series or parallel depends on the rating of your inverter or UPS. As you might already know, there are two main types of inverters/UPS systems:
- 12V operated inverters/UPS
- 24V operated inverters/UPS
Understanding the Wattage of Solar Panels
Similarly, solar panels come in different wattages, and these wattages will guide how they are connected:
- Solar panels in the 150W to 180W range are typically designed for 12V systems.
- Panels ranging from 250W to 330W are designed for 24V systems.
Connecting Solar Panels in Parallel for 12V Systems
When your inverter or UPS is 12V, you’ll need to connect all your solar panels (those designed for 12V) in parallel. In a parallel connection, the voltage remains the same while the current (amps) increases.
Connecting Solar Panels in Series for 24V Systems
If your system operates on 24V—such as when you have a double battery setup—you’ll need to connect two solar panels in series to create a 24V system. In this case, two 12V panels connected in series will combine their voltages to give you 24V.
Combining Series and Parallel for Larger Setups
After setting up your two panels in series to achieve 24V, you can connect additional series connections in parallel to keep the voltage at 24V while adding current. In larger setups, you may need to use a 60A connector strip to ensure proper connections.
Important Tip: Use Proper Connector Strips, Not Tape
A quick tip: when connecting your solar panels, don’t use tape to secure the connections. Instead, use connector strips that follow proper rules and regulations. Not only does this ensure safety, but it also gives the installation a clean, professional look. Each panel typically has an output of around 20V, but we often refer to them as 12V panels because most charge controllers (or built-in ones in UPS systems) step the voltage down to 12V.
How to Make Your Solar Connections Step-by-Step
Step 1: Preparing for a 12V Output
Let’s say we want a total output of 12V because our UPS is also 12V. To do this:
- First, connect the positive and negative terminals of two solar panels.
- Then, take the output of both panels using two wires and connect them to the UPS.
Step 2: Connecting Solar Panels in Parallel
After connecting the panels, you will take the two output wires and route them to the UPS. This setup creates a circuit where the two wires coming from each solar panel are connected through their respective junction boxes.
Step 3: Modifying the Solar Panel Connectors
The next step is to cut off the plastic connectors from the solar panel junction boxes and replace them with connector strips. This way, you can use just two connectors from the strip.
Proper Wiring for Solar Panels
Step 1: Combining Positive and Negative Wires
To start, twist the positive wires together in one connector and the negative wires in another. Secure them properly in the connector strip. This is where your wiring begins to take shape.
Step 2: Using the Right Wire for the Job
For extracting the output from the panels, use an 8mm pure copper wire. While a 6mm wire could be sufficient for smaller setups, we recommend 8mm for future expansion. This is especially important if the system’s current might exceed 40 amperes.
Step 3: Protecting the Wires from the Weather
Since your solar panel wires will be exposed to the elements, protect them with a plastic pipe. This will help prevent sun damage and ensure your system lasts throughout the year, no matter the weather.
Final Steps in Your Solar Panel Setup
Step 1: Securing the Connections
When wiring is completed and the output is secured, mount the connector on the lower side of the solar panel. Use ties to ensure everything is held firmly in place. Repeat the same process for the other panels, making sure to correctly connect the positive and negative terminals.
Step 2: Routing the Wires to Your Inverter or UPS
Once the connections are made, route the two wires from the connected solar panels to the UPS or inverter. Make sure the wires are neatly organized and pass through conduits or pipes to protect them.
Step 3: Connecting All Panels Together
After wiring the two solar panels, join them with the total output wires of the system. Attach these two solar panels, and now the connection of the positive terminals will be complete. Repeat the process for the negative terminals.
Step 4: Ensuring Proper Current Flow
At this point, the current from all the panels will pass through the wire and pipe system, heading to your inverter or UPS. The final step is to check the voltage and current coming from the entire system.
Testing the Output
Step 1: Checking the Voltage
Once everything is connected, check the voltage at the output terminal. It should be around 20.21V. Since the panels are connected in parallel, the voltage will stay the same (around 20V) for all panels.
Step 2: Measuring the Current
Now, check the total current. We measured around 30.59 amps, meaning the four panels together were generating approximately 31 amps. On days with less sunlight, each panel produces around 7.5 amps, but on sunny days, they can produce up to 8 or 9 amps each.
Final Touches and System Integration
Step 1: Tidying Up the Wiring
Once everything is connected, make sure the wires are neatly dressed and routed through the pipe system. This keeps things tidy and safe from the elements.
Step 2: Completing the Installation
Finally, route the solar wires through the proper ducting or holes to reach the inverter or UPS. Once connected, your system will be complete, and your solar panel wiring will be fully set up and ready to go.
