When wiring multiple solar panels, you can choose between series or parallel configurations based on your application. Let’s explore the differences and ideal uses for each method.
What’s the Difference? Solar Panels: Series or Parallel
The wiring of your solar panels affects system performance and inverter compatibility.
When you wire multiple panels in series, it increases voltage while keeping current the same, helping meet the inverter’s minimum operating voltage.
In contrast, parallel wiring for solar panels boosts current without changing voltage, enabling energy production within the inverter’s limits.
Let’s examine how to wire panels in both configurations.
Series Solar Panel Wiring
Voltage and Amps in Series
Connecting the positive terminal of one panel to the negative terminal of another creates a series connection. This configuration sums all panel voltages, but the total current remains equal to that of a single panel.
The graphic above shows four 12-volt, 5-amp panels wired in series. The output voltage is 48 volts (12V*4 = 48V), yet the output current is still 5 amps.
What It’s Best For
Solar panels in series perform best in unshaded conditions. If one panel is shaded, it reduces the entire system’s power output.
Solar panels in series are ideal for low-amperage systems because higher voltage results in lower amperage, allowing for smaller and cheaper wires.
When wiring your panels in series, you must use an MPPT charge controller. MPPT controllers adjust the voltage and current from the solar panels to match the battery bank’s voltage without losing power. If you use a PWM controller, the battery will lower the total panel array voltage, resulting in significant power loss.
Parallel Solar Panel Wiring
Voltage and Amps in Parallel
To wire solar panels in parallel, connect all positive terminals together, as do the negative terminals. The resulting current will equal the sum of all panel amperages, while the total voltage will match the one panel’s output voltage.
When multiple panels are wired in parallel, it forms a PV output circuit.
The graphic above shows four 12-volt, 5-amp panels wired in parallel. The output current is 20 amps (5A*4 = 20A), yet the output voltage is still 12 volts.
What It’s Best For
Solar panels in parallel operate independently, making them great for mixed-light conditions. If one or two panels are shaded, the others will still generate power.
They are also suitable for low-voltage systems with less expensive PWM controllers, as wiring in parallel does not change the total output voltage. This setup allows you to increase charging current without needing to regulate voltage, provided the panel output matches the battery charging voltage.
Solar Panels: Series or Parallel, Which is Better?
Now that we understand the differences between wiring solar panels in series and parallel, let’s discuss which is better for your application.
Wiring panels in series is often ideal if you can keep them mostly unshaded. This setup improves efficiency, especially during low-light conditions like early morning or cloudy days.
Higher voltage is needed to charge batteries; for example, our lithium batteries require 14.4 volts to start charging. Most 100-watt panels output 18-20 volts, so wiring them in parallel requires operating at over 75% capacity.
In contrast, connecting three of these panels in series produces 54-60 volts, allowing the array to operate at just around 25% capacity for effective charging – much easier even late in the day or on cloudy days. Note that an MPPT charge controller is necessary for this system.
However, wiring in parallel isn’t a bad option either. MPPT controllers are expensive and may be excessive for small setups like RVs or boats with variable lighting conditions. In such cases, a parallel system could work well with a lower-cost PWM charge controller, saving you money.
Series or Parallel For Mixing Panel Types
You can mix solar panels from different manufacturers, but the conditions differ for series and parallel configurations.
Mismatched solar panels in series operate at the lowest amp. In our first example, if you replace one panel with a four-amp panel, the entire system will output four amps.
In parallel wiring, it increases the amps while keeping the voltage the same.
Conclusion
There is no definitive answer for wiring solar panels in series or parallel, as both have benefits and drawbacks. Wiring in series increases voltage, while wiring in parallel increases amperage. The choice depends on your specific needs and application.
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