How to Wire Solar Panels in Series & Parallel

There are two options for connecting many solar panels in a system: series and parallel wiring. Wiring solar panels in series or parallel is a decision that should be made based on the intended use. Let’s break it out and see when each approach works.

Series vs. parallel connection: Explain the Differences

The output voltage and current are the primary determinants of whether solar panels are wired in series or parallel. Wiring solar panels in series increases the total output voltage while maintaining the same output current from each individual panel. When many solar panels are connected in parallel, the output currents sum up, but the voltages remain constant. Let’s take a deeper dive into the inner workings of this and learn how to properly wire solar panels in parallel or series.

Series-Connecting Solar Cells

To wire solar panels in series connect the first solar panel’s positive terminal to the second panel’s negative terminal, and so on. The total voltage will be equal to the sum of the individual voltages of the panels connected in series. The overall current will, however, be identical to the current generated by a single panel. Three 5-ampere, 20-volt panels, for instance, are connected in series. The output current remains at 5 amps despite the 60-volt voltage (20V * 3 = 60V).

Parallel Wiring of Solar Panels

To wire solar panels in parallel.Connect the positive terminals of all of the solar panels together, and then link the negative terminals of all of the solar panels together. The total amperage drawn from the array of panels is equal to the sum of their individual ratings. The combined voltage, however, will be the same as the circuit voltage produced by a single panel. For instance, we have three parallel-wired 5-amp, 20-volt solar panels. Despite having a total output current of 15 amps (5A * 3= 15A), the voltage is still 20 volts.

What’s Optimal, Connecting Solar Panels in Series or Parallel?

At this point, we may discuss whether series or parallel wiring is preferable for solar panels. Which is better, wiring solar panels in series or parallel? Again, it all comes down to the specifics of your request. If you plan on spending the vast majority of your time in sun-drenched areas, wire solar panels in series is likely to provide the best results. The primary rationale for this is that your solar panel system will be more productive and efficient before sunrise, after sunset, and during gloomy weather. Here is the reason.

To charge a battery, you need to use a greater voltage than the battery’s normal voltage. Our lithium-ion batteries, for instance, need about 15 volts to begin charging. The output voltage of most 100-watt solar panels is slightly lower than 20 volts. Parallel solar panels would need to be working at 75% or higher to produce 15 volts, the minimum voltage needed to charge your batteries.

If you have three identical cells, wiring solar panels in series, however, would result in an output voltage of around 60 volts. This would reduce the amount of power your solar panels produce by around a quarter, allowing them to still charge your batteries. Late in the day or on overcast days, it is significantly simpler to operate at 25% capacity. Remember that if you want to wire solar panels in series an MPPT charge controller is required for such a setup to function properly.                             

Parallel wiring solar panels is not always a bad idea. MPPT charge controllers are costly and may be unnecessary for lightweight, portable uses. A camper van or boat with a modest low-voltage system and potentially varying lighting conditions might benefit from a system where you wire solar panels in parallel. You may save some cash and get excellent performance from your system by using a PWM charge controller.

How To Choose Between Series And Parallel For Mixing Panel Types

We have always assumed that identical solar panels will be used in all of our cases. This is highly recommended and the best course of action, but it is not necessary. It is feasible to use solar panels from various manufacturers with differing electrical ratings, but doing so requires adhering to several important principles:

  • All of the solar cells in your array should have the same current rating if you want wiring solar panels in series. Although the voltages will still add up, the current output will be limited to that of the panel with the lowest rating in the series.
  • On the other hand, if you want wiring solar panels in parallel, each panel must have the same voltage rating. In this case, the lowest-rated panel will determine the system’s output voltage.

Each array connected to a charge controller should have the same kind of panels installed. The best way to maximize solar output while employing a variety of solar panel types is to use several charge controllers, one for each separate panel array.

Series vs. Parallel: Which Situations Call for Series and Parallel Wiring of Solar Panels?

There is no definitive answer as to whether solar panels should be wired in series or parallel. The two choices of wiring solar panels each have advantages and disadvantages. Your requirements and intended use should guide your choice. Connect your solar panels such that the voltage range your inverters can handle is within its operational window. Here are the pros and cons of both methods.

Wire Solar Panels in Series Pros:

  • No additional materials or tools are needed.
  • Reduces the amount of current (amps) so that thinner gauge wire may be used.
  • Beginning and ending the day are the best times to use a series string.

Wire Solar Panels in Series< Cons:

  • Doesn’t do well when partially shaded; the output of a series-connected array reduces when even a single panel is shaded.

Wire Solar Panels in Parallel Pros:

  • Performs well in shadow; if one panel in a parallel array is shaded, the others will still produce energy as usual.

Wire Solar Panels in Parallel Cons:

  • Needs nodes to link branches.
  • The solar panels could need fusing.
  • Boosts current, necessitating the use of more costly, thicker cables and devices rated for greater electrical loads.
  • Not as effective in the early or late hours of the day.

If you wire solar panels in parallel and series into a series-parallel design, this is often the best choice for bigger solar arrays.

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