How to Wire Solar Panels in Series or Parallel

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When you start thinking about solar options for your home, it’s easy to get confused by all the technical terms you may read or hear. You may come across different ways of wiring solar panels. And your first thought may be: does it really matter? After all, all you want is for the panels to generate electricity.

How you wire the solar panels is important. It influences the performance of the system, as well as the solar inverter that you will be able to use. What you really want is to have your panels wired in a way that gives you the most savings and the best return on investment.

Today we are talking about the wiring of solar panels, we will try to better understand if you are interested in connecting your panels in series or in parallel.


What does it mean to wire solar panels in series?

Like a battery, solar panels have two terminals: a positive and a negative.

When the positive terminal of one panel is connected to the negative terminal of another panel, a series connection is created. When you connect two or more solar panels like this, it becomes a photovoltaic source circuit.

When solar panels are connected in series, the voltage of the panels adds up, but the amperage remains the same. So, if you connected two solar panels with a rated voltage of 40 volts and a rated amperage of 5 amps in series, the series voltage would be 80 volts, while the amperage would remain at 5 amps.

The series connection of the panels leads to an increase in the voltage of the network. This is important because a solar power system must operate at a certain voltage for the inverter to work properly.

Therefore, you connect your solar panels in series to meet the inverter requirements.

What does it mean to wire solar panels in parallel?

When solar panels are connected in parallel, the positive terminal of one panel is connected to the positive terminal of another panel and the negative terminals of the two panels are connected together.

The positive wires connect to a positive connector inside a junction box, and the negative wires connect to the negative connector. When multiple panels are connected in parallel, it is called a PV output circuit.

Wiring the solar panels in parallel increases the amperage, but the voltage remains the same. So if the same panels as before are connected in parallel, the system voltage will still be 40 volts, but the amperage will increase to 10 amps.

Parallel wiring allows you to have more solar panels producing power without exceeding the inverter’s operating voltage limits. Inverters also have amperage limitations, which you can respect by connecting your photovoltaic panels in parallel.

How do series wired solar panels compare to parallel wired solar panels?

The charge controller is a determining element for the wiring of the solar panels. Maximum Power Point Tracking (MPPT) charge controllers are used to wire solar panels in series, while PWM technology controllers are used to wire solar panels in parallel.

To understand how series wiring works versus parallel wiring, let’s think for a moment about how Christmas lights work.

If a bulb burns out, comes loose from its socket, or breaks, the entire string will not light up. This was because the lights were connected in series. The problematic bulb had to be located and replaced or reinstalled to get the light string working again.

Today, most Christmas lights feature a type of parallel wiring that allows strings of lights to stay on even when there is a problematic bulb in the string.

Series-wired circuits work the same way for solar panels.

If there is a problem with connecting a panel in series, the whole circuit fails. On the other hand, a defective panel or a loose cable in a parallel circuit will not affect the production of the rest of the solar panels.

In practice, the wiring of solar panels today depends on the type of inverter used.

Wiring the solar panels when using a string inverter.

String inverters have a rated voltage window that they need from the solar panels to operate. They also have a current rating that the inverter needs to work properly.

String inverters have maximum power point trackers (MMPTs) that can vary current and voltage to produce the maximum amount of power possible.

Are the solar panels connected in series or in parallel?

In most crystalline solar panels, the open circuit voltage is around 40 volts. Most string inverters have an operating voltage window between 300 and 500 volts. This means that when designing a system, you might have between 8 and 12 panels in series.

More than that would exceed the maximum voltage the inverter could handle.

The thing is, most solar panel systems are larger than 12 panels. Therefore, to get more panels in the system, you can wire another series of panels and connect these series in parallel. This allows you to have the right number of panels to meet your home’s energy needs, without exceeding inverter limits.

Which is better, wired in series or in parallel?

In theory, parallel wiring is a better option for many electrical applications because it allows continuous operation of the panels, even if one of them malfunctions. But it’s not always the best option for all applications. You may also need to meet certain voltage requirements for the inverter to work.

It is necessary to achieve a balance between voltage and amperage for the solar generator to work best. Therefore, in most cases, a solar installer will design your installation with a hybrid of series and parallel connections.

Can you add more solar panels?

An installation designed from the ground up is always best when installing a solar home system. Using a solar calculator helps estimate the costs and energy needs of your solar system to accurately determine how many panels your photovoltaic system should have.

However, if you had a limited budget or miscalculated your energy needs when installing your PV system, you might consider adding more panels to your already installed system.

If you plan to expand your solar PV system in the future, you should design your system with this in mind. In order to accommodate more panels in the future, you should have an oversized inverter.

Does the use of microinverters or optimizers change the way solar panels are wired?

Using microinverters or optimizers in your solar system design can help avoid the inverter size limitations that string inverters have. By connecting each panel to its own microinverter, your system can scale from panel to panel.

This can be done with existing string inverters that are maxed out, as long as the additional panels are connected to the AC side of the string inverter.

How are solar panels connected to the grid?

Another consideration between series wiring and parallel wiring is the number of wires used to connect the solar system to the grid. A series-wired circuit will use a single wire to connect. Instead, a parallel wired system will have multiple wires to connect it to the network.

Series or parallel: why not have both?

The main thing to remember is that wiring in series will increase voltage, while wiring in parallel will increase amperage. Voltage and amperage should be considered when designing your system, especially when it comes to finding the best solar inverter for your system.

Most of the time, a solar installer will choose to design a system with series and parallel connections. This allows the system to operate at higher voltage and amperage, without overloading the inverter, so your solar panels can operate at their full capacity.


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