How To Wire Solar Panels to Breaker Box In Parallel vs. Series (& How To Choose)

Georgette Kilgore headshot, wearing 8 Billion Trees shirt with forest in the background.Written by Georgette Kilgore

Solar Panels | April 1, 2024

Woman looking at solar panels wired together in series wonders how to wire solar panels to breaker box during solar panel installation and if there is a wiring diagram for solar panels showing how to wire solar panels in parallel.

Solar panel installation can seem daunting, especially if someone does not know how to wire solar panels to breaker box in parallel vs. series, or how to choose them.

Having all of the information up front is crucial, because this is a serious DIY project. In fact, many counties and municipalities require a licensed electrician to sign off on the connection, if you do it yourself.

But, all homeowners with solar systems should understand how to wire solar panels to a breaker box.

Solar power is among the most natural and most recommended power sources out there, and when used in residential applications to remove yourself from the grid, it can be highly effective.

Why is sustainable use of natural resources important? Proponents of sustainable development argue that renewable energy is the best way to combat climate change, but massively large fields of solar panels have their own ecological drawbacks.

This is why when choosing solar for your home, you’re reducing your carbon footprint without significant damage to the ecosystem.

This guide systematically explains the solar panel installation process using steps, provides a solar panel installation diagram, illustrates the difference between parallel vs. series installations, and provides safety tips on successfully installing solar panels in your home or workstation.

Steps Before Solar Panel Installation

Before starting the solar panel installation process, find out where to purchase the panels and review the company’s reputation.

The best place to get solar panels is from solar energy companies, though they are also available in online stores.

Solar panel systems mounted on frame with the sky on the background.

(Image: Mrganso12)

Before buying the panels, you must know how many solar panels you need. The panels are expensive, so you don’t want to buy too few or too many.

Second, you need to know where to install the solar panels. Generally, people install these panels on building tops, rooftops, and stand-alone facilities.1

The goal is to place the solar panel at a location most exposed to the sun (usually on the southern facing slope). It’s essential to know how solar works to plan your installation effectively.2

Third, the party should calculate the cost of setting up the size and type of system before installation. It’s important to note that most state governments provide subsidies to encourage using renewable energy and solar panel installation.

Fourth, you should create a checklist of the equipment needed for installation, such as

  • Charge controller (MPPT vs PWM)
  • Power inverter
  • Solar panels
  • Battery

Lastly, verify the solar system size you need. In this case, the person should calculate the wattage required by all electrical appliances they plan to use and how many hours per day each device will be used.3

These are the steps to take before the installation process. Following the steps above will help you understand the following:

  • Wattage requirement
  • Size of the solar battery needed
  • Wire size

Solar Panel Installation Step-By-Step Process

Solar panels can generate electricity for both home and commercial use.

It’s recommended to install the Photovoltaic panel on the rooftop for maximum possible sunlight hence getting maximum electricity from the device.

Three men working on solar panel installation on a building next to a road.

(Image: Los Muertos Crew13)

How to wire solar panels to the breaker box in parallel vs. series only differs when connecting the positive and negative terminals in the panels.

The following is the solar panel installation step-by-step process:

Step 1: Mounting Installation

First, one should fix the mount they will use to support the solar panels. Depending on the requirements, you can use either flush or roof-ground mounts. The durability and support of the whole system come from this base structure.

This is the best way to fulfill the process of how to install solar panels on roof. The installer should consider which direction to install the PV panels (polycrystalline or monocrystalline).

For the US and other countries in the Northern Hemisphere, experts recommend solar panel mounting installations to face south to get maximum sunlight.4

Moreover, the installer should slightly tilt the mounting structure. The tilt angle should be between 18 and 36 degrees.

Many solar panel technicians use solar trackers to amplify conversion efficiency.

Step 2: Installing the Solar Panels

The next step is to install the solar panels to the mounting structure.

Worker carefully installs solar panels on a roof.

(Image: Raze Solar14)

The process involves tightening nuts and bolts, and the installer is advised to ensure the whole structure is adequately secured to make it sturdy and last long.

Step 3: Electrical Wiring

Remember to adhere to all the safety tips before you start wiring. Electrical wiring should involve universal connectors such as MC4s because they can connect to all solar panels.5

However, before the electrical wiring process, the installer should know how to wire solar panels to breaker box in parallel vs. series.

  • Parallel connection: Connect negative (-) to negative (-) and positive (+) to positive (+). Each panel’s voltage will remain the same.
  • Series connection: One PV module’s negative (-) wire connects to another module’s positive (+) wire. This wiring amplifies the voltage to match with the battery bank.

Step 4: Connecting the System to the Solar Inverter

This straightforward process involves connecting the positive wire from the solar panel to the positive terminal of the inverter and the negative solar panel wire to the negative terminal of the inverter.

After connecting the system to the solar inverter, the installer connects the solar inverter to the solar battery and grid input to produce electricity.

Step 5: Connecting the Solar Inverter to the Solar Battery and the Grid

An off-grid solar system should have a battery to store backup electricity. The installer should follow the same process by connecting the positive terminal of the inverter to the battery’s positive terminal and negative to negative.

After connecting the inverter to the battery, the next step is to connect it to the grid. The installer will use a standard plug to connect to the main power switchboard in this case.

Then connect an output wire to the electric board, which supplies electricity to the house or commercial property.

Step 6: Starting the Solar Inverter

After installing all the electrical wiring and connections, the last step is to start the solar inverter by switching on the house’s main switch.

Most electrical manufacturers make solar inverters with a digital display of the statistics regarding the usage and generation of the solar unit.

How To Wire Solar Panels to Breaker Box Parallel vs. Series

Solar technicians wire Photovoltaic (PV) solar panels in three basic but diverse ways.6 Each wiring method is used for a specific purpose.

Graphics of solar panel connection to breaker box showing solar array, solar charge controller, battery, inverter, breaker box, electric grid, and home are connected by positive and negative wiring cables.

For example, one wiring method can be used to produce more current, and another one can be used to create more output voltage. Some installers want the unit to power their home,7 while others may want to use the solar panel for AC unit or other functions.

Therefore, how to wire solar panels to breaker box in parallel vs. series depends on the amount of energy the user needs and how they spend this energy.

Technicians can wire solar panels together in series to increase voltage output, in parallel to increase output amperage, or in a combination of both parallel and series to increase both voltage and amperage output.8

How To Wire Solar Panels: Wiring Diagram for Solar Panels

The wiring diagram for solar panels illustrates how the connections work.

The solar panel is connected to the inverter, which is connected to the battery and grid.

Wiring diagram for solar panels graphics showing solar panel connected to an inverter, meter, and home.

(Image: Brgfx15)

The grid is connected to the main power switchboard, which supplies electricity to the house. Installers must understand the basic principles of connecting multiple solar panels to increase power.

Each wiring method works differently; therefore, having this knowledge will help someone improve the efficiency of their solar system.

How To Wire Solar Panels in Series

Series wiring amplifies the total system output voltage. This type of wiring is generally used when a grid connects to a charge controller or inverter that needs 24 volts or more.

Series wiring involves connecting the negative terminal to the positive terminal of each panel until the installer is left with a single negative and positive connection. Solar panels connected through series wiring sum or add up each panel’s voltages, providing total output voltage.

There are three ways of connecting solar panels in series wiring they include: Series wiring of Solar panels of the same characteristics: This method connects solar panels with the same power rating and the same characteristics.

To get the total voltage output, you will need to add up the voltage output of each panel.9 For example, if a person installs three 6 volts 3 amp panels, and the PV panels are connected in series, the array produces a total output voltage of 18 volts (6 + 6 + 6) at 3 amps.

Therefore, the system will produce 54 Watts (Amps x Volts) at full sun. Series wiring of solar panels of different voltages: In some cases, the panels may have different power ratings but similar current ratings.

For example, connecting three panels of 5V, 7V, and 9V at 3 amps will produce a total voltage output of 21 volts (9 + 5 + 7) and 63 watts of electricity. Series wiring of solar panels of different voltages and currents: In a case where the solar panels have different types of power ratings, to obtain total power, you will add up individual panel voltage together, the same as before.

However, this time, the amperage value is limited to the panel with the lowest value in the series.

For example, if there are three panels with 3V 1A, 7V 3A, and 9V 5A, then the array will give out a total of 19 volts at 1 Amp only.

Therefore, the energy derived from this setup will be 19 watts out of the possible 69 watts. Evidently, this reduces the array’s efficiency.

The 9V 5A array only uses 20% of its current potential, which reduces the panel’s efficiency, making it a waste of money to purchase this panel. As such, this method should be used provisionally, as the current output of the whole system is determined by the solar panel with the least rated current.

Additionally, series wiring is best done in unshaded conditions such as rooftops. If a single panel of the array is under a shade, it will bring down the power output of the whole array.

Each panel in a series wiring is crucial.

How To Wire Solar Panels in Parallel

Solar technicians use parallel wiring to boost the total system current. This wiring is the reverse of series wiring, as the solar panels are connected with all negative terminals together and all the positive terminals together.10

The connection goes from positive to positive and from negative to negative until you have one negative and one positive terminal to attach to the battery and regulator. In parallel wiring, the total voltage of all the solar panels connected remains the same as that of a single panel.

However, the output current is the total output of each panel. There are three ways to connect parallel wiring, they include:

Parallel wiring of solar panels of the same characteristics: When all panels have the same power rating, the output voltage remains the same. For example, three solar panels with 6V 3A power rating connected through parallel wiring will have the same voltage value of 6 volts.

On the other hand, the total amperage increases to 9.0 amperes (3 + 3 + 3), producing a total of 54 watts at full sun. The current adds up as long as the output voltage remains constant and panel voltages are the same.

Parallel wiring of solar panels with different currents and voltages: For example, if three panels are connected with power rates of 3V 1A, 7V 3A, and 9V 5A, the current will add up same as before, but the voltage decreases to the lowest value which is 3V in this case.

The panels must have the same output voltage for maximum efficiency in parallel wiring. In a case where one panel has a higher voltage, it will give load current to the state where its output voltage reduces to that of the lowest voltage panel.

How to wire solar panels in parallel really depends on the voltage. In the case above, the panel with a power of 9V 5A will function at a maximum of 3V.

The low voltage panel influences the other panel’s functionality, and this reduces its efficiency. As a result, money will be wasted when purchasing this high-power panel.

Experts and technicians alike do not recommend parallel wiring of solar panels with different voltage ratings as the lowest rated voltage panel determines the total voltage output of the whole system. Therefore, connecting panels with the same nominal voltage value in parallel wiring is important.

Even so, the panels don’t necessarily need equal ampere value. Parallel wiring means each panel operates independently; therefore, this method is more suitable for mixed-light conditions.

If shade covers any panels, the remaining ones will still generate power as expected.

How To Wire Solar Panels to Breaker Box

Several delicate connections are involved in the process of how to wire solar panels to breaker box in parallel vs. series. The installer should take the following steps:

Step 1: Set up the solar panels, then remove fuses from the junction boxes, controller, and inverter. Here the installer should disconnect the breaker box from the grid.

Step 2: Use draw cables and connect the inverter to the main breaker box.

Step 3: Connect the solar charge controller to the solar panels. It would be best if you did not turn it on the system to test it out at this step; instead, use a multimeter to verify that the panels can supply enough current.

Step 4: Connect the controller to the batteries. At this point, the installer has a lot of wires, and they should use the bus bar junction if needed.

Step 5: Connect terminals to the inverter from the battery and controller.

Step 6: Ground the remaining open wires and add the fuses back to their respective slots.

Step 7: Switch on the controller and use a multimeter to verify the current and voltage throughout the circuit.

How To Wire Solar Panels to Breaker Box in Parallel vs. Series: Precautions (Solar Panel Installation)

Solar panel installation come with their fair share of risks.

There are several solar installation hazards that you should look out for.11

Experts recommend taking the following precautions when learning how to wire solar panels to breaker box in parallel vs. series:

  1. The installer should always use insulating gloves when connecting cables to terminals or dealing with open wires.
  2. Work with a fire extinguisher to decrease the risk of a fire outbreak. Installers are cautioned not to use water as it may spread the fire further.
  3. Use a set of pliers to connect the battery terminals and maintain the required distance.
  4. Installers should not mangle the wires by screwing them in too tight.
  5. Do not leave open cables without covering the open end with electrical tape.

How To Wire 12V Solar Panels to 24V

Most off-grid solar panels have 12-volt charging systems.

Any installer with a 24V battery system should not worry because it’s not difficult to know how to wire 12V solar panels to 24V battery. All they have to do is wire two 12V panels in series.

To wire these two panels in series, the technician should:

Step 1: Connect the negative terminal of the first solar panel to the positive terminal of the second solar panel. All junction boxes have embossed + and – symbols, usually close to the cables at the back of solar panels.

Step 2: Grab the remaining positive terminal from the first panel and the negative terminal from the second panel and connect them to the input of the solar regulator in their corresponding terminals.

Step 3: The solar regulator will detect the solar panels and begin charging the battery.

24 Volt Solar Panel Wiring Diagram

Anyone with a 24V battery should get a single solar panel with a high enough voltage to charge it.

The panel should have a high enough capacity to charge the panel even in the winter.

Home hybrid solar plant graphics showing the solar panel wiring diagram including solar panel, solar panel counter, electrical network, solar panel controller, AC/DC converter, battery for solar power consumption.

(Image: Macrovector16)

Therefore, the installer should get a 30-45 voltage panel. To summarize, connecting solar panels and forming bigger arrays is easy.

Choosing which method is most suitable for you depends on what amount of current and voltage you are aiming for. Parallel wiring produces more amperes, while series wiring produces more voltage.

Before you get started on your own project, make sure that you understand how to wire solar panels to breaker box correctly, and always consult a professional if you’re unsure about any of the steps involved.

Frequently Asked Questions About How To Wire Solar Panels

How Long To Install Solar Panels?

Solar panel installation takes 1-5 days if you do it by yourself, but a team of experts can finish it in 1-3 days.

What Type of Wire Is Used for Solar Panels?

Most solar panel installations use aluminum and copper wires.

What Are the Steps on How To Connect Solar Panel to Water Pump?

You can connect solar panels directly to a water pump, but the best way is to connect the pump to the solar battery.

What Is Needed To Install Solar Panels?

You will need a solar inverter, solar panel, battery, and regulator to install solar panels.

What Are the Steps on How To Wire Solar Panels to Breaker Box In Parallel vs. Series and How To Test a Solar Panel?

How to test a solar panel? Testing solar panels involves using a multimeter by connecting the positive terminals of both the panel and the multimeter and doing the same for the negative terminals. Then read the multimeter to determine the voltage output.

How Much Do Solar Panels Cost?

H ow much do solar panels cost? Solar panel costs range from $16,870 to $23,170.

Charging Tesla With Solar Panels, Is This Possible?

Charging Tesla with solar panels? Yes, you can charge a tesla with solar panels, provided there is enough power.


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