Solar panels in homes and offices are the most sustainable energy options out there. They use one of nature’s most potent and abundant resources – sunlight to harness electricity. Solar panels have cells with photovoltaic systems (PV systems) that use semiconductor technology to convert sunlight directly into electricity.

The demand for solar energy is steadily increasing, with over 970,000 UK homes using solar panel systems. One of the best features of a solar power system is the flexibility of expanding power capacity. You need not install the entire large setup but keep adding as per budget requirements. Solar power prices have also been on a steady decline and are estimated to likely be cheaper than gas or fossil fuels by 2030.

Even with the best-possible components available in the market, there is no guarantee for the system to function as promised. That is due to the connection type, not just because of the PV panels.

It is quite frequent that many people miss out on planning the best type of connection for their solar panels. An important decision in the whole process, solar connections can enhance or slow down the panel’s performance and other components. If you are one of the many homeowners that have joined the solar energy revolution, we want to make it as easy as possible for you to expand your solar capabilities. This simple guide aims to make you understand wiring solar panels together and why certain connections are ideal based on your requirement.

Basics of Solar Panel Wiring

Wirings play an essential role in a functional solar panel system. This process is also known as Stringing. Every series of panels connected are called a single string.

Before we dive into different types of wiring, let us look at the essential elements of the connection setup.

Wiring Solar PanelsSolar wiring is the process of using wires to link all of the panels in a solar array to form a circuit through which electricity travels. The line is connected to an inverter, which converts DC into usable AC power for homes and sends it to the grid.

Wires and cables used in solar wiring uses are not your regular ones. They are resistant to heat, moisture, water, and UV with different insulations based on the placement of panels. Although used interchangeably, wires are different from cables. A solar wire is a single conductor, while solar cables are a composite of several conductors or wires held together by an outer jacket and are more heavy-duty.

Different wiring configurations need knowledge of how they affect the performance of solar arrays’ voltage, current, and power. To make the best of your solar panels, stringing can be done in two options.

Solar panel connection: series vs. parallel wirings

You have three ways of connecting solar panels to create a functional power set up to provide solar electricity to obtain the desired power for your house.

  1. Series connection
  2. Parallel Connections
  3. Combination of both series and parallel

Connecting Solar Panels in Series

Series panels involve the travel of current in a single direction along the circuit. This makes all the current in the circuit to flow across all of the connected loads. A series circuit is continuous and has a closed loop. That means when you break the circuit at any given point, the entire series stops functioning. A classic example would be a steam iron or old models of string lights – where the entire set would be affected when one snapped. You would need to locate the defective bulb and replace it to get the lights working.

Picture a regular battery – it has a negative and positive terminal. The same is the case with solar panels. The wire from the positive terminal of one solar panel is connected to the negative terminal of the one next in line, and so on to create a series connection.

Increased Voltage, Same Current

You add the voltages together in a series panel, but the amperage (current) does not increase. That means each panel additionally adds to the overall voltage of the string, while the total current is the same. The benefit of the series is that it is easy to transfer over long distances.

Solar Panel InstallationWhen wiring solar panels in a series, the voltage is additive, but the current remains the same. For example, if you installed 5 solar panels in a series and each was rated at 14 volts and 5 amps, the entire array would be 70 volts and 5 amps.

A principle to note is that lower voltages refer to higher currents, and higher voltages mean lower currents. This is key for panels especially aligned in a series connection as this configuration shoots up the voltage every time you install an additional panel. And hence the total current across the system is lower.

This setup increases savings with smaller wires and shorter cables alongside making the solar panel system more efficient, reducing electrical losses.

Disadvantages

A recurring downside to series solar connections is the problem of shading. When panels are strung in series, they are inter-dependent as the current flows from one string to the other. In the event of shading, even on one panel, the whole string gets affected and reduces in power load.

Series connections also carry reliability issues as all strings are connected with one main wire. Should the same fail, the entire system shuts down instantly.

Overcoming Disadvantages of Series Connection

While you cannot solve the issue of reliability, using a micro-inverter for every individual panel provides the best solution to shading, as every panel will be independent of the other one for its power support. In this way, the shading of one panel will not affect the overall power output of the whole solar system.

When should you install a series connection?

  • It is a general presumption that series connection is the best choice for higher voltages.
  • It is also a wise choice when the inverter and solar panels are placed far apart. This allows the system’s voltage to adjust and increase to equal itself to the inverter’s voltage input.

Connecting Solar Panels in Parallel

Parallel connections in solar panels imply separately wiring all the positive and negative terminals. The dual connections are then linked to the inverter of the solar panel system to generate power.

In parallel connection, the positive terminal from one solar panel is connected to the positive terminal of another panel, and the same is done with the negative terminals. The positive wires are matched to a positive connector within a combiner box, and the negative wires are connected to the negative counterpart. A PV Output Circuit is formed when several panels are wired parallelly.

Increased Current, Same Voltage

Unlike a series system where voltage increases, it remains the same in parallel wiring. You add the amperages together and keep the voltage the same across arrays.

Solar Panel InstallerBecause of the separate connections of positive and negative terminals, parallel strings reduce the overall effect of shading on solar panels. Even when one panel is heavily shaded, the remaining panels are not affected and can operate normally. The system does not shut down as the current flow of the rest of the string is not reduced.

Wiring solar panels in parallel gives you the flexibility to have an extra set of solar panels in your system to produce more energy. As the voltage is kept low, you can quickly meet the voltage limits of the existing solar power inverter without getting a new one to match increased production.

Disadvantages

Running an electrical circuit with high amperage requires thick cables to carry the load across. Imagine the thickness of a water pipe that gushes a large volume of water through the system. Parallel connections also require wires and cables that support heavy-duty current flow.

That apart, they are also more complicated and expensive to install.

When should you install a parallel connection?

It is usually advised to set up a parallel connection when the system area is relatively smaller and caters to low supply loads or has a battery with a low voltage requirement.

Combination of series-parallel connections

Now that there is enough said about both series and parallel connections in a panel let us look at the result when both setups are included in one array.

Establishing the connection according to the voltage and the current input range of an inverter or a charge regulator is often necessary.

There may be instances you don’t get close to getting the ample voltage and current range by solely configuring a series or parallel connection. A series connection could exceed the voltage limit. While with a parallel connection, you can increase the current limit while limiting the supply of high active power through the configuration.

When you include both solar panels in a dual fashion of series and parallel, the voltage in each string combines while the current (or amps) remains the same.

Then, the voltage in the two strings stays the same while the amps are added together. This method of combining both types gives the advantage of a series connection, i.e., reduced electrical losses with reduced costs along with the reliability of a parallel connection.

Summary

You must have a good idea about the differences between serial and parallel connections. You need to pick an ideal system based on your specific use and roof area.

A parallel connection is probably the most efficient for solar panels of different capacities. If your system is at a distance of more than 20 feet, then a series connection is feasible. Whether solar arrays are to be connected in series, parallel, or combination – the decision depends on your specific expectations from the solar panel system. These different wiring configurations affect the voltage and current in the panel circuit.