Wiring solar panels may sound intimidating, but you can configure the panels once you understand the basics of different stringing methods. You’ll see how it affects the voltage and current, and pair them with the perfect inverter to have your system up and to function quickly.
Understanding the role of voltage and how it works in unison with your inverter’s capacity helps you know how too much or too little voltage can impair your inverter’s output.
Wiring or stringing your solar panels with the proper inverter produces an efficient power source and prolongs the life of your equipment.
The inverter requires the recommended ‘starting voltage’ to kickstart the system for an efficient installation. Modern software tailor-made to work with solar systems can help you understand if your string lengths are appropriate or help you design a plan just for your circumstances.
When you face your panels in too much shade, understanding how lack of sunlight impacts your daily voltage production is a crucial element that helps you form an installation plan.
In this article, I’ll talk about the following topics:
- Voltage vs. Current
- Connecting Solar Panels
- Series vs. Parallel Methods
- Best Type of Wire
- How to String Solar Power
Wiring solar panels for efficiency is complex, but following the steps in this article is a good starting point. This introduces the basic terminology and dips into the topic’ is it Better to Wire Solar Panels in Series or Parallel?’
How Should I Wire My Solar Panels?
Before we start wiring anything, we need to understand electrical lingo and state regulations governing the solar industry. It’s so important to string our solar panels correctly. (Firecode pg. 12 & Electrical code pg. 14)
- Voltage
- Power
- Current
These terms are not interchangeable, but each plays an essential role in solar panel wiring. Think of it this way; they are dependent on each other. You can’t have one without the other.
Are Voltage and Current The Same as Power
If you understand the basics, skip ahead to the next segment. If you need a refresher or just starting to grasp the basics, follow these simplified explanations to help you understand the terminology used for wiring solar panels to electricity.
See also: How to install solar panels (Detailed Step-By-Step Guide)
Voltage
‘V’ is the abbreviation of Voltage and the juice that makes electric charges move through wires or other source conductors. This voltage juice isn’t technically a force but creates movement, called a current; voltage creates a current.
Another way is to say that voltage is the charge between two points responsible for creating the electricity to flow. Voltage is potential energy. In solar energy, voltage is influenced by sunlight, called irradiance. The more irradiance a panel captures, the higher the voltage.
Surprisingly, the voltage may be higher on the solar array scale on a cold sunny day. In contrast, the opposite happens on hot days, which reduces the voltage. Simply put, temperature influences the amount of energy a panel produces.
Understanding this push and pull action explains the intricacy of a solar panel wiring diagram and connecting solar panels to a home’s electrical circuit for optimum results.
Current
A current is the rate of a flowing charge of positive or negative particles (electrons). This movement produces heat, a magnetic field, or a chemical transformation. In electrical terms, this current is measured in amps (amperes). The letter ‘I’ represents the current in equations.
Power
The letter ‘P’ symbolizes power, the rate of transferred energy. Voltage times current equals power (V*I=P). We now have measurable watts (W).
Why is this important? In solar PV systems, the inverter not only converts DC power from solar (array) to AC power to power our homes or campers (etc.). On the grid, it optimizes power output by manipulating the current and voltage.
To understand how to utilize its full potential in wiring solar panels in series and where the solar panel should be operated from, read this resource on power voltage curves.
Now that we got those terms out of the way, let’s jump right in and address how you can connect three solar panels in series and which is safer: series or parallel?
How to Connect Solar Panels in Series or Parallel
Understanding solar panel installation takes some long-winded technical explanations. The gist of all that jargon is that a solar PV system that works also meets your needs.
Step one, you need to wire the panels in such a method as to design an electrical circuit. This step maximizes current flow and binds it to the inverter to transform DC power (captured by your solar panels) into a usable AC power source and send the excess back to the grid.
This process of stringing for efficiency is what installing solar panels is about and allows us to become energy efficient, non-reliant, and greener—a better choice for the environment.
For clarity, because undoubtedly, other terms will introduce themselves, we’re discussing stringer inverters, not microinverters. String inverters are built to a specific voltage range for operating functionality.
What defines Series vs. Parallel Stringing Methods
The main difference is how each method affects the electrical current and voltage on the circuit. The charts below demonstrate how you can connect three solar panels in series and which is safer: series or parallel?
It’s not a trick question. They’re both safe if they’re wired properly with the correct components.
Stringing in a Series:
Picture nine panels (⌧) on the roof like this:
⌧–⌧–⌧
[ connects to the panel above and below
⌧–⌧–⌧
] connects to the panel above and below
⌧–⌧–⌧
|
This drawing is a simplified single-string panel setup. Energy loops from one panel through a ribbon pattern from one to the next in a line. (See illustration above, X represents individual panel)
Solar panels, like batteries, have positive and negative (cathode and anode) terminals. In a series configuration, the positive terminal on panel A connects to the negative terminal in panel B until all panels are connected (in a series).
The result of stringing in services is that each panel contributes to the total voltage accumulated on the string, but the current always stays the same. Therefore a hundred panels add the voltage of a hundred, but the current produced remains the same whether ten panels or a hundred.
If even one panel is situated in the shade, it can affect the amount of current created in the entire string. So if shaded panel A produces X amount of current, the whole collection of panels on that string will default to the lowest amount or X of currently produced.
Stringing in series becomes a disadvantage because of that flaw in the system, and one bad apple spoils the batch.
Stringing in a Parallel Sequence:
Look at this simplified version for wiring solar panels in a parallel diagram.
⇮
⏠
⌧–⌧–⌧
| | |
⌧–⌧–⌧
| | |
⌧–⌧–⌧
⏡
|
At a glance, stringing solar in a parallel pattern is more complex and requires more wiring.
The installation process of stringing parallel means connecting all the negative terminals with negative terminals to the next panel, which means all positive terminals are connected to positives using one wire to perform this function.
The result, however, produces more current (amps) on the circuit, and the current-voltage remains equal to each panel’s voltage.
This translates into more efficient power because the shaded panel doesn’t negatively impact the other panels, and the current created by this stringing pattern isn’t diminished.
Parallel stringing is perhaps a better option. One bad apple still makes applesauce.
12V vs. 24V
Understanding the important differences between parallel and series stringing, you’re still wondering how I can wire a 24V solar system.
Upgrading from 12VDC to 24VDC is only doable in 24V inverter systems. And as we described in series or parallel systems, the extra power in a series string can’t be extrapolated or stored with any kind of efficiency in loading the battery.
The parallel stringing has more amperage capacity. Since standard solar panels and matching, batteries come in 2/24/36V (and up), parallel stringing nearly doubles output time per battery, and parallel recharges batteries quicker.
Therefore, Can You Wire 12v Solar Panels to 24v?
Yes, you can wire a collection of solar panels and associated batteries in parallel or series configurations for 12V, 24V, and higher DC systems.
And What Type of Wire Is Used for Solar Panels?
Electrical wire, plain and simple. You can choose single and multiple-strand wire cores. It’s only logical that a multi-strand wire or conductor has more uses and outperforms a single strand. Single strand works well for home electrical wiring and solar, though not ideal for high wind.
For optimum conducting, use multi-strand wire but don’t let anyone sell on the theory that you need special cables for solar panels.
Thicker wire is a better investment, saving you from upgrading later. If you need to calculate wire length against amperage, use this equation:
The output of 7 amps derived from 15.10 ft (4.6 m) length of wire (+35% margin) 7 + (35% of 7) equals 9.45 amps or 10 amp wire.
Can I Use Speaker Wire for Solar Panels? You can, but the casing on speaker wires may not tolerate the heat on the roof. Speaker wires are meant for speakers and are used on the interior.
Deciding Factors for Stringing Solar Panels
It’s impossible to string your solar network without understanding inverters and solar panels. The maximum allowable voltage is 600V for most residential solar panel installments in the USA.
Information You Need When Determining How to String Solar Panels
There are several essential pieces of information about your inverter and solar panels that you need before determining how to string your solar array.
Inverter Details available from your manufacturer (see data sheets):
- Minimum voltage (start voltage) or V input, min is the necessary voltage for an inverter to function
- Maximum DC input (input voltage) or V input, max is the amount of voltage the inverter can absorb
- Maximum input current specifies the amount of energy the inverter is capable of holding
- Inverter MPPTs (Maximum Power Point Trackers) are included (DC to DC conversion)
Inverters maximize power regardless of climate. This technology maximizes power by defining the current and voltage looping through the system. Optimizing panels for maximum exposure is vital, and consistent exposure increases efficiency.
As noted above, the function of inverters is to maximize power output as the environmental conditions on the panels vary. A design feature in the panels allows them to do this through Maximum Power Point Trackers (MPPTs), which identity the current and voltage at which power is maximized.
Multiple MPPTs navigate fluctuations in conditions and work best if connected to adjusted MPPT inverters to balance energy production.
Solar Panel Types:
To choose the best panels to work with your inverter, check the specks on your panel.
- The maximum voltage the panel can convert into no-load; open-circuit voltage (VOC)
- Short circuit current (ISC) is the current in the cell when the voltage is zero.
Because performance (inverter and panels) is measured on Standard Test Conditions (lab setting), individual and actual current and voltage of planes may fluctuate.
Your performance values need to be adjusted based on your local and seasonal temperatures and the location and exposure of your panels so that your string distances match the PV system.
Wiring Solar Panels FAQs
Wiring solar panels just open a whole set of how-to-questions. Some may want to wire an entire house or farm; others just want to venture off-road and carry power in their RVs to remote locations.
How Do You Wire A 12-Volt Solar System?
Can I Use AC Cable For Solar Panels?
A DC cable is made from finer copper strands and determines that you’re not using the best product when you use an AC connection cable. Whichever cable you choose should meet your state’s electrical and fire code regulations.
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