Solar Module vs Solar Panel
Solar modules and solar panels refer to essentially the same component of a photovoltaic system – the unit that converts sunlight into electricity. The term “solar module” is the precise, industry-standard name for a single PV unit, as used in certifications, standards, and technical literature. The term “solar panel”, meanwhile, is entrenched in popular usage and marketing to mean the same thing, albeit without the strict definition. Historically, panels could imply a grouping of modules, but in today’s solar industry that distinction has largely vanished.
Both modules and panels share identical structure and function when referring to PV devices – there is no performance difference between a product called a panel and one called a module.
The main difference lies in terminology and context. For clear communication: use the term module for formal and technical discussions, and feel free to use panels when simplicity or familiarity is more important. Understanding this nuance not only helps in speaking the language of solar professionals but also in interpreting documentation and standards correctly. In the end, whether you call it a solar module or a solar panel, you’re talking about the same marvel of engineering that harvests the sun’s energy and moves us toward a more sustainable future.
These words are frequently used interchangeably, even by professionals, but is there a real difference? This authoritative guide will define both terms clearly, explain how they overlap, and highlight any structural or functional distinctions. We’ll also draw on industry standards, manufacturers’ insights, and scientific perspectives to clarify usage.
What is a Solar Module?
A solar module – often called a photovoltaic (PV) module – is the fundamental building block of a solar power system. Technically, it refers to a single, encapsulated unit containing multiple solar cells wired together. According to the National Electrical Code (NEC), a PV module is defined as “a complete, environmentally protected unit consisting of solar cells, optics, and other components, exclusive of tracker, designed to generate direct current (DC) power when exposed to sunlight.”
In practical terms, a module is the familiar rectangular unit you see in solar installations, composed of silicon cells (or other semiconductor materials) protected by glass on the front and a backing material, all held together in an aluminum frame. The cells inside a module convert sunlight into DC electricity, which can then be combined with other modules’ output and converted to AC by an inverter for use in homes or the grid.
Modules come with standardised ratings and specifications. For instance, each module has a rated power output (in watts) under standard test conditions, along with parameters like voltage and current at maximum power, open-circuit voltage, short-circuit current, efficiency, and physical dimensions.
Manufacturers and certification bodies universally use the term module in technical documents and standards. International organisations such as the IEC (International Electrotechnical Commission) and UL (Underwriters Laboratories) exclusively refer to these products as PV modules in their certifications (e.g. IEC 61215 for performance, UL 61730 for safety).
If you read any solar panel datasheet or installation manual, you will almost always see the word module used in the specifications and warranty information, underscoring that this is the precise technical term.
Structurally, a solar module is a single, self-contained unit. It typically consists of:
Solar cells – individual photovoltaic cells (often made of crystalline silicon) that generate electricity from sunlight.
Encapsulation – layers of protective material (like EVA polymer) that laminate the cells, shielding them from moisture and mechanical stress.
Front glass – a high-transparency, tempered glass layer that protects cells from the environment while allowing sunlight through.
Backsheet – a protective rear layer (or a second glass layer in bifacial modules) providing insulation and protection.
Frame – usually anodised aluminium, giving the module structural rigidity and enabling mounting.
Junction box – attached at the back, housing electrical terminals and bypass diodes, and providing connections (often MC4 connectors) to link modules in a system.
All these components are engineered into one unit – the module – which is designed to be weatherproof and durable, often with warranties of 20-25 years or more on power output.
What is a Solar Panel?
The term solar panel is commonly used to refer to the exact same device as a solar module – especially in everyday language. In most modern contexts, a “solar panel” means a single PV module unit. If a homeowner says “I have 20 solar panels on my roof,” they almost certainly mean 20 modules. In the solar industry’s marketing and casual conversation, panel has become the go-to term for the product that installers mount and wire up.
Even many manufacturers use “panel” on their websites or brochures because it’s the term most people recognise. However, technically speaking, the word panel has a slightly broader or different meaning in certain contexts. Some authoritative sources define a photovoltaic panel as an assembly of one or more modules that are pre-wired together and field-installable as a single unit.
In other words, a panel could be a larger unit that contains multiple modules. For example, historically one might have called a series of modules bolted together (and wired in factory before installation) a “panel.” An older definition put forth by some experts is that a module is the actual individual unit (often colloquially called a panel), a panel is a group of modules assembled together, and an array is a group of panels.
By this definition, if you took three modules and fixed them into a frame as one assembly, you could call that assembly a single panel (composed of three modules), and a collection of such panels would form an array. In practice today, this nuanced distinction has largely faded. The vast majority of solar equipment sold consists of individual modules that are installed one by one, and people call each of those units a “panel.” The distinction where a panel meant a set of modules is now rarely observed in the field.
Standards organizations and electrical codes do not even use the term “solar panel” in official definitions – they stick to module (and array) for precision. As a result, in most technical writing and conversations among professionals, panel and module refer to the same thing: one self-contained PV unit.
It is worth noting that the word panel can also refer to solar thermal panels (solar collectors for hot water or air heating). This is a completely different technology – using sunlight to produce heat rather than electricity. In common parlance, people might say “solar panels” to mean photovoltaic panels on one occasion and solar hot water panels on another. Because of this, some scientists suggest that the term “solar panel” by itself is not very precise, since it could mean either a PV module or a solar thermal collector.
In academic and industry discussions, one might clarify by saying “solar PV panel” (meaning a photovoltaic module/panel) versus “solar thermal panel” to distinguish the two. In this article, however, we are focusing on photovoltaic devices; whenever we say solar panel, assume it refers to a PV module unless stated otherwise.
Modules and Panels: Similarities and Overlaps
In the context of photovoltaic power systems, solar modules and solar panels are, functionally, one and the same. Both terms describe a unit that generates DC electricity from sunlight via the photovoltaic effect. There is no difference in how a device labelled a “module” or a “panel” would perform – if they are referring to the same physical product.
For example, a 400-watt solar panel from a manufacturer will have identical electrical characteristics and construction as a 400-watt solar module from that same manufacturer; the difference is purely in naming convention.
Because of widespread interchangeable use, many industry professionals use the terms loosely when speaking. An installer might say “We’ll mount the panels on your roof” while the technical permit drawings label them as “PV modules.” This overlap in terminology is acknowledged by experts: the terms are often used interchangeably, with any distinction being mostly semantic or based on habit.
Using "solar panel" in casual or marketing communications is completely acceptable, and virtually everyone will understand it means a PV module. Even some manufacturers who know the technical nuance will talk about their “solar panels” on e-commerce sites or advertisements because that’s what customers search for and understand. In fact, “solar panel” is by far the more common search term on the internet.
From a technical accuracy standpoint, “module” remains the correct term when precision is needed. Industry standards, product certifications, and engineering documents stick to solar module. The NEC (National Electrical Code) also uses module for single units and uses terms like array for a group of modules; it does not define a term “solar panel” at all.
Therefore, while calling a module a “panel” is not wrong in conversational terms, professionals are careful to use the word module in contexts where clarity and conformity to standards matter. Doing so helps avoid any confusion – for example, a panelboard in electrical jargon is something completely different (an AC electrical distribution panel), so using module for the DC-generating unit prevents mix-ups in technical discussions.
When the terms diverge: In rare cases, the word panel might be used for a higher-level assembly. For example, some off-grid or portable systems have foldable solar panel kits which actually contain two or three smaller modules hinged together – here one might literally say the panel has multiple modules. Likewise, the term AC module (or AC panel) is used for a PV module that has a microinverter attached, producing AC output; but even in that term, the word module is used by standards because each unit is still fundamentally a module with added components.
Generally, unless you have a specialised use-case, you can assume each solar panel you buy or see is one module.
Structural and Functional Considerations
Given that a solar panel in the PV sense is essentially the same physical object as a solar module, there are no intrinsic structural or functional differences between the two when referring to photovoltaic equipment. Both consist of the layered construction described earlier (cells, encapsulant, glass, frame, etc.) and both produce DC electricity under sunlight. Any two modules/panels of similar type (say two 300 W crystalline silicon units) will work in the same way and can be used interchangeably in an array, regardless of whether someone calls them panels or modules.
One way to think of the relationship is hierarchically. A single solar cell is the basic unit that produces a small voltage. Cells are wired together to form a module, which is the smallest standalone unit that can be used on its own in a system. In some technical depictions, when you connect one or more modules together as one physical unit, you get a panel, and when you connect multiple panels (or modules) together electrically and mechanically, you create an array (the complete solar generator).
In modern usage, the term "solar panel" is often applied to what is technically a single module, whereas historically a panel could mean a group of modules assembled. An array is the full collection of modules/panels wired into a system.
In terms of function, both a single module and a single panel (if defined as one module) will have the same function: converting sunlight to DC power. If one uses the older definition where a panel can contain several modules, then the panel will simply have a higher power output (being equivalent to a small array of modules) but still the same function of generation. For example, three 100 W modules assembled as a panel would function as a 300 W generating unit. But again, this is not common practice in today’s industry – typically each panel you buy is one module rated at its own wattage, and you combine them in the field to make an array.
It’s important to clarify that outside the PV context, a solar thermal panel (for heating water or air) has a completely different structure and function – usually a metal absorber plate, pipes, insulation, and glazing, producing heat instead of electricity. Those are casually called solar panels too, which adds to the confusion. However, a solar module, by definition, refers only to PV devices, not thermal. Thus, using the term solar module implicitly means a photovoltaic panel. Using solar panel without context could mean either, though most often people mean the PV type. This is why in scientific writing, authors sometimes avoid the standalone term solar panel and use “PV module” or “solar PV panel” for clarity.
Industry and Standards Perspective on Terminology
From a standards perspective, precision in terminology is emphasised. The International Electrotechnical Commission (IEC) and other standards bodies uniformly use module. For instance, IEC standards for performance and safety of solar equipment (like IEC 61215 for module performance and IEC 61730 for module safety) all apply to PV modules. In these documents, you will not find the word "panel" used to describe the equipment under test.
Similarly, the Underwriters Laboratories (UL) standards and certification listings talk about modules. A solar manufacturer seeking certification will submit their product as a PV module to testing labs. The term PV panel might appear in non-technical contexts, but it isn’t a formally defined term in those standards.
Electrical codes, such as the US NEC or international equivalents, also stick to the term module. The NEC Article 690 (Solar Photovoltaic Systems) consistently refers to modules, arrays, and strings, but not panels. The reasoning is to maintain unambiguous language – panel in electrical terms often refers to something like an electrical service panel. By using module, the code avoids any possible confusion.
In the UK, standards and guidelines (like those from the Microgeneration Certification Scheme (MCS) or the IET’s Code of Practice for Solar PV) similarly use module in technical sections, although in customer-facing summaries the word panel may appear for familiarity.
Manufacturers tend to navigate the terminology based on audience. Technical documentation (spec sheets, installation guides, engineering drawings) will use module, aligning with the formal definitions. For example, a spec sheet will be titled “XYZ 400W Solar PV Module” and refer to the product as a module throughout. On the other hand, marketing materials and sales teams speak about solar panels, since that’s what resonates with consumers. A solar company’s website might say “Our panels have industry-leading efficiency,” while the spec sheet linked on the same page says “module efficiency: 20%”. This dual usage is widely accepted. One solar module manufacturer candidly notes that their products are officially classified as PV modules, but they understand that “‘solar panel’ is often more familiar to the people installing, selling, or buying them.”
Which Term Should You Use?
The choice of solar module vs solar panel often comes down to context and audience. If you are speaking with other engineers, writing a formal report, or dealing with permits and specifications, solar module is the accurate term and the one that will match the language of standards. Using the precise term in professional settings underscores technical credibility and avoids any chance of misinterpretation. For instance, a bill of materials for a project will list the number of modules, not panels, to be installed.
On the other hand, if you are explaining your solar installation to a neighbour or creating educational content for the general public, solar panel is perfectly fine and likely preferable. It’s the term most non-specialists recognise. In fact, insisting on “module” in casual conversation might confuse people who are not used to that word.
The key is understanding that there is no functional difference – so you won’t be lying or making a factual error by using either term in the right setting. As one industry source advises: Use “module” in technical and regulatory contexts, and use “panel” when talking to homeowners or laypersons. There is no need to correct someone who refers to their system’s modules as panels. What matters at the end of the day is that the solar equipment is correctly installed and generating power, not which word is used.
