Solar Panels Sizes and Wattages

Solar Panels Sizes and Wattages

Solar power panels harness the sun’s power in the form of light and the conversion of energy into electricity. Though the consumer may associate the solar panel with the residential rooftop assemblies, solar panels are available for a broad range of the applications such as electronic devices, individual gadgets, and car batteries.

Solar panels used generally come in a standard size that meets most homeowners as they fit on many roof sizes and generate enough energy to lower the electric bill monthly. A solar installer can assist you in finding the best solar panel. Size and power wattage are some of the factors considered while purchasing or installing solar panels. The following are factors such as the size and the wattage of solar panel described to give insight while installing the solar systems,

Size of the solar panel

Solar panels come in all kinds of shapes, sizes and weights. Solar panels don’t necessarily go up in size and weight with increasing wattage so, for instance, you can’t assume a smaller wattage panel will actually be smaller in physical size. Two panels of equal wattage may be quite different in physical size and weight. And, a solar panel can be a weighty bulky item.

Width and length

Though the width and length slightly vary, many organizations manufactures these systems in standard sizes. The size used for the residential connections is 65 inches by 39 inches. On the other hand, for the commercial uses is 77 inches by 39 inches.

The small size is a good fit for the residential projects in maximizing the available roof size. Many commercial projects have many solar panels, so the slightly large panels are more of an ideal choice. Sun is the exception of width and length. The residential panels are typically 61 inches by 41 inches and slightly wide and short compared to the standard solar panels.


The solar panels’ depth normally ranges between 1.4 inches to 1.8 inches though you can see that many manufacturers have increased their depth.


The residential solar panels typically weigh about 40 pounds. The business solar panels typically weigh close to 50 pounds. Notably, there is a structural analysis of computing whether a roof can withstand the solar panels’ additional weights. A solar panel’s weight can be crucial in cases where support is required without access to framing.

The solar cells numbers

The cells are the electrical devices that convert sunlight into power. To produce a significant amount of power, these cells are together connected in a solar panel. The 60 cell modules are the typical standard for home applications; however, slightly large commercial solar panels have about 72 cells.

Solar Panel Cells

The lead-in solar panel efficiency, which is Sunpower, uses about 96 cell panels. Solar installation firms usually look at cell numbers while determining the compatibility with microinverters.

Power wattage

Power wattage, also called power output, is a crucial factor to take into consideration while comparing solar panels’ options. You are likely to get your solar installer say it is a 255-Watt panel, or the recommended solar panel should be 300 Watts. While taking a note from a solar installer, you are likely to see numerals such as 300W, 245W, or 345W adjacent to the solar panel name. These refer to the solar panel’s capacity, wattage, and power output.

The systems are normally rated by the direct current power produced under the standard test conditions. The solar panel outputs are expressed in (W) units and represent the solar panel’s theoretic production of power under ideal temperature and sunlight conditions.

Several home solar panels on the marketplace presently have power output ratings that range from 250 to 400 watts, with high power ratings being preferable to the low power ratings. The total output of the solar panels has a crucial role in the general price of the solar panels.

STC and PTC Wattage

About the energy, size is denoted by DC watts under the PTC or STC conditions. The STC is the power wattage measured under the lab conditions. The PTC is what the solar panel manufacturer utilizes in the technical equipment specifications. Many standard panels have about 230 watts. The manufactures of efficiency equipment range between 327 to 345 watts. PTC of the solar system is usually 10-15% low compared to its STC. For the standard panels, the PTC ranges from 195- and 247-watts.


Solar power panels are notoriously inefficient. There are lots of technical reasons for that that can be found elsewhere if inquiring minds want to know. Officially, “efficiency” is called the “sunlight conversion rate”. And, that rate can be anywhere from converting 5% to about 21% of the sunlight to electricity with today’s solar panels. It’s pretty obvious that a 45 watt 5% sunlight conversion panel just isn’t going to perform as well as a 45 watt 18% sunlight conversion panel.

Factors that can affect Solar Panel Efficiency

  • The shade of any type. This is from cloudy times to the overhanging tree branches, wreak havoc on solar panels’ output. After solar cells are connected, shade on each cell is likely to affect the production of others.
  • It is recommended that solar panel systems face true south for good exposure to sunlight. The solar panel systems may face other directions though a maximum of about 30% will minimize output.
  • The solar panel type chosen will affect the efficiency of the panel system. Polycrystalline, monocrystalline, and thin-film panels that provided different efficiency levels, with the monocrystalline panels with high efficiency.

To sum up, several variables are considered while seeking the best solar panels in the marketplace.  As some panels will have high-efficiency ratings compared to others, investment in the top of the solar line equipment will not always result in high savings. The key to answering this question is based on factors such as power sizes and wattages. Other factors affecting the amount of energy the solar panels will produce are related to the landscape, slope of the roof, and home positioning.

Solar panels are a leading development in renewable resources that is growing in popularity. Though they are somewhat expensive, no one will argue that the sun is an abundant resource that needs to be used.

Because of this more and more people will go solar and soak up these renewable resources. Solar panels are used in many places such as small portable electronic devices, pool heating, supplementing power to the home, and even becoming power independent with your own grid. There are more and more uses for solar panels as technology advances. More and more people will go solar once the benefits are widely known.

When looking at those large flat panels staring at the sun you might ask, how do solar panels work? The science behind solar panels is quite involved. Simply stated the sun showers the earth with photons that are then collected by the panels. Silicon is placed beneath a layer of non-reflective glass and absorbs the sun’s photons. The atomic structure of the silicon takes the photons and converts them into DC electrical power which is then converted in to AC by use of an inverter.

Solar Panels NASA Satellite

Choosing a Solar Panel

While technology is changing rapidly there are generally four different core kinds of solar panels at the moment.

The difference between them is how they’re made which ultimately affects their efficiency. “Efficiency” means the percentage of total light that hits the panel that can be changed into electricity.

So, no matter how something is built, look for the sunlight conversion rate, or efficiency rate. Since higher efficiency often costs more, you must decide if that increase is worth the difference. It isn’t always worth it depending on what you need and how you use them. But, conversely, sometimes the cost of solar panels isn’t that much higher for a much better panel, which would then be a better choice for the solar electric power you need.

Solar Panel Technology Explained: Monocrystalline vs Polycrystalline

To go further into detail, we need to look closer at the element that is doing the work. Silicon combined with phosphorus or boron creates a charge that is positive or negative. With silicon and phosphorus, a negative charge is created. With Silicon and Boron a positive charge is formed. When the sun strikes the silicon and phosphorus combination it floods it with extra negative charges. These charges are then drawn to the positive polarity of the silicon and boron combination. This flow of electrons creates electricity. The number of solar cells present in a panel along with the quality of the materials used will determine the total electric output of the panel.

The silicon and its partners (phosphorus and boron) are placed together to form the photovoltaic cell. With advances in technology, scientists will eventually create small and more efficient panels that can be used in a much wider range of applications.

Monocrystalline (or multi-crystal) silicon panels

These panels are made from one continuous sheet of silicon with metal attached to the edges increasing conductivity. Their efficiency rates are in the 14%-18% bracket. They’re more expensive and more efficient.
Polycrystalline silicon panels

These panels have an efficiency rate of around 12%-14% so they’re not quite as efficient as the above. But they’re good. They’re put together with individual PV cells, lots of them. Metal is also attached on the edges to aid in conduction and also hold the cells together. When an individual cell is damaged you could theoretically replace it without replacing the whole panel. Their cost is less than the monocrystalline panels.

The most efficient solar panels are still the monocrystalline silicon panels. Monocrystalline solar panels are more stable and they won’t lose efficiency as fast as polycrystalline. The polycrystalline panels are sometimes cheaper but offer a lower efficiency and they also won’t last as long, thereby increasing their overall lifetime cost.

Thin film and ribbon silicon technologies

The new batches of solar panels are the thin film and ribbon silicon technologies. These are just like the ones you see in calculators and watches. They are essentially polycrystalline cells which are either arranged or poured from molten silicon. They have the same limitations as the other types of polycrystalline panels.

String ribbon silicon panels

These are put together very much like the polycrystalline panels but with added technological differences. Some people put the efficiency rate at around 12%-14%, some considerably higher. The difference in technology does allow for a lower manufacturing cost than the polycrystalline solar panels which should translate into a lower market cost.

Amorphous silicon panels

Last and least are the amorphous silicon panels with a 5%-6% efficiency rate, the lowest of any type of solar panel. They’re made from a thin flat piece of conductive metal like copper with a thin layer of silicon film over the top. They’re inexpensive to produce, relatively cheap to buy but aren’t big on energy production. Of course, if you only want to run a couple of light bulbs, etc., these solar panels could be just the thing. Amorphous silicon is being used in new ways such as in a metal roof application which has very interesting possibilities.

Sizing Solar Panels

Space required on your roof

The amount of space needed by a solar PV system is based on your present electricity needs and the physical size of the system you purchase. A small starter solar system require as little as 50 square feet and go up to as much as 1,000 square feet. Each manufacturer has its own set standard for solar panel type, size and efficiency.
About 12 m2 of roof space is required for a 1.5 kW solar panel system using silicone crystalline panels.
An equivalent system in amorphous thin film solar panels would require almost 20 m2.

More efficient solar panels use less roof area

If your location limits the physical size of your system, you may want to install a system that uses more efficient PV panels. Greater efficiency panels are more efficient per square foot and need less roof area to convert sunlight into a given amount of electric power. Depending on several factors, the cost of a system using higher-efficiency solar modules can be comparable to the same system using low-efficiency modules.

Physical Size

Solar panels come in all kinds of shapes, sizes and weights. Most are rigid but some semi-flexible ones are available, often related to a specific activity like camping/hiking in the wilderness. Solar panels don’t necessarily go up in size and weight with increasing wattage so, for instance, you can’t assume a smaller wattage panel will actually be smaller in physical size. Two panels of equal wattage may be quite different in physical size and weight. And, a solar panel can be a weighty bulky item. Will you be moving it? Frequently? Storing it in a hard to get at spot? Consider the size and the weight.  For example, maybe two 50 watt panels would be a better choice as they’re easier to move around than one large 100 watt panel. Only you know.

Price per watt

Compare solar panel pricing by price per watt. It’s the only way to get around the variations between them taking their features into consideration.