According to Geoscience Australia, the Australian government’s official source for solar energy data, the continent of Australia receives 50 million petajoules of solar-based radiation over the course of one year – an amount that is over 10,000 times the energy consumption demands of the entire country.
Despite these impressive statistics, the solar energy market is one of Australia’s fastest-growing industries, but solar power still only accounts for 0.1% of the country’s total energy consumption. However, with an increase in government-sponsored rebate programs and the continued innovations of the solar industry, solar power usage in Australia is expected to keep increasing well into the future. This begs the question – how efficient are solar panels? And what is energy efficiency? Below we cover everything related to solar panel efficiency levels in Australia, how solar energy works, and other important topics.
What Is Solar Panel Efficiency?
Solar panel efficiency measures how much sunlight a panel converts into usable electricity. A higher solar panel efficiency rating means a greater percentage of the sun's energy becomes power for your home. As a result, a high-efficiency system requires fewer panels than a low-efficiency one to produce the same amount of electricity.
For example, a solar panel with 20% efficiency converts 20% of the sunlight hitting it into electricity; the remaining 80% is lost as heat or reflection.
What Is Solar Panel Module Efficiency?
Module efficiency is the percentage of sunlight energy that a complete solar panel converts into usable electricity under standard test conditions (STC: 1000 W/m², 25°C cell temperature). It is calculated as:
Module Efficiency (%) = (Power Output / (Area × 1000 W/m²)) × 100
For example, a 400W panel with an area of 2 m² has an efficiency of 400 / (2 × 1000) = 20%.
In real‑world modules, gaps between cells, busbars, and glass reflection lower the value. Typical module efficiencies today range from 16–19% for polycrystalline, 19–22% for standard monocrystalline, and up to 22–24% for premium monocrystalline designs.
Higher module efficiency means more power in less space, which is ideal for limited roof areas, while lower‑efficiency panels are often cheaper but need more room. Temperature, shading, dirt, and aging all affect real‑world performance.
Factors Affecting Solar Panel Efficiency
There are numerous factors that go into quantifying a solar panel’s efficiency rating – design, manufactured materials, components, and even considerations such as the placement of the solar panels on your property, their angling, and other environmental concerns. All of these factors play an important part in determining the efficiency level of a solar panel system.
Solar Cell Types
Solar cells are the material that is responsible for absorbing power from solar PV rays. We’ve already touched on the three main solar cell types – polycrystalline, monocrystalline, and thin-film. Here is a brief overview of each solar cell type:
- Monocrystalline: The “mono” refers to the fact that these solar cells feature a structure with a singular silicon crystal base – essentially being manufactured using one of the purest forms of silicon available. These solar panels are the most efficient on the market, but because of their high-intensive manufacturing process, they cost more than polycrystalline or thin-film panels.
- Polycrystalline: You have probably seen these common solar panels, they are easily distinguishable from their monocrystalline cousins due to their classic blue appearance. Made using a collection of silicon crystals, as opposed to the single silicon structure of monocrystalline. These panels are the mid-range offering, and have a lower efficiency rating compared to momocrystalline panels.
- Thin-Film: Thin-film panels are considered the lowest-cost option for solar panel systems. They have a lower efficiency rating compared to crystalline panels, but make up for this with their decreased price points. Thin-film panels are available in four different options: Gallium Arsenide, Amorphous Silicon, Copper Indium Gallium Selenide, and Cadmium Telluride. These solar panels typically require more maintenance than other options, and because of their lower efficiency levels, a thin-film system will require more actual panels than a system that utilizes crystalline paneling.
Solar Cell Technologies
Solar cell technology has advanced since the early days of the industry, and now there are four main types of cells available for both commercial solar energy systems and solar energy systems for home properties.
- IBC Cells: Otherwise known as Interdigitated Back Contact cells, are known as the ultra-efficient cell option, with efficiency ratings commonly nearing upwards of 29%. Because they don’t utilize metal ribbons to fasten the cell onto the panel, they can absorb more sunlight (thus leading to higher efficiency).
- PERC Cells: PERC stands for Passivated Emitter and Rear Contact. They feature an additional layer of paneling beneath the first panel, which allows for a greater potential of capturing more of the sun’s rays. The second layer also serves an additional purpose – it prevents the aluminum backing of the panel from generating heat which can lower efficiency.
- HJT Cells: Heterojunction cells feature polycrystalline technology coupled with thin-film paneling, where the main crystalline silicon layer is placed between additional layers of silicon which can help the panel absorb more sunlight. 25% efficiency ratings and up are common for HJT cells.
- Half-Cut: These cells are unique in that during the manufacturing process, the cells are divided into two, which doubles the number of total cells on one panel. The way these cells generate efficiency is by reducing the amount of distance that energy needs to travel between cells. These panels also feature a higher resistance to heat than other types of panels.
To install a highly efficient solar panel system, click here for more information.
Sun Hours
Irradiance, commonly referred to as sun hours, is a major factor in how efficient a solar panel system will be. Simply put, the higher the level of irradiance (or the more sun hours a system receives), the higher amount of power it will be able to generate. Different states in Australia are shined with different lengths of sunlight. Check out Average Peak Sun Hours in Australia by State to find out the sun hours in your region.
Working Temperature
Believe it or not, there is an optimal temperature range for solar panels. Contrary to popular belief, a solar panel system won’t operate at peak efficiency in an extreme-heat environment. In fact, lower temperatures often predicate a system delivering more power at better efficiency levels. If the temperature is too hot or too high, the efficiency of a system starts to deteriorate. Once a panel is exposed to temperatures beyond 25°C, its efficiency will start to lower as the temperature increases. Panels will include specific efficiency details regarding temperature in their included documentation.
Shading
This should go without saying, but the more exposed a solar panel is to shading, the less effective it will be. Panels operate their best in high-sun environments, and if they are placed in an area with excessive shading, tree coverage, or clouds, their efficiency will decrease. However, inverters such as microinverters and string inverters can diminish the influence of shading to some extent. Check out “Do solar panels work when there’s shade?” for more.
Angles Against the Sun
One of the more overlooked aspects of installing a solar system is the angle that the panels are positioned. It’s important to ensure that your panels are positioned in an area that has maximum sun exposure for your area of the world, as well as using the right “tilt” – a 20-degree angle is the usual recommended tilt angle for maximum sun exposure.
The Most Efficient Solar Panels in Australia
Looking for the highest efficiency solar panels available? Renogy has you covered. Our selection of premium-grade monocrystalline solar panels is unmatched and features the latest in leading-edge solar panel innovations from the industry’s best brands and manufacturers.
FAQ
Do solar panels lose efficiency over time?
The average lifespan for a solar panel system ranges between 20 to 30 years. Near the end of a panel’s life, its efficiency will have been reduced by about 12% or 15% – this means that solar panels, on average, lose about 0.5% efficiency per year.
What does 20% efficiency on a solar panel mean?
A 20% efficiency rating on a solar panel means that the solar panel is able to convert 20% of the raw solar power it collects into usable energy.
What is the typical efficiency of a solar panel?
In modern times, efficiency ratings fall around 20% for most leading solar panel brands and products.
Will solar panels ever reach 50% or 90% efficiency?
50% solar efficiency has been achieved. But it is still a long way to commercialize due to all kinds of technological limitations. It is difficult to say whether or not solar panels will reach a 90% efficiency rating in the near future, but with the constant advancements in PV technology being uncovered on a near-daily basis the future is very bright for solar panel efficiency technology.
