When you invest in a solar power system, your goal is to harness the sun’s energy to power your home. The process starts with the photovoltaic cells in solar panels, which collect sunlight and convert it into energy. The amount of electricity a solar panel can generate from direct sunlight is referred to as “efficiency.” The more efficient your solar panels are, the more electricity you can generate from available sunlight.
Consumer solar panels for electricity generation generally use the same technology. Photovoltaic cells absorb sunlight and convert the sun’s power into electricity. Many factors contribute to how efficiently a solar panel captures available sunlight and turns it into electricity.
For most residential solar power users, the available surface area to install PV panels to capture sunlight is limited. That’s one reason why efficiency is so important. Ideally, you want to harvest the most electricity using the least number of solar panels and installation space.
Here’s a complete guide to solar panel efficiency. Knowing which panels can deliver the maximum electricity by surface area is essential to maximizing your solar investment.
How Efficient Are Solar Panels?
Today’s solar panels generally reach an efficiency of 15-20%. The conversion efficiency means that the photovoltaic panels can convert about 20% of the total sunlight captured into usable energy.
Efficiency has increased in recent years, and some photovoltaic panels have reached as high as 35% efficiency. That said, these come at very high costs; the low 20s is considered the peak efficiency available for residential use.
What Is Solar Panel Efficiency?
In simple terms, PV solar panel efficiency measures the percentage of direct sunlight received that is converted into electricity.
Solar panel efficiency percentage represents sunlight conversion in ideal conditions. In real-world applications, other factors may impact efficiency.
Even though no PV panel can operate at maximum efficiency at all times, it’s helpful to know the rating. You can use the efficiency rating, rated power, and average peak sunlight hours in your location to build an array that powers your entire home.
How Solar Panel Efficiency Is Measured
Solar panel efficiency measurements factor in the amount of sunlight converted into electric or thermal energy. A PV panel can’t catch all the wavelengths of solar energy, so it loses much of the total power provided as heat. Additionally, some sunlight passes through the photovoltaic cells uncaptured or reflects off the panel’s surface.
The portion of sunlight the cell captures and converts to DC electricity is the basis for the efficiency metric. Certain photovoltaic compositions are more efficient than others, with the more advanced monocrystalline solar panels reaching up to 23% conversion efficiency.
How Solar Panel Efficiency Affects the Amount of Energy Produced
The more efficient a solar panel is, the more electricity it can produce. A more efficient solar panel needs less direct sunlight each day to provide the power you need. A less efficient panel needs to receive more direct sunlight.
Once you know the solar panel efficiency, rated power, average hours of peak sunlight in your location, and electricity consumption requirements, you can better determine the number of panels you need to meet your requirements.
Factors That Affect Solar Panel Efficiency
Many factors come into play that affect the efficiency of your PV solar panels. Some you can influence, but all play a role in the efficiency of your system.
- Temperature—Solar panels are most efficient between 59 and 95 degrees Fahrenheit (15°C – 35°C). Very low or extremely high temperatures can reduce the efficiency of your solar array.
- Solar Irradiance—A decrease in direct sunlight reduces the efficiency and rated power output of your PV panels.
- Cell Quality—Higher quality photovoltaic cells provide higher efficiency for your panels. Monocrystalline panels are slightly more expensive but offer the highest sunlight conversion rate — leading to savings over time.
- Panel Age—Solar panels can last over 25 years, but they lose some of their efficiency as they age. If you’re relying on a warranty to protect your investment, be sure you understand the terms and efficiency level it protects.
- Panel Orientation and Tilt—Optimizing the panel’s angle and position relative to the sun significantly affects the panel’s efficiency. You want to position it to receive the maximum direct sunlight available during the day. In some applications where the roof limits optimal orientation and tilt, portable solar panels may be better to take advantage of peak sun hours. Solar trackers can also be a viable option.
- Shading—Shading from trees or cloud cover reduces your efficiency considerably. You should work to clear obstructions. PV panels still operate on cloudy days, but the indirect sunlight makes for a less efficient panel.
- Cleanliness—Dirty panels still function but prevent some sunlight from being absorbed. Cleaning off your PV panels regularly can go a long way toward keeping them operating more efficiently. Clearing them of snow or ice accumulation is also crucial in cold environments.
Types of Solar Panels and Their Efficiencies
Some factors that impact solar panel efficiency, like the weather, are beyond your control. Solar panel efficiency is an even more crucial metric in locations that don’t always have ideal conditions for capturing solar power. Solar panel construction and manufacturing quality can significantly impact how much electricity you can generate.
Here are the most common types of PV solar panels.
The photovoltaic cell in a monocrystalline solar panel consists of a single, pure individual silicon crystal. Due to their construction, these are the most efficient solar panels for residential solar power systems.
Monocrystalline panels typically reach efficiencies of around 20%. EcoFlow’s rigid and portable solar panels are monocrystalline and can achieve an industry-best efficiency of 23%.
Polycrystalline solar panels consist of several pieces of silicon broken into fragments and then melted together. This manufacturing process creates solar panels that are less expensive but also less efficient. Polycrystalline panels typically fall in the range of 10-15% efficiency.
Thin-film solar panels can consist of a few different materials:
- Amorphous silicon
- Cadmium Telluride
- Copper Indium Gallium Selenide
Flexible solar panels utilize very thin layers of photovoltaic material. While they carry the advantage of being thinner and more flexible than other types of panels, they are the least efficient, with an efficiency rating between 7-18%.
How to Maximize Your Solar Panel Efficiency
Purchasing the most efficient solar panels based on manufacturing quality and process is the best starting point. Beyond this, you can take steps to get the highest energy conversion possible from your solar panels.
Proper Panel Orientation and Tilt
Installing your solar panels provides your first opportunity to maximize efficiency. If you live in the northern hemisphere, this will mean a south orientation because the sun’s path runs across the south from sunrise to sunset. You will also want to tilt your panels to get the most direct sunlight possible, ideally 4-6 hours per day.
Regular Cleaning and Maintenance
Clean your solar panels and their connection points every six to twelve months. You may need to do so more often if you live in areas with more dust or air pollution than average. In addition, plan to clean them off after extreme weather events that may lead to snow and ice accumulation.
Proper Shading Management
If you have trees that could obstruct your solar panels, trim the branches periodically. When branches obscure direct sunlight, your solar power system’s efficiency will be negatively impacted. Regular pruning and trimming of overhanging foliage helps keep the sunlight’s path clear.
EcoFlow’s monocrystalline solar panels deliver the best manufacturing-based efficiency from the start. You can take many measures to ensure your solar array delivers as much power as possible. Still, solar power efficiency is a valuable metric for understanding the ceiling of how much electricity your panels can produce — even under ideal conditions.
Monocrystalline solar panels provide the highest efficiency, often giving you 20% efficiency or even higher. EcoFlow’s 400W rigid solar panel delivers an efficiency of 23%. You can take additional steps to ensure your solar panels reach peak efficiency, including positioning at optimal angles and clearing the sunlight’s path to ensure the maximum amount of direct sunlight hits the panels.
Solar panels are generally most efficient at 59-95 degrees Fahrenheit (15°C – 35°C). Panel temperatures of 150F or above reduce efficiency, as will extremely cold temperatures. If you live somewhere with extreme temperatures, you may need additional solar panels to meet your electricity consumption requirements.
In the northern hemisphere, you can increase the efficiency of your solar panels by setting them at a southern orientation and angling them to receive the most direct sunlight during the day. In the southern hemisphere, the opposite applies. Also, keep your solar panels clean and clear tree branches and other obstructions that can impede direct sunlight from reaching the panels.
You should clean your solar panels every six to twelve months to keep the panels operating efficiently. If you live in a dusty or windy location — or one subject to extreme weather events — you may need to clean your solar panels more frequently.