Efficiency is a crucial factor to consider when purchasing solar panels, as it measures the entire system’s ability to convert sunlight into consumable electricity. Over the past few years, solar panels have become more efficient due to the rapid development of PV technology and the prices becoming less expensive. Also, the manufacturers have created prototype solar modules that are more than 30% efficient and users can receive quotes with 20-22% efficiency from solar installers.
Earlier, in 2022, the NREL researchers achieved 47.1% efficiency using advanced cell structures.
Before you find out the best type of solar panels available in 2024, you need to find out if factors like rain and cold weather affect the system’s efficiency or not by understanding its design, inclination, and temperature. This will help you implement the best methods to optimize. By the time you travel through this guide, you will gain major knowledge on how inverters and thermodynamics influence the overall efficiency and the methods to minimize reflectance.
Solar Panel Efficiency Explained
Solar panel efficiency can be defined as the capacity of a PV module to convert sunlight into electricity. In other words, it is the ratio of electrical power output to the solar energy input expressed in terms of percentage.
A solar panel with 20% efficiency will convert 20% of sunlight into electricity. For example, a 400-watt solar panel with 20% efficiency will generate 80 watts of electricity under perfect sunlight conditions (400 watts x 20%= 80 watts).
Owning high-efficiency solar panels results in several benefits such as:
1. Instant payback: Since the average payback of solar panels is 6–10 years, operating at peak efficiencies helps to reduce the gap instantly.
2. Space efficiency: The premium quality solar panels provide enhanced power production that requires fewer panels for installation, thereby resulting in less crowding and large roof space saved.
3. Lower environmental impact: As high-efficiency modules quickly repay the production energy, the environmental impact of producing solar panels is reduced. This is because a few number and most efficient panels can be produced to generate electricity for the same amount of sunlight.
4. Return on Investment (ROI): Highly efficient solar panels increase your monthly savings and offer you the highest possible return on investment (ROI).
What Are the Most Efficient Solar Panels in 2024?
Here are the most efficient solar panels in 2024 tabulated below in detail:
| Company | Model | Maximum Efficiency | Cost ( in USD) |
| SunPower | M Series 440-watt | 22.8% | $2.98 – $3.73 per watt |
| REC | Alpha Pure RX 475-watt | 22.6% | $2.50 -$3.46 per watt |
| Jinko Solar | Eagle 54 G6R 440W | 22.53% | $2.60 per watt |
| Qcells | Q.TRON BLK M-G2+ (440W) | 22.5% | $2.32- $3.16 per watt |
| Maxeon | 3 BLK-R 420 W | 22.2% | $2.94 – $4.42 per watt |
| Panasonic | EverVolt HK Black Series 410 W | 22.2% | $2.91 – $3.644 per watt |
| Silfab | Prime NTC (430W | 22.1% | $0.70 per watt |
| Canadian Solar | HiHero (445W) | 22% | $0.70 per watt |
The cost may vary depending on the roof characteristics and the requirement for additional equipment.
Factors That Affect the Efficiency of Solar Panels
Several factors along with the inverter, reflectance, and thermodynamics influence the efficiency of solar panels which include their types, design, inclination, and temperature.
The Type of Solar Panels
These three main types of solar panels differ in terms of materials, efficiency, and cost:
1. Monocrystalline solar panels:
- Materials: Manufactured from the single crystal structure of highly pure silicon.
- Efficiency: Highly efficient (15–22%).
- Cost: High-priced ($1- $1.50 per watt) due to pure quality silicon and manufacturing complexity.
2. Polycrystalline solar panels:
- Materials: Multiple silicon layers are melted to form wafers for the solar panel.
- Efficiency: Less efficient than Monocrystalline (15 – 17%).
- Cost: Affordable expense ($0.75–$1 per watt).
3. Thin Film solar panels:
- Materials: The most commonly used materials in thin film solar cell technology are cadmium telluride (CdTe), copper indium gallium selenide (CIGS), amorphous silicon (a-Si), and gallium arsenide (GaAs).
- Efficiency: Less efficiency (7–10%) than Monocrystalline and Polycrystalline modules.
- Cost: Less expensive ($0.50 and $1.50 per watt) than Monocrystalline and Polycrystalline panels.
Despite the higher price, Monocrystalline solar panels are highly efficient and translate huge amounts of energy with few panels on your roof.
Design of Solar Panels
The layout and configuration of cells within a solar panel influence its efficiency due to the design and arrangement of various components within the solar cells such as the p-n junctions, metal contacts and passivation layers. Also, the enhanced design patterns of the mechanism maximise the separation, collection, and transportation of charges leading to higher efficiency.
Typically, certain colours like dark blue or black colour in Monocrystalline solar cells are more effective in maintaining the panel efficiency than the light bluish colour of the Polycrystalline cells. This is because the blue or black reflects less light to enhance the power output.
Inclination of Solar Panels
The angle or tilt of solar panels affects their ability to capture sunlight and produce energy in the following ways:
- Solar Panel Tilt Angle measures the overall performance of the solar panel system as it determines the sunlight’s angle to strike the panel’s surface. You need to ensure that adjusting the tilt angle ensures panels absorb maximum sunlight to increase energy efficiency and reduce the payback period.
- Optimal Tilt Angle depends upon the location’s latitude. If the solar panels are positioned according to the tilt angle seasonally, you can harness maximum solar energy throughout the year.
You need to consider several factors while planning for solar panel installation to increase the sun’s exposure in different seasons of the year which include:
- Avoid shading and obstacles to increase efficiency.
- Select the best area where the panels can trap maximum sunlight.
- South-facing roofs in the Northern Hemisphere.
- The optimal Angle should match the latitude of your area.
- Flexible mounting system to change the panel’s angle throughout the year.
Temperature
Mainly, solar panels become less efficient at higher temperatures due to the built-in physical properties of the semiconductors used. Higher temperatures increase the kinetic energy of charge carriers within the cells and reduce the output voltage, thereby lowering the panel’s efficiency. The optimal temperature to operate solar panels is around 25°C.
However, a manufacturer has alternative methods to address the challenge of temperature-related efficiency losses such as:
- Ensuring proper ventilation and airflow by allowing considerable spacing around the solar panels helps to release extra heat and avoid the increase in temperature.
- Proper cooling measures like pergolas or canopies prevent direct exposure of panels to harmful sunlight.
- Anti-reflective coatings and innovative materials during the manufacturing process increase light absorption and lower the reflection rate.
Inverter Efficiency
An inverter’s efficiency can have an overall impact on the solar panel system in several ways:
- Conversion Efficiency determines how the inverter from DC power to AC power is used and the energy losses during the process.
- Load Dependence of an inverter indicates its operation with varying efficiency levels. Typically, inverters at a specific load level reach their peak efficiency of 20% to 30%. The efficiency of an inverter decreases when the load is too high or low.
- CEC Efficiency refers to the ratings set by the California Energy Commission to measure how the inverter performs under varying conditions by handling fluctuating power levels and voltages.
- Peak Efficiency is an indication of how best the inverter converts the DC energy from your solar panels into the AC energy for your house.
There are also so many important things about solar inverters you should know.
Out of several strategies, a few are listed below that help to mitigate energy loss during the DC-to-AC conversion process:
1. Best quality and highly efficient inverters result in less electrical loss during the conversion process. For instance, 20% of electricity is lost in an 80% efficient inverter whereas only 2% of energy is used up for a 98% inverter.
2. MPPT Charge Controllers help to track the maximum power point of the PC array that regulates the power flow to the inverter.
3. Short extension cords connected to the inverter and batteries in the solar PV system diminish power losses.
4. Larger Gauge wires have minimum resistance to handle more current and minimize power losses during the conversion process.
5. Placing inverters close to solar panels helps to reduce losses. Conversely, if the electricity has to travel longer distances there will be higher obstructions in the flow of current.
Reflectance Efficiency
Reflectance plays a crucial role in solar panel efficiency as surfaces with low reflectivity absorb less sunlight. As a result, lowering the reflectance rate becomes important to optimize the performance of solar panels by implementing these best strategies:
1. Anti-reflective coatings play a crucial role in minimizing the reflectivity of solar panels to reduce glare.
2. Textured glass reduces the reflectance of PV panels by 1–2%.
3. Adjusting the panel’s tilt a few degrees east or west helps to diminish the reflectance at a significant portion of yearly energy production.
4. Dark-coloured solar panels lower the reflectivity rate.
5. Altering the panel’s layout reduces visibility, thereby enhancing the maximum absorption rate of sunlight.
Thermodynamic Efficiency
The thermodynamic efficiency limit for solar panels is the possible maximum theoretical conversion of sunlight into electricity. Also known as the Chambadal-Novikov efficiency or Carnot cycle, the maximum limit is 86% based on the temperature of photons released by the sun’s surface.
These are certain ways to improve the thermodynamic efficiency of solar panels:
1. Thermodynamic solar panels absorb heat from sunlight and ambient air. These panels can be mounted on walls or roofs that do not require direct sunlight.
2. Clean your solar panels to remove the accumulation of dirt and debris. Therefore, the annual cleaning of panels might prevent the decline of thermodynamic efficiency by 5% to 20%.
3. Promoting the Dispersion of Light in the visible portion of the energy spectrum can increase the thermodynamic efficiency of a solar panel.
4. Protection of the back Surface is another technique that can be used to improve the thermodynamic efficiency of solar panels.
5. Eliminating shading like nearby objects, trees, buildings or other objects can ensure increased efficiency.
How Can Solar Panel Efficiency be Optimized?
You can follow these methods to optimize the solar panel efficiency:
1. Monitor the system: Efficiency monitoring is another essential feature of solar panel maintenance that requires regular inspection and examining performance data to rectify any issues that might affect the energy output.
You can detect any issues at an early stage by tracking efficiency and taking preventive actions before they lead to severe losses in energy production. Additionally, you have to gather data on other factors such as temperature, irradiance levels, shading and soiling.
2. Ensure maximum sunlight exposure: A proper tilt angle of solar panels plays a crucial role in maximizing the sun’s exposure depending upon the latitude of the installation area. For instance, a location with 30 degrees latitude will have an optimal angle of 30 degrees. You can adjust the panel’s tilt angle and increase the energy output by using the solar tracking system regardless of its expensive price
3. Regular cleaning and maintenance: To minimize the repair cost over time and maximize the solar panel system efficiency, you need to perform regular cleaning and ensure its maintenance. By failing to do so, you might face several issues such as diminished energy production, loss of electricity bill savings, permanent damage to solar panel systems and reduced lifespan.
Does Rain Affect Solar Panel Efficiency?
Yes, The efficiency of solar panels is reduced in rainy conditions, but they continue to generate less electricity when compared to sunny days.
These are the possible ways by which precipitation affects efficiency:
1. Net metering: If you have a net metering plan in your residing area, the additional energy produced during sunny days can compensate for the energy consumption during cloudy or rainy days.
2. Cleaning Effect: Rainwater helps to clean away the dirt and debris accumulated on the solar panel surface.
3. Light transmission: The rainwater decreases light transmission and blocks sunlight from reaching the photovoltaic cells.
4. Snow and Ice accumulation: If there is any snow or ice accumulated on the panels, it can damage the solar cells or panel structure. Also, the reduced sunlight exposure diminishes the energy output.
Does Cold Weather Affect Solar Panel Efficiency?
Yes, Solar panels can operate effectively in cold weather conditions, and sometimes they might function more efficiently on colder days rather than sunny conditions due to the following reasons:
1. Withstand a certain weight: The majority of solar panels are manufactured in such a way as to withstand a certain amount of weight. Moreover, snow wouldn’t be heavy enough to cause problems since all solar panels undergo pressure tests before receiving ratings. Consequently, you can figure out that the high-pressure ratings indicate the capacity of solar panels to bear the weight of snow.
2. Light Reflection: The white snow on the surface of solar panels improves the PV performance by reflecting more light. It means that your panels can produce more power output for shorter days in winter than in summer.
3. Temperature: The PV cells can lose efficiency and reduce power output if the temperature increases above a certain limit. Especially, the issues are more during hot summers if the temperature reaches upto 50°C or more which affects the electricity generation of solar panels. Contrarily, the colder winter temperature increases the conductivity of the PV components resulting in increased levels of electrical current flow and enhanced power output.
However, the exact impact of cold weather on the efficiency of solar panels varies based on several factors like sunlight intensity, the panel’s angle and the type of solar cells used in the panels.
Are More Efficient Solar Panels More Expensive?
Yes, Highly efficient solar panels are more expensive due to the usage of advanced technology and high-quality materials. Also, such panels can generate more amount of electricity in less space.
Although the initial cost may be higher, you can gain long-term benefits by saving electricity bill amounts to a great extent.
Finally, the higher efficiency panels produce massive power when compared to the same size of the lower efficiency panels.
Ray is an avid reader and writer with over 25 years of experience serving various domestic and multinational private and public energy companies in the USA.