What is a good efficiency rate for solar panels?

Solar cell efficiency is the rate at which a solar panel transfers the sunlight via photovoltaics into electricity. The average cell efficiency of a solar panel is between 15 – 22%. The level of efficiency varies between manufacturers. The higher the efficiency of a solar panel, the more solar power it will produce per square metre. Higher panel efficiency has been recorded in laboratories; scientists at the National Renewable Energy Laboratory (NREL) have a developed a six-junction solar cell that converts sunlight to electricity at 39.2% under one-sun illumination.

Most efficient solar panels

The best quality solar panels tend to be the most efficient. The most efficient residential solar panel available in Australia is SunPower’s Maxeon 3 400W module, it boasts 22.6% efficiency. Both LG and REC also produce high efficiency solar panels well above 21%, then there is a gap to a host of manufacturers whose panels sit just above 20% efficiency. The table below shows the most efficient solar panels:

*The solar panels in this table are all panels suitable for residential installation.

Solar panel efficiency is one indicator to the level of quality of the panel, but not the only one. Our solar panel buying guide has tips on what to look for in a good panel including important warranty information.

Solar panels power rating

Solar panels are given a power rating in Watts, based on the amount of electricity they can produce in one hour of peak sunlight. However, these ratings are classified under ideal conditions in a laboratory, and therefore don’t represent the amount of power that could be expected of that panel on a day-to-day basis. So a 380W panel installed on a household rooftop, is not going to produce 380 Watts of electricity, even in peak sun.

Factors that affect the efficiency and output of a solar panel

There are several factors that affect the panel output and efficiency of a solar panel. All of these factors must be considered when calculating solar power at any given location.

Manfacturer’s output tolerance

Most solar panels have an output tolerance +/- 3%, which means that the manufacturers panel will perform within 3% of its Watts rating.

The effect of dirt on solar panels

Dirt and grime also affect the efficiency of a solar panel. This varies from panel to panel, however, it’s best to factor in a loss of performance. In all of our calculations, we equate the loss of efficiency due to dirt and grime to be 5%. If you were to clean your panels regularly, they would perform better.

Temperature derating

Solar panels are affected by temperature. The hotter the panels get, the less efficient they become. We cover this topic in great detail here, but the short of it is: the temperature coefficient, ambient temperature, as well as the type of installation all affect the efficiency of the panel and therefore solar panel output.

Roof tilt and orientation

The direction that solar panels face, and the angle that they are mounted, also have an affect on the output of the panel. If they are not positioned at the optimum angle and direction, then the panels will not produce rated output for that location. This is a must when accurately calculating solar output.

Inverter efficiency

The inverter converts Direct Current (DC) into Alternate Current (AC), so that the energy produced by solar panels can be used to power your home’s electricity. This process is not 100% efficient. Whilst inverter efficiency technology is improving, it can still account for as much as an 8% loss in efficiency. We allow for an average of 5% in all of our calculations.

Battery inverter efficiency

If you have a hybrid system with a solar battery, your battery will not operate at its rated Wattage. Inverter efficiency for batteries is in the realm of 92%, representing an 8% loss.

DC cable loss

There may be a small voltage drop between the solar panel system and the inverter, this can account for efficiency losses of around 1-2%.

AC cable loss

Similarly, the connection between the inverter and the electricity switchboard can result in a drop in voltage leading to a small loss in the efficiency of the system.

When accurately calculating solar panel output for a given location, all of these factors should be accounted for. All of our calculators that ask for your postcode factor in the affect of tilt and orientation, and all of the solar panel efficiency factors.

With at least another 4 to 5 billion years of solar energy bombarding the planet daily, harnessing the power of the sun for electricity can be one of the best options for those seeking cleaner energy sources.

While the prospect of cutting down on your monthly energy expenses through the latest developments in solar technologies may seem like a great idea, the initial investment may have you questioning if solar power is really worth it.

To better understand how you, and many others, can directly benefit from an installation of solar energy systems, the efficiency of the panel you choose should be considered, but that does not mean a more efficient panel will translate into better economic benefits for you personally.

A variety of factors including panel placement, geographic location, the architectural design of your roof, temperature, and the amount of shading on your building will determine if upgrading to a solar energy system is right for your business, or home.

Efficiency in solar panels is simply the measurement of energy output in a given surface area. The more efficient a panel is, the less space it will take up on your roof. However, choosing a more efficient solar panel may not always be the most cost-effective decision available.

Depending on location, installation costs will vary. Arizona is one of the leading states in solar energy, and it offers a range of incentives to encourage consumers. The Grand Canyon State is also one of the best states to utilize solar power systems as Yuma is ranked the sunniest city in the country by NOAA.

Efficiency of Solar Panels

The more efficient the photovoltaic solar panel, the more energy output it will have per amount of light energy hitting the cell, which will in turn take up less surface area to meet your energy requirements.

Today, most solar panels provide an energy efficiency rating between 11 and 15 percent, which is the percentage of solar energy that is being converted into useable electricity.

While it may seem like a low percentage, advancements in solar energy technologies are continually being made, and modern panels can more than cover the energy requirements of most commercial and residential needs.

Today, researchers are continually trying to improve the efficiency of photovoltaic technology. Scientists have now achieved a record of 40 percent efficiency by utilizing multi junction cells that are tuned to capture different frequencies of light on the electromagnetic spectrum. While these are currently the most efficient solar cells that have been created, they are not yet available to the general public.

If you have a smaller roof and limited space, a more efficient solar panel may be the right choice for you. Because of their higher efficiency, these panels may be slightly more expensive, but they will still meet the energy requirements you need.

However, if you have a larger amount of space, you may be able to achieve your energy needs with less efficient and less expensive panels to help save on your installation costs. Considering the overall cost of the panels and the kilowatt production can help you pick which is best for your installation.

Photovoltaics and Types of Solar Panels

The industry standard for solar electric systems is based on photovoltaic, or PV, technology, which converts sunlight into electricity. Multiple solar cells are interconnected to create a module, which comprises the panel.

Each panel is usually connected together in a system in which electricity is sent to an inverter to provide the power needed to run household electric devices. Efficiency is often dependent on the design of the panel and how it is engineered to capture different frequencies of light energy. Consider the following designs:

• Monocrystalline Silicon Panels - The most efficient type of photovoltaic solar panel available today is currently monocrystalline, or single, silicon panel. Because of the higher silicon content used in the design, they are more expensive than alternative types of panels. More energy is converted into electricity, so fewer panels are needed in most roof installations to meet the same power requirements. These types of square-shaped panels are ideal for roof mounted solar electric systems.
• Polycrystalline Silicon Panels - With lower amounts of silicon utilized in polycrystalline, or multi-layered, silicon panels, they are often cheaper than their more efficient counterparts. They implement a design to help reduce this efficiency loss, allowing them to be utilized on roof mounted systems. This makes them ideal for larger projects and installations because they cost less. Polycrystalline silicon panels are also resistant more resistant to heat.
• Building Integrated Photovoltaic Panels - Appearance is an important aspect of a building. As with many historic buildings, or ones that feature unique architectural designs, owners might be hesitant to alter the distinctive character of a structure by installing a solar electric system. To help mitigate the aesthetic changes that solar panels might bring, building integrated photovoltaics are available. While they may be able to keep the look of traditional roofing, these types of panels are more costly and less efficient than the alternatives.
• Thin-Film Solar Cell Technology – Thin film cells are a newer photovoltaic technology that consists of one or multiple layers of thin films of photovoltaic cells that are laminated to existing material, such as metal roofing or glass windows. These photovoltaic films are very thin allowing them to be lighter and more flexible compared to other PV systems. While thin-film technology is extremely versatile, it comes at a cost. Thin-film systems are less efficient and can degrade faster than conventional solar systems, but are improving with technology advancements.

Factors That Can Impact Efficiency

Solar power efficiency depends on a variety of factors including proper installation and assessment of the structure. Hiring a professional to inspect the structural design and location of your building is essential in determining what type of installation will best meet your requirements and provide you with the long-term economic benefits of solar power. Empire Renewable Energy offers a range of services for commercial and residential applications:

• Most solar panels are designed with a layer of protective glass over the cells, which sunlight must pass through. The amount of energy harnessed is dependent on the angle in which light is passing through, as well as the reduction of reflectivity of the glass.

• Proper installation of a solar panel is significant to capturing the maximum amount of sunlight. The angle of the panel and the amount of light hitting it are both important factors that will help you maximize efficiency.

• For roof mounted panels, the slope of the roof will impact how much sunlight is hitting the panels throughout the day. Large commercial installations can compensate for the movement of the Earth by installing solar tracking systems, but due to the expense, they are not typically installed for residential use.

• Temperature can impact the overall output of a solar cell. Higher temperatures can reduce output and lower efficiency. Some solar panels are designed for warmer climates, where efficiency must be maintained as temperatures climb. Ensure you select the right panel that is best suited to your climate, so you can enjoy a better return on your investment.

• Even a small shaded area on solar panels can greatly reduce their output. Since panels are often wired together in a system, even a small shadow on one panel can drastically reduce the system's overall energy production. It is ideal to install panels in a way that no shadows will fall on any of them. In some situations this may be difficult to avoid, so alternatives are available to help maintain efficiency.

Types of Solar Installations Offered by Empire

Deciding on the type of installation for your business or home is also essential if you want to get the most out of your investment. As space and architectural designs vary for each customer, there are many options available:

• Roof Mount Solar Installation - Roof mount installations are a popular option for both commercial and residential customers. They offer a way to capture the solar energy that naturally hits your rooftop every day.
• Pole Mounts Solar Installation - For those with limited roof space, pole mounted systems can be installed, but they require a designated area of land for proper installation.
• Ground Mounts Solar Installation - Similar to pole mountings, ground mounted systems are placed in yards and fields. They are useful for those who have limited roof space or own the large amount of land required to maximize the benefits of solar energy systems.
• Shelters Solar Installation - For those looking to cut down on energy expenses, alternative outdoor structures such as gazebos and structural awnings can be equipped with solar energy systems.
• Parking Lot Canopies Installation - For installations that house large parking areas, solar energy can be harnessed to reduce electricity expenses and provide shade to customers in designated parking areas.
• Shade Awnings - For buildings with limited space, replacing traditional awnings with solar panels is a great way to lower monthly energy expenses while still providing the same function.
• Detached Garage Solar Installation - For many, roof space and parking space may be limited. Detached garage installations, however, can still provide economic benefits to residences where roof mount installations are not possible.
• Building Integrated PV Systems - For some buildings, the historic or general aesthetic is vital to the structure's architectural character. Solar installations that are integrated into the building's design can help minimize changes to the appearance while still providing the benefits of solar energy systems.

Most Efficient Solar Panels Offered by Empire

In order to provide Arizona residents with the most efficient solar panels on the market, Empire Renewable Energy has partnered with SunPower.

SunPower modules have a 40-year lifespan, and their solar cells offer the best performance on the market with an operating efficiency of up to 24 percent. If you utilize SunPower solar cells, you'll see a faster return on your investment with approximately 20 percent more energy output over similar products.

With some of the highest ratings in the industry, SunPower offers superior performance and longevity when compared to similar sized panels. SunPower also holds the world record for the highest efficiency silicon solar panel.

The Benefits of Solar Power

For the mass majority of business owners and homeowners, solar power is a great option to reduce monthly energy expenses and increase property values.

Arizona offers numerous incentives to those looking to install solar power systems. In addition, the federal government is also encouraging green-energy alternatives and offering tax credits and loans to those looking to upgrade to a solar system.

As the demand for solar energy has increased, the technologies have advanced while the prices have declined drastically since the late 1970s. It is now cheaper than ever before to install a solar energy system for your home or business.

While the initial investment to install a solar electric system will greatly depend on the size of the installation, the overall savings is worth it to most customers.

In addition to reducing monthly expenses, most roof mounted systems are designed for longevity and require very little maintenance.

Inspections should be conducted regularly, especially in colder climates where ice could damage panels. Cleaning may also be required to maintain efficiency, but most solar roofing is designed to last for an average of 25 years.

Questions to ask yourself before installing a solar energy system:

• What type of installation would be best suited to my building/property?
• What size of system can my roof support?
• How much direct sunlight hits my roof daily?
• What are my energy requirements?
• How much do I spend annually on electricity?
• How old is my roof, and will a solar electric system add value to my home or business?
• What are the local, state, and federal incentives available?
• Does my local energy supplier offer rebates for solar systems?

How Can Empire Help Me?

Hiring a professional to assess your building and property for optimal efficiency is very important.

When performing an installation, support infrastructure and converters need to be installed to safely harness light and transform it into energy that can be used in your business or home.

Panel angle, placement, the building's architectural design, and shade can all impact a solar electric system's efficiency. Empire Renewable Energy offers a free assessment to determine what type of installation is best suited for your power needs.

For 65 years, Empire has offered superior quality and has served industries across Arizona including education, warehousing, retail, recreation, healthcare, food service and manufacturing.

When you contact Empire for a site assessment, a qualified engineer will determine the specific, and most optimal, system available to help you reduce your energy expenses. The assessment will determine the size of photovoltaic system needed, where it should be placed, and what angle the panels will be titled to capture the maximum amount of sunlight.

In addition, Empire's engineers will determine what type of system and installations options will be needed, how much you'll save, and how quickly you'll see a return on your initial investment. This will include an estimate for installation costs, available financial incentives, and first year production estimates along with annual savings projections.

Contact Empire Renewable Energy to get started today.

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