The 7 Most Efficient Solar Panels

Solar panels come with a high up-front cost, so you’ll want to make sure you’re getting the best bang for your buck. One way to do this is by ensuring you’re investing in the most efficient solar panels for your home. The This Old House Reviews Team analyzed the top Tier-1 solar panels available and determined the best solar panels currently on the market to make this process easier.

This guide walks you through what makes some solar panels more efficient than others, provides recommendations, and breaks down other factors to consider when building a high-efficiency solar power system.

• Q Cells: Best Value
• Silfab: Best Warranty
• Canadian Solar: Most DIY Friendly
• Panasonic: Best Panels for Hot Climates
• REC: Best Durability
• SunPower Maxeon: Most Energy-Efficient
• Longi: Best Mid-Tier Option

Beyond the efficiency rate itself, numerous factors affect which panels will be the most efficient for your home. For example, Panasonic panels are a good option if you live in a hot climate because they perform optimally even in extreme temperatures. Alternatively, if you want to install your solar panels yourself, a DIY-friendly provider like Canadian Solar might be the best fit.

Though these providers have lower efficiency rates than a company like SunPower, they fulfill different needs and situations that may influence the overall efficiency of your solar panel system. For a full breakdown of the most efficient solar panels on the market, check out the table below. You can also use our tool to quickly get in touch with three of the best solar installers.

Solar companies use solar efficiency to measure solar panels’ ability to convert sunlight into usable electricity. Efficiency ratings are expressed as a percentage to help you quickly compare the performance of different solar panels. A solar panel’s solar cell composition, roof location, and design affect its overall efficiency.

For example, if a solar panel has a 25% efficiency rate, 25% of the sun’s energy it captures is converted into usable electricity. If you consider the same amount of sunlight over the same duration of time with another panel, you can determine which panel is a better value for your home’s power output. Though you might think you should just opt for panels with the highest efficiency rate available, lower-efficiency solar panels may be better if your home doesn’t require a lot of energy output or if you’re trying to solar-power a smaller structure, such as a pool house.

The efficiency rate depends mainly on the type of solar panel you use. Monocrystalline solar panels are currently the most efficient and cost-effective option for a solar energy system and the type of solar panel companies most commonly offer. However, polycrystalline or thin-film solar panels may be a better fit for your home if you have more roof space or require limited energy for your solar project. We’ve broken down the pros and cons of different types of solar panels below.

Monocrystalline

Pros

✔ Features an average efficiency of 15% to 25%

✔ Has the longest average lifespan of 35+ years

✔ Yields the highest efficiency rates, so it requires the least amount of roof space

Cons

✘ Tends to have a higher up-front cost than other types of solar panels

✘ Sometimes experiences a decrease in efficiency in colder climates

Polycrystalline

Pros

✔ Features an average efficiency of 11% to 17%

✔ Tends to cost less than monocrystalline solar panels

✔ Has an average lifespan of 25 to 35 years

Cons

✘ Has a lower power output than monocrystalline, so it requires more roof space

✘ Is less heat-tolerant than monocrystalline panels

✘ Features a noticeable blue color instead of the low-key black of monocrystalline panels

Thin-Film

Pros

✔ Features an average efficiency of 10% to 20%

✔ Tends to be the least expensive option

✔ Features a high heat tolerance compared to both monocrystalline and polycrystalline solar panels

Cons

✘ Efficiency ratings vary significantly according to the type of material used in the panel

✘ Less durable than other types of panels

✘ Requires the most amount of roof space to perform well

Several other factors impact efficiency beyond the type of solar panel you use. We’ve listed some of the most significant ones to look out for below.

Solar Cell Type

A solar cell is a small electrical device that converts sunlight into electricity through the photovoltaic (PV) effect. Most solar cell technology is made from small components called crystalline silicon (c-Si) wafers. Single crystals are used to create monocrystalline silicon solar panels. Multiple crystals are used for polycrystalline panels. When ordered correctly, solar cells from a single crystal are more efficient than those pieced together from multiple crystals.

Thin-film solar panels use cells made from amorphous silicon (a-Si). The atoms of these cells are randomly arranged rather than being in an ordered crystalline structure. As a result, they’re less efficient.

Wiring

It may seem obvious, but improper wiring can significantly impact the efficiency of your solar panel system. Different solar modules may have slightly different electrical and wiring components. A mismatch during installation can lead to performance loss. The same issue can occur if inverters between solar panels are mismatched. For example, you might buy various monocrystalline panels, but the design of each panel may cause a dip in efficiency if they’re not designed to work together. Therefore, it’s always best to get solar panels and inverters from the same manufacturer.

Backing

Solar panel backing determines how much sunlight is reflected instead of converted to electricity. The less sunlight a panel reflects, the more efficient it is. Many companies add anti-reflective coatings to increase efficiency.

Many environmental factors influence the efficiency of a solar power system. A solar installer will consider these factors when calculating your quote and possible savings. Read about the most significant environmental factors that affect the performance of your system below.

Temperature

As with electronics, high temperatures hurt a panel’s performance. Typically, solar panels have peak efficiency between 59 degrees Fahrenheit and 95 degrees Fahrenheit. The standard test conditions for panels are 77 degrees Fahrenheit. If your solar panels get hotter than 130 degrees Fahrenheit, you may experience a dip in performance.

Shading

Obstructions such as trees, hills, and other buildings may produce shade on parts of your roof at certain times of the day. How much this affects solar panel power output depends on how long and how frequent the shading occurs and the size of the shadow.

Soiling

Soiling refers to the accumulation of debris, such as dust or snow, on the surface of your solar panels. Though small, this debris blocks light from reaching the solar cells inside your panels, causing inefficiency. Soiling can also change the angle at which sunlight hits your panels, causing the light to spread unevenly. Consider how likely your panels are to experience soiling from dust, sand, or snow to determine how often you might need to clean your solar system.

Weather

Weather and climate play a critical role in the performance of your solar energy system. Regions that are overcast and have more rain and storms are less suited for solar power than regions with clear skies and plenty of sunshine. According to the World Population Review, the states with the most sunshine are (in order):

• Arizona
• New Mexico
• Nevada
• Texas
• California
• Colorado
• Oklahoma
• Kansas
• Utah
• Florida

Orientation and Angle

The angle of your rooftop and the direction it faces are crucial to determining how optimized your home is for solar power. A south-facing roof is best for solar panels. West and east-facing rooftops also work well but won’t be as efficient as a south-facing roof. North-facing roofs are often denied for solar panel installation due to their inefficiency.

Additionally, a 30-degree angle is best for year-round solar production. Many solar companies will consider an installation if your roof is anywhere between 15 to 40 degrees, but 30 degrees offers peak performance.

Though you can receive clean energy from solar panels that run with low efficiency, building a solar energy system that operates at a higher efficiency leads to a better return on your investment. Below are a couple of significant reasons you should consider optimizing your solar power system for peak performance.

Faster Payback

The more energy your solar panels generate, the more savings you receive. Solar panels pay for themselves within six to 10 years on average. However, if your panels operate at peak efficiency, you may be able to close that gap faster.

Space Efficiency and Lower Impact of Project

The solar panel installation process also affects your overall efficiency and cost. The more efficient your panels are, the less of them you’ll need to reach your targeted power output. Fewer panels also mean less crowding and more space on your roof. So while monocrystalline panels are more expensive, their higher efficiency rate means you can cut down on the costs of installation labor and materials compared to buying cheaper polycrystalline solar panels that are less efficient.

Various factors influence how much you will pay for solar panels. According to the Center for Sustainable Energy, the average cost for solar panel installation is currently around $3 to $5 per watt. The installation of an average 5-kilowatt (kW) residential system costs around $15,000 to $25,000 before tax incentives. Read on to learn about other factors that can impact the cost of your solar panel system.

• Household electrical demand: The amount of electricity your household uses every month determines how many solar panels you need. Homes with predominantly gas appliances will use less than those using primarily electric appliances.
• Type of solar panel: Monocrystalline panels tend to cost more than polycrystalline panels because they’re more efficient. You’ll need the higher efficiency option if you have limited roof space.
• Size of the panel: A large solar power system is more expensive because it requires more labor and equipment. However, despite the higher up-front cost, large solar power systems lead to more significant savings over time.
• Solar panel installation cost: The price of installation differs from place to place, which can impact the overall cost. Different solar providers and installers charge varying amounts for their labor. You’ll be provided with more details about the cost when you reach out to a top solar company for a quote.
• Tax incentives: The federal solar tax credit is known as ITC. The federal tax credit value is set at 30% until 2032. However, this value will decrease to 26% in 2033. Additional solar tax incentives vary according to state. To determine what incentives you might qualify for, we encourage you to utilize the Database of State Incentives for Renewables & Efficiency.
• Purchasing options: Customers can often choose between paying up-front or using solar leases or loans. Paying for your system up-front is the most cost-effective option because you receive access to tax incentives and avoid additional expenses from interest rates. Solar loans are also great because you still receive access to tax incentives. A solar lease is appealing because there’s little to no up-front cost. However, you can’t take advantage of any tax incentives.

Before you get a quote on your efficient solar panels, you should understand what common considerations you and your installer will make when picking the right panels for you home, such as number of panels and location.

The video below breaks down those considerations to help prepare you for your quote:

Though it’s essential to consider solar panel efficiency when purchasing solar panels, it’s not the be-all and end-all. Various other factors determine which solar panel is best for your home, including size, efficiency, color, smart-home integration, and more.

We suggest you take your time to consider which solar panel best fits your primary concerns and needs. We also recommend obtaining at least three quotes from three solar installers to compare panel options, services offered, and which solar panel manufacturers they use. Use our tool below to get started quickly.

Our Rating Methodology

The This Old House Reviews Team is committed to providing comprehensive and unbiased reviews to our readers. After over a thousand hours of research on solar companies, interviews with experts, and common customer needs, we’ve created a detailed rating system for solar providers based on six factors:

• Solar equipment, installation, and services (25%)
• Warranty and performance guarantees (25%)
• Brand reputation and certifications (15%)
• Financing options (15%)
• Experience (10%)
• Availability (10%)

Total scores are divided by 20 for a final 5-point rating scale.

To share feedback or ask a question about this article, send a note to our Reviews team at reviews@thisoldhousereviews.com.