The best solar panels are those with high efficiency and long warranty because they generate the most savings. All factors being equal—location, available space (roof or another dedicated area), shading, climate and natural degradation of the panels—monocrystalline panels are the best panels for home use. You should look for monocrystalline panels from solar energy companies that can prove high-efficiency rates and offer a comprehensive warranty on product and workmanship. This will generate the most savings and incur limited maintenance costs.
The best solar panel companies
Top-rated solar panel companies should offer a high-efficiency rate and comprehensive warranty options. It is also important to evaluate the quality of materials and labor and the reputation of the manufacturer or provider. The durability and ability of solar panels to produce electricity depend on several factors like the quality of materials built into them, weather and location of the panels in your home for optimum sunlight intake. Solar panels degrade through constant exposure to the elements. Your manufacturer should be able to guarantee that their solar panels are able to withstand the conditions in your area.
For over 20 years, SunLux has focused on helping consumers save money by pinpointing their properties’ exact energy needs. SunLux handles everything from paperwork and site evaluation to the installation of, turning on and maintaining your solar system. Locations in California, Texas, Nevada and Arizona. Offers options to purchase, finance, pre-pay or lease for $0 down. Systems come with a 25-year comprehensive warranty that includes coverage for the physical components of the solar system, replacement parts, repairs and maintenance.
Vivint Solar provides solar panels and a product line of solar batteries, powerful chargers and smart home apps to customers in 22 states. Residential solar panel finance options include purchase, solar loan, solar power purchase agreement (PPA) and solar lease for as little as $0 down. Systems include maintenance, monitoring and a 25-year panel warranty. Vivint has partnered with LG Chem and provides batteries with an energy capacity of 9.8 kWh and warranty of 10 years. This is a diversified product that charges an electric vehicle six times faster than a conventional outlet. Vivint was awarded the 2016 BIG Innovation award in 2016.
SunPower designs and manufactures residential, portable and commercial solar panels. They specialize in attractive high-efficiency solar cells, like SunPower Signature with anti-reflective black roof panels, and their flexible solar panels are lightweight and portable enough for travel. Payment options include solar leasing, a solar loan, or cash purchases, and SunPower handles permitting paperwork, tax incentive applications, testing, monitoring and maintenance. Panels can last up to 40 years. SunPower’s EnergyLink app lets you sync your panels to your phone, so you can track your efficiency in real time.
SunRun offers plans to purchase, lease or loan a residential solar panel system. They use BrightPath satellite imaging software to customize solar energy systems for your particular home, which increases efficiency and saves customers money. SunRun monitors all systems daily, including solar production. If something goes wrong, the monitoring team is alerted and immediately sends a technician to fix it. Over the last decade, SunRun has serviced more than 100,000 customers in 22 states, Washington, D.C., and Puerto Rico. SunRun offers a lifetime warranty on their products.
Crystalline solar energy panels make up the majority of solar panels used for residential solar power. The purity of the crystalline silicon determines how efficient a solar panel is. Polycrystalline solar panels are a popular option for homes but tend to have a lower efficiency rate than monocrystalline solar panels. Thin-film panels are best for commercial buildings or satellites, and concentrated photovoltaic cell panels are only used on satellites and in research labs.
Monocrystalline silicon solar panels are made from melted pure silicon formed into bars and cut into wafers. The most efficient solar panels on the market, these are easily recognized by their uniform dark color and rounded edges. They produce the highest power outputs and require the least amount of space when compared with other panels (most around 15–20 percent efficiency rating). They have the longest lifespan of any panel on the market. Most companies warrant them for around 25 years.
You will need to cover a larger surface area with polycrystalline panels to get the same amount of power as you would from a monocrystalline panel system. Sometimes referred to as “multi-crystalline,” polycrystalline solar energy panels cost less than monocrystalline panels because the process to make them is simpler and less expensive. Polycrystalline solar panels are made from fragments of silicon melted together to form the wafers. With the many crystals in each cell, there is less freedom for the electrons to move around. This results in a lower efficiency rate of about 13–16 percent. Compared to monocrystalline solar panels, polycrystalline panels have a more speckled look and lighter color.
Most commonly associated with amorphous systems, thin-film solar energy panels are made by layering thin solar cells on materials such as glass, metal or plastic. They are cheaper to manufacture than crystalline-based panels, so they’re easy to mass-produce. These are flexible, easier to install and are less affected by high temperatures. Since thin-film panels require a lot of space, they’re not ideal for residential use. They also degrade faster than crystalline panels. High temperatures and shading don’t affect them as much as other panels, so they’re better for wide open spaces like farms and fields.
Concentrated PV cell
These panels contain a concentrated amount of photovoltaic material, making them the most efficient type of solar panel with a 41 percent efficiency rate. They are extremely expensive and are only used in satellites and research labs, not on residential solar panels.
How efficient are solar panels?
The efficiency of a solar panel simply describes how well it turns sunlight into usable electricity. These days the average efficiency of a solar panel is about 18.7 percent. This means that, under ideal conditions, 18.7 percent of sun waves that hit the panels will be converted into usable electricity. Efficiency levels affect how much solar panels cost.
The energy that a panel can produce will vary by its location and its available sunlight, but, in general, most home solar panels have power output ratings ranging from 250 to 400 watts, with an average of about 320. The number of panels you need will depend on the efficiency of the panel plus the electricity your home requires.
Monocrystalline solar panels tend to be more efficient than polycrystalline solar panels, and both monocrystalline and polycrystalline solar panels tend to perform better than thin-film solar panels. There are many different solar panels on the market—each with their own benefits and disadvantages. Solar panels used for the rooftop solar market are less varied, but there are still considerable differences between each brand.
What is a solar panel efficiency calculation?
A solar panel efficiency calculation is simply the conversion rate used to measure how much of the sun’s rays a panel can convert into usable energy. Specifically, it is the portion of energy from sunlight that can be converted into electricity. Manufacturers figure this out by multiplyingthe incident radiation flux, or the amount of available sunlight in your area based on standard testing conditions (STC) t by the area of your panel in square meters. The panel’s maximum wattage is divided by this number and then multiplied by 100 percent to calculate solar panel efficiency.
What affects solar panel efficiency?
The efficiency of a solar panel is determined by a variety of factors. The average home can easily be powered by a solar panel with 14–18 percent efficiency, so a higher efficiency rating is not the only important qualification. Outside of manufactured factors, like efficiency, power ratings and degradation rates, there are a variety of external factors that can affect the performance of your solar panels:
Some photovoltaic (PV) systems are considered tracking systems and will reposition themselves for maximum performance based on the sun’s position. If your system is a non-tracking system, plan to adjust your panels twice a year: once in the summer months and once during winter. In the summer, adjust your system at a lower angle to catch more sunlight. In the winter, angle your system higher.
Perhaps obviously, shade is not great for a solar system. Because solar cells are connected in a series, even just a little shade on one panel can cease solar production on all other panels. Trim trees to make sure no shade falls on any part of the solar panel.
Like most mechanical equipment, solar panels work best when they are kept cool and dry. Higher temperatures can reduce a solar panel’s production of power by 10–25 percent. Panels should be positioned in areas with significant airflow and natural cooling in order to maintain efficiency rates. Before buying, consider a panel’s temperature coefficient, which describes how effective your panels will produce electricity when your climate is less than ideal for solar panel production.
Although regular maintenance is not needed on grid-tied systems, routine cleaning is recommended in order to remove dust, dirt and other traditional contaminants that can affect efficiency. If your area does not receive rainfall, you can wipe off dust with soapy water or by hiring a cleaning service.
Bottom line: Are solar panels worth it?
Solar panels are worth it both for the long-term utility savings and the environmental impact. When you’re choosing a solar energy company to power your home, look for one that has a high-efficiency rating to maximize the amount of power your solar energy system generates and a good warranty to protect you from future maintenance costs.
As a member of the ConsumerAffairs Research Team, Kathryn Parkman believes everyone deserves easy access to accurate and comprehensive information on products and businesses before they make a purchase, which is why she spends hours researching companies and industries for ConsumerAffairs. She believes conscious consumption is everyone's responsibility and that all content deserves integrity.