Types of Solar Panels: Solar Panel Options Explained
Solar energy is becoming an increasingly popular alternative to conventional energy sources that contribute to the burning of fossil fuels and the growing climate crisis. Solely dependent on exposure to sunlight, solar power is clean and renewable—forging the way toward a greener future for all. In addition to being one of the most reliable energy sources available, solar power is becoming easier and more cost-effective as it pervades the modern commercial and residential energy market.
With such promising prospects, the Solar Energy Industries Association estimates that by 2024, 2.5% of all U.S. homes will utilize solar panels. If you’re among the burgeoning population of homeowners interested in outfitting their homes with solar power, understanding what to look for while shopping for solar is an essential first step.
In this post, we’ll take a close look at the many different types of residential solar panels, and highlight the pros and cons of each. There are several variables you should consider before diving into your solar panel project, and we’re here to walk you through the most important considerations.
Photovoltaic vs. Solar Thermal Panels: What’s the Difference?
There are two distinct types of solar technologies: photovoltaic (PV) and solar thermal. The foundational principle is the same for these two technologies—both involve converting energy from the sun into electricity. Photovoltaic solar panels directly transform sunlight into electricity whereas solar thermal panels use sunlight to heat a fluid, which is commonly used for hot water and space heating but can also be transformed into electricity in large-scale operations. Let’s dive a little deeper.
Photovoltaic solar panels are a newer, more modern technology compared to thermal, and come in a variety of subtypes we’ll explore later. Photovoltaic solar panels absorb sunlight and convert it into electricity by using silicon semiconductors. Although photovoltaic systems are more complex in their technological infrastructure, they are the more popular option among commercial and residential buyers.
What are the pros and cons of photovoltaic technology?
When you think of traditional solar energy, you think of photovoltaic solar. While this technology is the more omnipresent solar technology to date, there are always advantages and disadvantages to consider before deciding on the perfect fit for your property.
- Can last up to 30 years.
- Produce direct, cost-effective electricity that offers a solution to energy demand spikes, particularly during hot summer months.
- Are low-maintenance due to no mechanically moving parts (unless you have a ground-mounted install that uses trackers, but this isn’t common for residential systems).
- Can cover a large percentage (if not all) of your household’s electricity needs.
- Tend to be the cheaper solar option due to government price offsets made possible with green energy initiatives.
- Have come down significantly in price while improving output efficiency over the past decade.
- Do not freeze in the winter and perform exceptionally during the summertime.
- Upfront investment costs are typically higher than solar thermal installation costs.
- Power can be unpredictable on cloudy and rainy days.
- Require additional equipment (inverters) to convert direct current (DC) into alternating current (AC) to be used in your home.
- For a continuous power supply, solar PV systems need battery backup systems; otherwise, you’ll have to rely on grid-tied power at night.
- Require a relatively large surface area of your rooftop or plenty of level yard space for a ground-mounted array.
- Average efficiency rates range from only 15%-20%, with some panels reaching 23%.
Solar Thermal Technology
Solar thermal technology collects the sun’s energy and uses collectors to heat a liquid or gas (i.e. water, oil, helium, air, etc.). The heated element is contained inside a glass tube or pipe and later transferred to a storage cylinder. Generally speaking, this type of solar technology is best utilized for heating homes and water heaters.
What are the pros and cons of solar thermal technology?
With solar thermal technology, you’ll be able to enjoy a superior energy solution when it comes to maintaining the temperature of your home environment and water. However, it’s important to be wary of the downsides you should expect as a compromise.
- Requires less space than solar PV, and can be integrated into existing systems.
- Thermal panels are highly efficient and can convert 60% to 70% of the sun’s energy into heat.
- Greater return on investment compared to solar electric systems.
- The best solution for space and water heating.
- Higher storage capacity than PV systems (providing you invest in some type of storage tank).
- Can become less effective in winter months when sunlight is weaker.
- Harder to compete against cheap natural gas for home heating.
- Unlike solar PV, where you can sell power back to the grid via net metering, it’s generally not practical to sell excess heat.
- Shorter lifespan than photovoltaic solar panel systems.
- Can be more difficult to find a good supplier for your residence.
The 3 Major Types of PV Solar Panels
On the market today, there are three main types of solar PV panels, and three major types of solar thermal panels used in residential applications.
First, we’ll discuss solar PV or solar electric panels.
Structurally speaking, all PV solar panels look almost similar, yet each configuration has its own distinct advantages and limitations. The type that’s best for your home will depend on a number of factors: your household energy usage, how much power you want to offset, your price range, your available south-facing roof space, and more.
PV: Monocrystalline Solar Panels
Monocrystalline solar panels are constructed from silicon ingots or blocks, which feature a recognizable cylindrical shape. To capitalize on performance and reduce overall costs, four sides are cut out of the cylindrical ingots to create silicon wafers that look perfectly rectangular with zero rounded edges. Monocrystalline solar panels feature a flat uniform color.
Although monocrystalline solar panels are the most expensive option of the three, they offer the highest efficiency ratings. And, because these solar panels yield the most impressive power outputs, they also require the least amount of roof occupancy. However, it is worth noting that if a monocrystalline solar panel becomes covered in dirt, snow, or consistent shade, the entire system can break down.
PV: Polycrystalline Solar Panels
Polycrystalline solar panels feature solar cells that contain multiple crystalline fragments of silicon. These panels are made up of perfectly square wafers that are assembled into rows and columns to form a rectangular panel covered with a glass sheet and a metal frame. Unlike monocrystalline solar cells, polycrystalline solar panels tend to have a blue hue.
One of the most significant advantages of choosing polycrystalline solar panels is the lower overall cost. Though they are not as inexpensive as thin-film solar panels, they are the perfect middle-ground option for those looking for crystalline-based solar panels that are aesthetically pleasing and high-performing.
Next to monocrystalline panels, polycrystalline solar panels have a slightly lower heat tolerance, meaning they are not able to perform at their peak amid high temperatures. Although this is an important distinction to keep in mind, especially if you live in a hot climate, the reduced performance shouldn’t deter your decision, as the difference is minimal.
PV: Thin-film Solar Panels
The fundamental premise of how thin-film solar cells are made is marked by depositing one or more thin layers of photovoltaic material onto a substrate. Thin-film panels are crafted from a variety of materials, including:
- Amorphous silicon (a-Si)
- Cadmium telluride (CdTe)
- Copper indium gallium selenide (CIGS)
Depending on the material and technology, thin-film solar structures have achieved efficiency ratings ranging between 7% to 13% and output modules run at about 9%. According to Energy Informative, future efficiency ratings are projected to rise approximately 10% to 16%.
The most prominent type of thin-film solar panel is manufactured from telluride cadmium (CdTe). Manufacturers apply a layer of CdTe between transparent conducting layers to develop this type of solar panel that ultimately helps collect and absorb sunlight. This kind of thin-film engineering often features a protective glass coating at the rim.
Copper Indium Gallium Selenide panels (CIGS) are another common thin-film technology. CIGS panels have all four components positioned between two conductive material layers (i.e. glass, plastic, aluminum, or steel). With electrodes mounted on the front and back of the substrate to absorb electrical currents, CIGS solar structures offer the most efficiency potential for thin-film solar panels.
Amorphous silicon (a-Si) solar panels use silicon in their composition; however, they are not made up of solid silicon wafers. Instead, they’re composed of non-crystalline silicon that is placed on top of glass, plastic, or metal. These types of panels are best suited for small-scale applications due to their low electrical power output. However, a manufacturing technique called “stacking” can increase efficiency levels if needed.
The 3 Major Types of Solar Thermal Panels
While some similarities exist between PV and thermal panels, they are quite different. Solar thermal “panels” are actually collectors used for heating applications. Typically bulkier, these panels are more efficient than PV panels because heatwaves carry more energy than sunlight – and there are no additional steps to transform the sun’s rays into heat.
Standing off your rooftop a bit more than photovoltaics, solar thermal panels may look like big flat boxes or a series of glass tubes. Here are the three main types:
Thermal: Evacuated Tube Collectors
Among the most popular solar thermal systems are evacuated tube collectors. Boasting efficiency rates of 70 percent, these solar thermal systems are also the most expensive. Evacuated tube collectors are comprised of rows of insulated glass tubes with copper pipes at their core. Water is heated in the collector, and then sent via pipes to your water tank. The tubes may fuse glass-to-glass or glass-to-metal. The all-glass tubes feature the most reliable vacuum, but reduce the amount of light that reaches the inside absorber. The latter option allows more light to reach the absorber and can reduce the chance of moisture corroding in this crucial component.
These thermal collectors are ideal if you live in an area with a lot of snow, as the gaps between tubes allow snow to fall in the gaps without impacting efficiency, since – unlike PV – there is no radiant heat that enables snow to melt.
Thermal: Flat-Plate Collectors
Used since the 50s, solar thermal flat-plate systems have been made up of a dark-colored flat absorber with an insulated cover and a heat-transferring liquid. The liquid contains antifreeze to successfully transport heat from the absorber to the water tank. The larger size of the flat plate increases heat absorption potential, though efficiency levels are around 50% (but can reach 60% with the addition of a reflector). Still, the cheaper price reflects the lower efficiency and these systems can last 25 years or more.
Flat-plate collectors are ideal if you want a cost-effective solar thermal system and you have plenty of roof space since these panels require more surface area than evacuated tube collectors.
Thermal: Thermodynamic Panels
A new development in solar thermal technology, thermodynamic panels acts more like a solar thermal panel and an air source heat pump to surrounding heat. Based on thermodynamic principles, these panels are designed with a refrigerant running through them that absorbs heat and turns it into gas. The gas passes through a compressor, flows through a heat exchanger coil (aka a dynamic block) that’s inside the water cylinder and the heat is transferred into the water. After the gas transfers its heat, it cools down and reverts back to liquid form – and the process starts over.
With this innovative technology, refrigerant gas takes the place of solar collectors and is said to be more efficient than traditional solar thermal panels – especially when there’s no direct sunlight. Therefore, if you live in a cold, snowy or cloudy climate, this system may be the best option for your home. Additionally, the panels don’t need to be mounted on a rooftop; they can be situated in shady areas, on the siding of your home, etc. since they don’t rely on UV rays. Because these panels utilize gas, they are also much lighter than traditional solar panels.
Which type of solar panel is right for me?
When you have finally decided to invest in a residential solar panel system, the next big step is selecting the kind of solar panels that are best for your property and pocketbook.
If your goal is to use solar to help offset your electricity – kitchen appliances, air conditioner, lights, TV, washer and dryer – you’ll want to explore your solar PV options. If you’re looking into solar to heat your water, swimming pool, hot tub or provide space heating, then solar thermal is your best bet. Many people combine the two systems to fully offset their carbon footprint and significantly reduce their energy bills.
With a more well-rounded understanding of the different types of solar panels available, you’re already in a better position to make an informed decision. However, there are four additional considerations to keep at the forefront of your decision-making process:
- Efficiency: Keep an eye out for efficiency percentages—the higher the percentage, the better the panels will perform in converting the sun’s energy into electricity.
- Aesthetic: If you’re concerned about maintaining the overall aesthetic of your home’s exterior, be sure to choose a solar panel that complements your property and is easy on the eyes.
- Longevity: Although most solar panels will come with a warranty ranging from 15 to 25 years, newer models come with lifespans of up to 30 years. It goes without saying that the longer the warranty, the better bang for your buck.
- Temperature Coefficient: If you live in a hot climate, it’s important to consider the temperature coefficient of a solar panel. This tells you how much power the panel will lose when its surface temperature increases by a certain degree.
With these factors in mind, you’ll be in a great place to move forward with your project with the confidence and self-assurance you need. Don’t forget—installing solar panels is one of many PACE eligible improvements that you can finance with Ygrene. Let us help you bust any solar energy myths and guide you on your path toward green energy.