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The 3 Different Types of Solar Power Systems Explained

Author: Helen

Feb. 04, 2024

199 0

Tags: Energy

The 3 Different Types of Solar Power Systems Explained

There are three basic types of solar power systems: grid-tie, off-grid, and backup power systems. Here’s a quick summary of the differences between them:

  • Off-grid solar is designed to bring power to remote locations where there is no grid access.

  • Off-grid systems require a battery bank to store the energy your panels produce. They are often paired with a generator to provide backup during long stretches without sunlight.

  • A backup power system connects to the grid, but also includes batteries. Backup power systems (also called “hybrid systems” or "energy storage systems") provide backup power in case the grid goes down.

Each system type requires unique equipment that is compatible with the application, so understanding which one you need is the first step in the process of going solar. 

Let’s take a closer look at the different types of solar power systems and make a comparison between them.

Grid-Tie Solar Power Systems

Grid-tie solar is, by far, the most cost-effective way to go solar. Because batteries are the most expensive component of any solar system, but grid-tie solar owners can skip them completely!

So how do grid-tie solar power systems work?

First, let’s define what we mean by the “grid”. The grid is the utility company’s network of equipment that brings electricity from the power plant to your home or commercial building. If a building is getting electricity from the power company, it is connected to the grid.

Grid-tie solar systems send the energy they generate into the grid, where it is stored for later use. Under a net metering agreement, the system owner receives credit for anything they generate, and they can make use of that energy at any time.

It’s kind of like a bank account: sending energy into the grid is like making a deposit, and using electricity is like withdrawing against your account balance. If you overdraft i.e. use more energy than you produce in a given month, the utility bills you for the difference. No added fees, thankfully.

Advantages of Grid-Tie Solar Power Systems

Grid-tie solar is the best option if you want to offset your electricity bill and save money over the life of your system.

Most grid-tie systems pay for themselves within 5-10 years. With solar panels warrantied for 25 years, grid-tie solar is the only option that reliably turns a profit for the system owner over the life of the panels.

Another advantage is that grid-tie systems can be smaller — you don’t need to generate 100% of your power each month. The grid can supply additional power beyond your production, which is useful when bad weather hampers the output of your panels, for example.

Some people choose to size a grid-tie system for a partial offset of their bill, with plans to expand the system later once their budget allows for it. Design requirements are less demanding than in an off-grid environment, where you are fully responsible for your energy needs.

Disadvantages of Grid-Tie Solar Power Systems

The main disadvantage of grid-tie systems is that they are still vulnerable to power outages.

"But wait," you might say, "if I’m generating power from sunlight, why does it matter if the grid goes down?"

Unfortunately, grid-tie systems are wired into the utility company’s infrastructure. In case of an outage, utility workers need to troubleshoot and fix the problem, and they can’t do that if connected solar systems are still energized and feeding power to the grid. For that reason, grid-tie solar systems are switched off during outages to allow utility workers to safely make repairs.

The solution? A hybrid system that connects to the grid, but draws on a battery bank in case of outages. We’ll cover those at the end of this article, but first...

Off-Grid Solar Power Systems

Off-grid solar is best for delivering power to remote locations where there is no access to a utility line.

Folks who live off the grid are solely responsible for generating their own electricity. This is usually accomplished by building an off-grid solar system that can cover a day’s worth of electricity usage, with a backup generator to supplement production during long stretches of bad weather.

Advantages of Off-Grid Solar Power Systems 

The main draw of off-grid solar is the freedom to live wherever you want. It doesn’t matter if your property is 100 miles from civilization: if you have sunlight, you have a reliable way to generate power.

Although off-grid solar components are more expensive, there can be some hidden financial benefits to living off the grid that can offset those higher costs. Undeveloped plots of land located far off the grid will naturally cost less than a prime grid-tie location. In many cases, the lower land costs do more than enough to offset the higher cost of going solar off the grid.

Disadvantages of Off-Grid Solar Power Systems

Pretty simple, really: the need for a battery bank makes off-grid solar significantly more expensive.

However, it’s often wiser to invest in an off-grid solar system than it is to run a power line to a remote location. While an off-grid system may cost more than a grid-tie system, it is still more frugal than other remote power solutions, like running a new utility line or relying on a gas generator.

One way to keep costs down is to use propane appliances where possible to reduce your demand for electricity. Opting for a propane stove, clothes dryer, wall heater and on-demand water heater means you can get away with a smaller inverter and smaller battery bank.

It also helps to stagger electricity usage — for example, running laundry and the dishwasher at different times — to reduce your peak power consumption and relieve some of the costs of energy storage.

Backup Solar Power Systems

If you live on the grid, but you want protection from power outages, your best bet is a battery backup system.

Backup power systems connect to the grid, and function like a normal grid-tie system on a day-to-day basis. However, they also feature a backup battery bank that takes over in case of outages.

When grid power goes out, your inverter automatically disconnects from the grid and draws on energy stored in your battery bank, which will keep your appliances running when the grid goes down.

Battery backup systems have been gaining popularity recently, especially in light of news stories covering grid failures in Texas and wildfires interrupting service in California. They are also favored in climates that are vulnerable to fierce storms and natural disasters like hurricanes and tornadoes. The backup battery bank offers peace of mind to shield the owner from blackouts.

Lastly, battery backup is valuable if you have appliances which require uninterrupted power. If you are running a well pump, for example, service interruptions can be a massive headache. Adding backup power to your grid-tie system will keep these critical appliances running during a blackout.

Can I start with grid-tie solar and add battery backup later?

Yes, but it’s much easier to do if you plan for expansion in advance. Traditional grid-tie inverters like the SMA Sunny Boy aren’t equipped to handle a battery bank connection. Those can be paired with the SMA Sunny Island inverters to upgrade a hybrid battery based system, but you'll spend more coupling a second inverter to your system.

Hence, iIf you think that you may want to add battery backup to your system down the line, we recommend a solution like the Sol Ark series, a string inverter which is engineered to handle all three applications: grid tie, off grid, and battery backup.

There's also the Enphase Ensemble, a “grid-agnostic” micro-inverter system that is designed to seamlessly swap between grid power and backup power.

You’ll be able to start with Enphase IQ micro-inverters for grid-tie use, with the option to add the Encharge storage system later without any compatibility issues.

Watch this 5-minute video from Enphase to see how it works.

We may be compensated if you purchase through links on our website. Our Reviews Team is committed to delivering honest, objective, and independent reviews on home products and services.

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Types of Solar Panels

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By Tamara Jude Reviewed By Sarah Wilder

Choosing the right solar panels can feel overwhelming, especially if you are new to this technology. Solar panels are a big investment, and your choice will affect not only the aesthetics of your home but also the power and financial savings provided by your new system.

Our team has spent more than 300 hours researching the solar industry. In this guide, we’ll cut through the jargon to explain how different types of solar panels work. We’ll cover variations in design, materials, efficiency ratings, and more so that you can make an informed, confident decision for your home.

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Solar Panel Basics

Committing to going solar can be easy, but navigating the installation process may feel overwhelming. Doing some research can help you better understand solar technology and decide what system to install.

Solar panels are made up of dozens of photovoltaic cells (also called PV cells) that absorb the sun’s energy and convert it into direct current (DC) electricity. Most home solar systems include an inverter, which changes the DC electricity to alternating current (AC) electricity—the kind needed to power your home. Solar batteries can store unused energy for use at night or during an outage.

Though there are many brands and styles of solar panels, there are only three main types: monocrystalline, polycrystalline, and thin-film. Monocrystalline and polycrystalline panels are used for residential installations, while thin-film panels are more common for small solar projects, such as powering an RV or shed.

Monocrystalline Solar Panels

Monocrystalline solar panels—or mono panels—are made from a single silicon crystal. These are the most common type of solar panels for residential systems because they’re the most efficient solar panels and better suited for roofs with limited space.

There are two kinds of monocrystalline panels:

  • Passivated emitter and rear contact (PERC) panels: PERC panels are most commonly used for rooftop installations. They have an extra conductive layer on the backside of their PV cells to increase energy absorption. 
  • Bifacial panels: Bifacial panels can absorb light on both faces and at a higher rate than PERC panels. They are typically reserved for ground-mounted systems that leave both sides of the panels exposed. Bifacial panels are also used on awnings, canopies, and highly reflective white commercial roofs.

Monocrystalline Solar Panel Design

Monocrystalline panels are mostly solid black but have some white space throughout. The black design makes them less noticeable on a rooftop.

Monocrystalline Solar Panel Materials

Monocrystalline solar cells are manufactured using the Czochralski method, in which a seed crystal of silicon is placed into a molten vat of pure silicon at a high temperature. That creates a single silicon crystal, or ingot, which is then divided into thinner wafers. Those wafers make up the solar panels.

Polycrystalline Solar Panels

Polycrystalline panels are made using earlier solar technology, so they’re more affordable than the newer monocrystalline variety. However, because the technology is older, polycrystalline panels are less efficient than their modern counterpart.

Polycrystalline Solar Panel Design

Polycrystalline panels have a blue hue that’s somewhat marbled in appearance, so you may see some variation in color and consistency among panels. Homeowners who don’t want to distract from their curb appeal should opt for monocrystalline over polycrystalline panels.

Polycrystalline Solar Panel Materials

Polycrystalline panels use silicon solar cells, the same as monocrystalline panels. The difference lies in the cooling process for polycrystalline panels, which creates multiple crystals rather than just one.

Thin-Film Solar Panels

Thin-film solar cells are less efficient than monocrystalline and polycrystalline varieties. As a result, they are more often used in large industrial solar installations in which space is not a constraint. Thin-film panels can also be a good option for small solar projects, such as powering a boat, and small commercial buildings with thin metal roofs, such as a warehouse.

Thin-Film Solar Panel Design

Thin-film panels have the sleekest appearance among the three panel types. They’re completely black, flat, and flexible in shape and size. They blend in easily on roofs, and they don’t require the scaffolding that monocrystalline and polycrystalline panels often do.

However, thin-film panels are not very efficient. You’d need many more—perhaps even enough to cover your entire rooftop—to generate enough power for a home. That means a higher overall cost and more opportunities for panel issues, failures, and degradation over time Because of all this, thin-film panels arealmost never used for residential installations.

Thin-Film Solar Panel Materials

Thin-film panels are created by placing a thin layer of a photovoltaic substance, such as copper indium gallium selenide (CIGS) or cadmium telluride (CdTe), onto a solid surface, often glass. The photovoltaic substance used in the manufacturing process determines the properties of the final product, with amorphous silicon (a-Si) panels being the most flexible.

Compare the Major Types of Solar Panels

Type of Solar Panel

Pros

Cons

Monocrystalline

  • Lasts more than 25 years

  • Made of the highest-grade silicon

  • Requires the least amount of roof space

  • More expensive than the other two panel types

  • Can be slightly less efficient during cold weather

  • Wastes material during production process

Polycrystalline

  • Lasts more than 25 years

  • Is more affordable than monocrystalline panels

  • Produces less waste during the manufacturing process

  • More easily affected by high temperatures

  • Less efficient than monocrystalline panels

  • Requires more roof space

Thin-film

  • Can withstand high temperatures

  • Is the least expensive panel option

  • Weighs less than monocrystalline and polycrystalline panels

  • Is the least efficient

  • Requires the most space

  • Isn’t sufficient for residential rooftop installations

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How Solar Panels Work

If you’re looking for more information about how solar panels work, the video below describes the process of how solar panels convert sunlight into electricity to power your home.

” src=https://www.youtube.com/embed/EX2vB472PJA””” title=”Understanding Solar Power | Ask This Old House” frameborder=”0″ allow=”accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture” allowfullscreen>

Solar Panel Costs

When we surveyed 1,000 homeowners in August 2022, about one-fifth ranked affordability as their No. 1 priority when shopping for solar panels. So how much do the different types of solar panels cost?

Monocrystalline panels are more costly to produce because they use a single silicon crystal, whereas polycrystalline panels can be made using using leftover crystal fragments. Since production costs are lower and the manufacturing process is simpler, polycrystalline panels are much less expensive than monocrystalline panels. The cheapest type of solar panel is thin-film because of their ultra-light and thin construction.

Here’s the average price per watt for each panel type, which can give you an idea of how much solar panels will cost you. Note that you’ll need more polycrystalline panels than monocrystalline panels to power your home, and that thin-film panels should be reserved for nonresidential projects.

Average Cost Per Watt*

  • Thin-film: $0.70–$1
  • Polycrystalline: $0.90–$1

  • Monocrystalline: $1–$1.50

*Prices sourced from contractor estimates used by Angi, as updated in December 2023.

Solar Panel Efficiency

The more electricity a solar panel can generate, the higher its efficiency rating. High-efficiency panels can generate more electricity while taking up less space, meaning you’ll need fewer panels for your home solar system. That’s why 35% of homeowners in our survey ranked efficiency as their No. 1 priority when shopping for solar panels.

Changes in sunlight throughout the day can impact your panels’ efficiency, since overcast skies will obviously reduce the amount of solar energy panels can absorb. High temperatures can also negatively affect energy efficiency. Panels build up heat throughout the day, lowering the power output by up to 30% during hot summer days.

Both monocrystalline and polycrystalline panels are suitable for most locations that receive an average amount of sunlight and have seasonal temperature fluctuations. Thin-film panels have a lower temperature coefficient than the other two panel types, meaning they lose less power as the temperature rises. This makes thin-film panels a good option for hotter climates or areas that get more annual sunlight.

While temperature changes affect all types of panels, those with high efficiency ratings account for these fluctuations and compensate for them in terms of overall power output.

Below is a breakdown of efficiency ratings and power capacity for each solar panel type.

Monocrystalline Panels

  • Efficiency: Over 20%
  • Power capacity: 300 watts and up

Polycrystalline Panels

  • Efficiency: 15%–17%
  • Power capacity: 240–300 watts

Thin-Film Panels

  • Efficiency: 6%–15%
  • Power capacity: No standard measure, since thin-film panels aren’t uniform in size, but generally less output than crystalline panels

Other Factors To Consider When Selecting a Panel Type

Beyond sunlight exposure and heat, the following factors can impact a solar panel’s performance and longevity.

Hail Rating

Solar panels are tested for hail impacts by dropping small steel spheres from a certain height or firing ice balls directly on panels to simulate hail.

Monocrystalline and polycrystalline panels are made of thicker materials and can therefore withstand hail hitting at speeds of up to 50 miles per hour. Thin-film solar panels are less resistant to hail because they’re more lightweight and flexible.

Hurricane Rating

The U.S. Department of Energy maintains a list of recommended specifications for solar panels in terms of their ability to withstand major storms, such as hurricanes. Panels that meet these specifications are designed with a locking or fastening mechanism to help prevent them from becoming windborne. Monocrystalline and polycrystalline panels are heavier and easier to modify with fastening devices than thin-film panels.

Our Conclusion

Monocrystalline solar panels are the best option for residential solar panel systems. Though more expensive than polycrystalline panels, monocrystalline panels perform better and last longer. This means that despite the higher cost, the increased efficiency and power output of mono panels may actually save you more money on electricity bills over time.

Polycrystalline panels are still a practical option for those who want to switch to solar but can’t afford monocrystalline panels. Keep in mind that if you are worried about aesthetics, polycrystalline panels are the most noticeable on your roof.

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We don’t recommend using thin-film panels for your residential solar system due to their low efficiency. However, they may be a good, affordable option if you want to power a shed, workshop, boat, or recreational vehicle.

Most solar panel installation companies will recommend a panel type and brand based on your home’s needs and your budget. Learn more about the solar panel companies we recommend in our guide.

FAQ About Residential Solar Power

How many solar panels are needed to run a house?

Most houses need about 30 solar panels. That estimate is based on an average energy consumption of 1,000 kilowatts per hour with 320-watt panels installed. The exact number of panels you need depends on several factors, including your average monthly energy consumption, your home’s size and available roof space, and your local climate and average sunlight.

Is it possible to run a house completely on solar power?

Yes, you can run a house completely on solar power. However, you’ll need backup generators and solar batteries that store excess energy to go completely off-grid. Off-grid systems are also larger and, thus, significantly more expensive than those tied to the power grid.

How long do monocrystalline solar panels last?

Monocrystalline solar panels can theoretically last 50 years, but they’re typically only covered under warranty for 25–30 years.  All types of solar panels lose about 0.5% of their efficiency per year due to normal wear and tear, so they won’t be as effective in later years as when they were first installed.

What are the main disadvantages to solar energy?

The main disadvantage of solar energy is that solar panels are expensive to install, with an average cost of roughly $20,000. However, solar incentives, rebates, and tax credits can significantly reduce this price, and the annual savings you’ll receive on electricity bills will eventually pay for the system and then some.

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

The 3 Different Types of Solar Power Systems Explained

Types of Solar Panels (2024 Guide)

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