Bi facial solar. Monofacial vs Bifacial Solar Panels

# Bi facial solar. Monofacial vs Bifacial Solar Panels

## An Introduction to Bifacial Solar Panels

Bifacial solar panels are a relatively new technology that has increased in popularity over the past few years. These double-sided panels trade increased efficiency for a slightly more difficult installation process.

Standard non-bifacial solar panels are primarily composed of three layers. On top, a layer of transparent glass protects the solar panels and allows the sunlight to pass through. Below that, a layer of silicon converts this solar energy into power. Below the silicon sits an aluminum frame that gives the panel strength and rigidity. Bifacial panels differ from these standard panels in one important way. Instead of a bottom frame consisting of aluminum, there is another layer of glass that allows for the reabsorption of reflected light from the ground.

You can think of bifacial panels almost like an ice cream sandwich. The cookies on top and bottom are the glass, and the ice cream in the center is the silicon that transforms incoming solar power into electrical power.

There are several ways that these bifacial solar panels can be set up. Typically, they are arranged so that one side faces the sun and the other gathers reflected light from the ground.

## How to Maximize the Advantages of Bifacial Solar Panels

Bifacial solar panels are similar in shape to standard solar panels; they’re flat. This means that only one side is able to gather energy directly from the sun at any given time.

If you set up your solar panels at an angle over reflective surfaces, you can see up to 10% extra solar power generation. The light reflected off the ground determines the amount of extra power that two-sided panels generate. One way we can measure the amount of reflected light is by looking into the albedo of various substances.

### What is Albedo?

Scientists use the term albedo to rate how much light is reflected off of a given surface. If you’ve ever been skiing, you know that fresh snow reflects light very effectively. Snow has an albedo of.9, meaning, up to 90% of all incoming sunlight is reflected. On the other hand, fresh black asphalt has an albedo of around.05.

Therefore, when installing bifacial solar panels, check the ground underneath them. Installing bifacial solar panels over asphalt will result in almost no added efficiency, while installation over bright high-albedo surfaces, like white sand, will result in higher efficiency.

Rule of thumb: brightly colored or white substances typically have a higher albedo.

## Tips for Installation of Bifacial Solar Panels

If you have limited space for your panels and a high need for energy, you should go with bifacial solar panels. Here are some tips for the installation.

Most of the damage done to a solar panel over the course of its lifespan occurs during installation and maintenance. At SanTan Solar, we firmly believe in the old adage: “Measure Twice, Cut Once.” Before you climb up on the roof of your house, make a detailed plan for where you’ll be placing your frame, where you’ll be running your wires, and what you’ll be using as a highly reflective material to maximize reflected light.

A part of this planning step involves deciding how you’ll be incorporating high-albedo materials below your solar panels. What should you use for your reflective material?

### Reflective Materials

While snow and white sand both excel in their reflective properties, neither would last long on a roof during normal weather conditions. We recommend two main solutions. The first is painting the material beneath your panels with white paint. This could mean your roof tiles, painting asphalt, or whatever other material that may sit beneath your panels.

The other solution is white rocks. You can find cheap bags of high-albedo rocks at Lowe’s or online. Remember, anything white typically has a higher albedo than darker colored objects. The lighter you can get the ground under your panels, the better they’ll perform.

### Angle of Installation

Even if the materials under your panels are highly reflective, you must install them at an angle or no light will reflect off the ground. Angling the panels will ensure both sides gather the light.

## What Are Bifacial Solar Panels?

A bifacial solar panel is designed with exposed solar cells on both sides of the panel. This allows sunlight to reach both the front and back of the solar cells for maximum solar energy harnessing.

This varies from traditional solar panels which are designed only to capture sunlight through their front side. In most cases, monofacial solar panels come with a frame and a backsheet made of polymers used to protect and isolate the electrical circuitry of the solar panel.

Bifacial solar panels unique transparent design of photovoltaic (PV) panels can also absorb reflected sunlight off of the ground, water or other materials. This makes bifacial solar modules an excellent choice for ground-mounted systems, carports and more.

## What do Bifacial Solar Panels Look Like?

The panels are often frameless, with no metal gridlines impacting their structural integrity and aesthetic value. With this design, the solar panels have a noticeably thin profile and can be seamlessly added to canopies, carports, pergolas and sun-breakers.

Also, because they are designed to be raised from the ground on a racking system, there is less of a chance of the cells overheating.

Solar PV panels are made up of one of two types of crystalline cells: monocrystalline or polycrystalline. Most bifacial solar panels use monocrystalline cells, leading to maximum efficiency and therefore a higher price.

### SunPower

SunPower designs and installs industry-leading residential solar and storage solutions across all 50 states. With a storied history of innovation dating back to 1985, no other company on this list can match SunPower’s experience and expertise.

SunPower earns its position as the top national installer on our list for a handful of reasons: It installs the most efficient solar technology on the residential market, offers the most expansive service area and backs its installations with a warranty well above the industry standard. All the while, SunPower pioneers sustainability efforts within the industry.

If that weren’t enough, SunPower systems come packaged with products all manufactured in-house by its sister company, Maxeon. This means that your panels, solar cells, inverters, battery and EV chargers are designed to work together and are all covered under the same warranty.

SunPower’s biggest downside? Its high-efficiency panels are considerably more expensive than most of its competitors’ products. However, its powerful panels are workhorses that make up for the initial cost with more backend production (think about this like spending more money for a car that gets more miles per gallon).

### Blue Raven Solar

We like Blue Raven Solar because it understands that, for most homeowners, the cost of solar presents the biggest barrier to entry.

For that reason, Blue Raven Solar developed an innovative solar financing plan that offers in-house, flexible, zero-money-down options. The results speak for themselves, as Blue Raven Solar is now one of the fastest-growing solar companies in the nation and was recently acquired by SunPower. Its BluePower Plus plan (exclusive to Blue Raven) mimics the flexible structure of a lease while still providing the greatest benefits of owning your system.

Eligible homeowners enjoy 18 months of solar power before having to pay their first bill. When coupled with the federal solar investment tax credit (ITC), the initial energy savings can offset more than a third of the overall cost of a system before requiring a dollar down.

In contrast, other installers can only offer similar financing through solar leases, PPAs or third-party providers (such as Mosaic or Sunlight). Third-party loan providers can complicate the process, while opting for a loan or PPA will disqualify you from some of solar’s biggest benefits (additional property value, federal solar tax credit and local solar incentives).

## How Do Bifacial Solar Panels Work?

Bifacial solar panels work like a typical solar panel in the sense that sunlight is absorbed by the solar cells and then converted into energy. But unlike monofacial panels, bifacial panels have two translucent sides to absorb sunlight on both faces of the panel. This increases the total energy gained by the panel relative to the space it takes up.

If excess sunlight collides with a reflective surface below the panel, it can bounce back and be absorbed by the rear side of the solar module. With both sides of the solar panel generating power, bifacial solar energy can produce more solar energy than monofacial modules when the system is angled toward a highly reflective surface.

To utilize this technology, bifacial panels need to be installed with space behind them. This makes them impractical for most home solar panel installations where panels are installed directly on a rooftop.

The places where bifacial panels perform the best are near:

Bifacial solar panels are even productive on cloudy days, as their design is centered around reflected light.

## Higher energy yield with bifacial solar panels

We design and develop bifacial modules that meet specific requirements, for example by reducing the amount of silver in the panels to optimise costs and performance under reduced light conditions. We are also working on the application of light-capturing materials to improve light coupling in and on modules. In addition, we are looking for solutions for cell and bypass diode positioning to take into account increased shading due to robust frames, for example in the case of noise barriers.

We have also developed a new bifacial solar panel with a white layer around the cells. These white, bifacial solar panels generate 5% more energy compared to partially transparent bifacial panels with only transparent glass and plastic layers around the cells. The yield of the white bifacial panels compared to single-sided panels depends on the location of the installation and can be about 10 to 20% higher.

## Predicting energy yield with BIGEYE

We developed BIGEYE in order to make an accurate prediction of the energy yield of a PV system with bifacial modules for all parties. This is a very advanced, and as far as we know the most complete, simulation model for a PV system. With BIGEYE, we can simulate the electricity output of PV systems with any configuration and at any location. With meteorological and environmental data, we calculate the electricity production per hour, day, month or year.

For PV installers, project developers, and system owners, it is very valuable to have a precise energy generation profile. This allows them to provide optimal connections to the local, national, and global electricity grid. In addition, BIGEYE helps to design PV systems in such a way that power generation better matches daily needs. For example, by increasing energy generation in the morning or afternoon.

## Knowledge and technology

Our experts are working on various new cell concepts with the aim of increasing efficiency and simultaneously reducing manufacturing costs. One of the bifacial cell concepts we have developed is an industrial version of the so-called TOPCon solar cell. This cell has special intermediate layers on the back, consisting of a very thin oxide and polysilicon layer. This structure counteracts the losses on the surface. We developed this cell concept in collaboration with Tempress Systems, among others, under a TKI Urban Energy grant project and in several commercial projects. This technology has now been embraced by the industry and cell efficiencies of over 23% are being achieved in production.

In one of the latest bifacial cell concepts, very thin metal oxides are incorporated in the interface layers. These interface layers can be applied on both sides and have the same quality as those in the TOPCon cell, but they are much more transparent, allowing sunlight to enter the solar cell optimally. The bifacial performance of the solar cell can therefore be improved considerably, while production is potentially simpler and therefore cheaper. This concept is still under development in collaboration with Solmates, Levitech, Eindhoven University of Technology, and Delft University of Technology. We expect that with this technology, inexpensive solar cells can be produced with more than 25% efficiency.

### Benefits and Limitations of a Bifacial Solar Panel

An eager mind always wants more specifics before making a decision. Hence, we’ve curated this section on the benefits and limitations of bifacial PV panels.

• – They have better efficiency
• – They perform better when the weather is cloudy or there’s snow
• – They are apt sources to trap sunlight and produce clean electricity

### Limitations of bifacial panels:

• – They’re slightly expensive
• – They perform to their best caliper when trackers are installed. But the inclusion of solar trackers increases the maintenance cost.

The cost of bifacial solar panels used to be very high. Hence, they weren’t considered that great a choice for residential sector earlier. However, with latest advancements, the have gone down. Therefore, bifacial solar panels have entered the residential sector too.

### Conclusion:

A bifacial solar panel has an efficiency of up to 22% but it’s also about ₹1/watt costlier than monofacial solar panels. However, with advancement in technology, bifacial solar panels are becoming cheaper; hence, more popular in the residential sector.

Are bifacial solar panels better?

It entirely depends on the context and use case.

They’re better in terms of efficiency and output. Also, the surface they’re being installed on matters.

Are bifacial solar panels more expensive?

Yes, a bifacial solar panel is more expensive. It is approximately ₹1/watt costlier than monofacial solar panels.

What are the disadvantages of a bifacial solar panel?

Their cost is their biggest limitation. If solar trackers are installed, it only increases the maintenance cost and the break-even period. However, there’s usually no need to install solar trackers for residential installation. Solar trackers are usually required for commercial purposes.