Usually the solar cells we see are single-sided solar cells, which can well accept direct sunlight and convert light energy into electricity. However, they can't do anything about some reflected sunlight. To take advantage of the reflected sunlight, double-sided solar panels must be used.

Bifacial solar panels can generate more electricity than conventional solar panels, but only if they have room for reflected light to reach the back of the panel. This means that they work best in a specific location, rather than placing them right on the roof. If you're mounting your solar panels on a pergola or ground mounted system, a double-sided panel might make perfect sense.

How do double-sided panels work?

A new thermodynamic formula shows that double-sided solar panels generate an average of 15 to 20 percent more solar energy than today's single-sided solar panels, taking into account different terrains such as grass, sand, concrete and dirt. This formula, developed by two physicists at Purdue University, can calculate in minutes the maximum amount of electrical energy a bifacial solar cell can generate in a variety of environments (as defined by thermodynamic limits).

It is understood that there is also enough light reflection on the back of the panel to generate electricity. To get the most out of double-sided panels, there are several key factors to consider.

First, the more reflective the environment around the panels, the more energy they generate. Light-colored environments will reflect more light and improve performance. "We found that when grass turns brown, it becomes more reflective and snow is very reflective," one researcher said in a report from the National Renewable Energy Laboratory. Consultancy Wood Mackenzie It also means that desert countries like Australia, which have a lot of reflective sand, can make better use of double-sided panels than their neighbors, the report said.

Second, there needs to be room for the reflected light to reach the back of the panel. This means that the double-sided panels don't make sense on the roof, as they are almost clinging to the roof. They're best used in large commercial installations, where they're suspended from poles with plenty of room for light to bounce off the back.

Double-sided panels outperformed traditional single-sided panels throughout the year. Under ideal conditions, double-sided panels can generate 27% more energy.

Double-sided panels can be used at home

Bifacial solar PV panels don't cost much more than other solar panels, so if you have the right place, they're an attractive option. Even if there is no benefit to installing them on the roof, in some cases homeowners may still opt for double-sided panels.

Bifacial panels may be a good option if the solar panels are installed on the ground rather than on the roof. This is especially true if you live in a snowy area, or if you can mount it on a more reflective surface like sand.

It may also be beneficial if a double-sided panel is used to build a covering on the exterior area. A pergola or awning with open space below will be far enough from the ground to allow reflected light to reach the back of the panel. Creative people may find other better ways to deploy double-sided panels.

Although not helpful in most residential applications, double-sided panels are another tool that can help you absorb more energy from the sun. Using them in the right circumstances can help you reach your energy goals for a fraction of the extra cost.

What is the role of solar photovoltaic modules?
What are the application fields of solar photovoltaic modules?

Solar photovoltaic modules are the core part of the solar power generation system, and also the most important part of the solar power generation system.

Application fields of solar photovoltaic modules

1. User solar power supply: 

(1) small power supply ranging from 10-100W, used for military and civilian life in remote areas without electricity, such as plateaus, islands, pastoral areas, frontier posts, etc., such as lighting, TV, tape recorders, etc.; 

(2) 3 - 5KW home roof grid-connected power generation system; 

(3) Photovoltaic water pump: solve deep water well drinking and irrigation in areas without electricity.

2. Transportation field: such as beacon lights, traffic/railway signal lights, traffic warning/sign lights, Yuxiang street lights, high-altitude obstruction lights, highway/railway wireless telephone booths, unattended road shift power supply, etc.

3. Communication/communication field: solar unattended microwave relay station, optical cable maintenance station, broadcast/communication/paging power system; rural carrier telephone photovoltaic system, small communication machine, GPS power supply for soldiers, etc.

4. Petroleum, marine, and meteorological fields: cathodic protection solar power systems for oil pipelines and reservoir gates, domestic and emergency power supplies for oil drilling platforms, marine testing equipment, meteorological/hydrological observation equipment, etc.

5. Household lamp power supply: such as garden lamps, street lamps, portable lamps, camping lamps, mountaineering lamps, fishing lamps, black light lamps, rubber tapping lamps, energy-saving lamps, etc.

6. Photovoltaic power station: 10KW-50MW independent photovoltaic power station, wind-solar (firewood) complementary power station, various large parking plant charging stations, etc.

7. Solar buildings: Combining solar power generation with building materials will enable large buildings in the future to achieve self-sufficiency in electricity, which is a major development direction in the future.

8. Other fields include: 

(1) Supporting cars: solar cars/electric cars, battery charging equipment, car air conditioners, ventilation fans, cold drink boxes, etc.; 

(2) Solar hydrogen production plus fuel cell regenerative power generation system; 

(3) Sea water Power supply for desalination equipment; 

(4) Satellites, spacecraft, space solar power plants, etc.

Photovoltaic energy storage power generation main energy storage technology

my country's photovoltaic industry has great potential for development. Do you know what are the main energy storage technologies for photovoltaic energy storage power generation?

Pumped water energy storage: Pump water for energy storage when the power supply of the grid is excessive, release water for power generation when the power supply is insufficient, reduce the impact on the grid caused by the integration of renewable energy power generation into the grid, and keep the power generation of the system in a stable state.

Flywheel energy storage: Flywheel energy storage has the advantages of high power density, long equipment life, clean and environmental protection, strong adaptability, and no need for frequent maintenance. However, flywheel energy storage has low energy density and high installation and maintenance costs. The system is used together.

Compressed air energy storage: When the power consumption is low, the air is compressed and stored by the electric energy and then released during the peak power consumption. The released air is burned and heated to drive the motor to generate electricity.

Battery energy storage: Although lead-acid batteries are cheap, they have a short service life and cause serious environmental pollution; lithium batteries have the advantages of high energy density and long service life, but they are prone to failure or even explosion in short circuit, overcharge and other conditions , has safety hazards; sodium/sulfur batteries have the advantages of large current discharge and long life, but they are easy to cause safety problems when they are overcharged.

Superconducting energy storage: It has the advantages of high energy storage and high charging/discharging efficiency, which can improve power transmission capacity and power quality, but the cost is relatively high.

Supercapacitor energy storage: Supercapacitors store charges on the plates, and their charging and discharging are physical processes, which are mainly suitable for occasions with high power and small capacity.

The inverter not only has the function of DC to AC conversion, but also has the function of maximizing the performance of solar cells and the function of system fault protection. In summary, there are automatic operation and shutdown functions, maximum power tracking control functions, anti-solitary operation functions (for grid-connected systems), automatic voltage adjustment functions (for grid-connected systems), DC detection functions (for grid-connected systems), and DC grounding detection function (for grid-connected systems).

The following briefly introduces the automatic operation and shutdown functions and the maximum power tracking control function:

1. Automatic operation and shutdown function

After sunrise in the morning, the intensity of solar radiation increases gradually, and the output of solar cells also increases accordingly. When the output power required by the inverter is reached, the inverter starts to run automatically. After starting to run, the 10kw 3 phase off grid hybrid solar inverter will monitor the output of the solar cell components all the time, as long as the output power of the solar cell components is greater than the output power required by the inverter, the inverter will continue to run; it will stop until sunset, even on cloudy and rainy days The inverter also works. When the output of the solar cell module becomes smaller and the output of the inverter is close to 0, the inverter will form a standby state.

2. Maximum power tracking control function

The output of the solar cell module varies with the intensity of solar radiation and the temperature of the solar cell module itself. In addition, because the solar cell module has the characteristic that the voltage decreases with the increase of the current, so there is an optimal operating point that can obtain the maximum power. The intensity of solar radiation is changing, and obviously the best working point is also changing. Relative to these changes, the operating point of the solar cell module is always at the maximum power point, and the system always obtains the maximum power output from the solar cell module. This kind of control is maximum power tracking control. The biggest feature of the inverter used in the solar power generation system is that it includes the function of maximum power point tracking.

The characteristics of photovoltaic inverters are:

1. Higher efficiency. Due to the high price of solar cells at present, in order to maximize the use of solar cells and improve system efficiency, it is necessary to try to improve the efficiency of the inverter.

2. High reliability. At present, the photovoltaic power station system is mainly used in remote areas, and many power stations are unattended and maintained. This requires the inverter to have a reasonable circuit structure, strict component selection, and requires the inverter to have various protection functions, such as input DC Polarity reversal protection, AC output short-circuit protection, over-temperature and overload protection, etc.

3. The input voltage has a wide range of adaptation. Since the terminal voltage of the solar cell changes with the load and the intensity of sunlight, especially when the battery ages, the terminal voltage varies greatly. For example, for a 12V battery, the terminal voltage may vary between 10V-16V, which requires The inverter guarantees normal operation within a large DC input voltage range.

PERC solar cell technology is currently at the top with the highest market share of 75% in the solar industry, while heterojunction solar cell technology started to be adopted in 2019 and its market share was only 5.2021% by 2019. TOPCon is almost non-existent in the market, already accounting for 8% of the PV market, but it may start to grow in 2023 as major manufacturers switch from PERC/PERT to TOPCon.

Considering the technical specifications, PERC technology has been left behind by heterojunction and TOPCon solar cell technologies. PERC has an efficiency of 24.5% and a bifacial coefficient of 70%, while TOPCon has an efficiency of 26.1% and a bifacial coefficient of 85%, while a heterojunction has an efficiency of 26.56% and a bifacial coefficient of 92%. Compared with TOPCon, the temperature coefficient of PERC solar cells is worse at 0.3%/ºC, while the temperature coefficient of heterojunction solar cells is even lower than 0.21%/ºC.

Heterojunction solar cells may look promising, but the technology has had major setbacks due to the high cost of producing solar cells and their incompatibility with current technology's production lines. This is where TOPCon solar cells have a head start, because TOPCon solar cells require virtually the same production line as PERC/PERT, and the cost is very similar.

Considering that the technical specifications of HJT and TOPCon solar cells are similar, but considering the setbacks of HJT technology, it is understandable why major manufacturers such as Trina Solar, JinkoSolar, LONGi, etc. choose TOPCon solar cells over HJT .

Photovoltaic glass, also known as "photoelectric glass", is a special glass that presses solar photovoltaic modules, can use solar radiation to generate electricity, and has related current extraction devices and cables. It is composed of glass, solar cells, film, back glass, special metal wires, etc. It is the most novel high-tech glass product for construction.

The main raw materials of photovoltaic glass include quartz sand, soda ash, limestone, dolomite, sodium nitrate, Glauber's salt, sodium pyroantimonate, aluminum hydroxide, etc. Its production process is mainly divided into two major links: original film production and deep processing. The production of the original sheet is to obtain the untreated semi-finished photovoltaic original sheet after five steps of mixing, melting, calendering, annealing and cutting of raw materials, and then further processing. The deep processing process includes two processes of tempering and coating. The original film is edged and then tempered to obtain a tempered sheet, or tempered + coated to obtain a coated sheet for component packaging.

At present, the mainstream product of photovoltaic glass is low-iron toughened patterned glass (also known as toughened suede glass), with a thickness of 3.2mm or 4mm. In the wavelength range of solar cell spectral response (380~1100nm), the light transmittance can Up to 91%, and has a high reflectivity for infrared light greater than 1200nm. It is made by using a special embossing machine to press a special pyramid-shaped pattern on the surface of ultra-white glass.

The main function of photovoltaic glass is to protect the battery from water vapor erosion, block oxygen to prevent oxidation, high and low temperature resistance, good insulation and aging resistance. It is an important part of solar photovoltaic modules and has important values of protecting cells and light transmission.

The advantages and disadvantages of photovoltaic glass are as follows:

advantage:

Photovoltaic glass can use solar radiation to generate electricity, which is a clean and renewable green energy.

Photovoltaic glass has the functions of protecting batteries from water vapor erosion, blocking oxygen to prevent oxidation, high and low temperature resistance, good insulation and aging resistance.

Photovoltaic glass can improve the light transmittance of glass, increase the transmittance of light, and improve the efficiency of photoelectric conversion.

Photovoltaic glass can save space and be installed on idle roofs or exterior walls without occupying additional land.

Photovoltaic glass can reduce the comprehensive outdoor temperature, reduce the heat gain of the wall and the cooling load of the indoor air conditioner, and play a role in building energy saving.

shortcoming:

Photovoltaic glass is expensive and requires professional installation and maintenance.

The power generation of photovoltaic glass is affected by sunshine conditions and seasonal changes, which is unstable.

Photovoltaic glass may have quality problems such as self-explosion, delamination, blistering, bulging, and yellowing, which affect service life and safety.

Photovoltaic glass needs to be connected to the grid and is restricted by grid policies and prices.

What is the definition and difference between distributed photovoltaic and building integrated photovoltaic (BIPV)?

When it comes to photovoltaic (photovoltaic) systems, distributed photovoltaics and building-integrated photovoltaics (BIPV) are two related but distinct concepts. Here are their definitions and differences:

Distributed Photovoltaics:

Definition: Distributed photovoltaic refers to a photovoltaic system that installs solar photovoltaic panels at scattered locations in buildings, facilities or areas to generate electricity and meet local electricity demand.

Features:

a. Decentralized layout: Photovoltaic panels are installed in multiple locations, which can be the roof, wall or ground of a building, or the covering of a facility.

b. Grid connection: The distributed photovoltaic system is connected to the main power network through the grid, which can inject the power generation of multiple systems into the grid, and can also obtain supplementary power from the grid.

c. Satisfaction of electricity demand: distributed photovoltaic systems are designed to meet local electricity demand and reduce dependence on traditional power supply.

d. Scalability: Since the system is dispersed in multiple locations, the distributed photovoltaic system can be expanded as needed to accommodate power generation of different scales and demands.

Building Integrated Photovoltaics (BIPV):

Definition: Building-integrated photovoltaics is a photovoltaic system that integrates solar photovoltaic modules into the design and construction of the building itself to achieve simultaneous power generation and building functions.

Features:

a. Building structure: The photovoltaic modules of the BIPV system are designed to be combined with the building's exterior walls, roofs, windows, etc., replacing traditional building materials such as bricks, tiles, and glass.

b. Integrated design: The design of BIPV system takes into account the appearance, structure and functional requirements of the building to achieve beautiful and reliable photovoltaic power generation.

c. Dual function: In addition to power generation, BIPV system can also provide heat insulation, sunshade, protection and decoration functions of buildings.

d. Building integration: The photovoltaic modules of the BIPV system are tightly integrated with other systems of the building (such as the power system and ventilation system) to achieve efficient energy utilization.

the difference:

Installation location: Distributed photovoltaics can be installed in various locations of the building, including roofs, walls, and ground, while the photovoltaic modules of the BIPV system are designed and installed as part of the building.

Purpose and function: Distributed photovoltaics are designed to meet local electricity demand and inject the power generation of multiple systems into the grid, while BIPV not only generates electricity, but also has the functions of buildings, such as heat insulation, sunshade and decoration.

Design considerations: The BIPV system needs to match the appearance, structure and functional requirements of the building to achieve an integrated design, while the design of distributed photovoltaics pays more attention to power generation efficiency and system scalability.

Installation and integration: The installation of distributed photovoltaics is relatively simple, and photovoltaic modules can be added to existing buildings, while BIPV requires the integration of photovoltaic modules during the design and construction of buildings.

To sum up, distributed photovoltaics focus on power generation and meet electricity demand, which is achieved by installing photovoltaic systems in different locations; while BIPV systems are integrated into the design and construction of buildings, with both power generation and building functions, to achieve integrated photovoltaic solutions.

Investment cost and rate of return of distributed photovoltaics?

The investment cost and rate of return of distributed photovoltaics can vary due to factors such as project scale, location, type of photovoltaic modules, installation method, and electricity price policy. The following are some reference information on the investment cost and return rate of distributed photovoltaic projects in general:

1. Investment cost
Photovoltaic modules: Photovoltaic modules are the core components of distributed photovoltaic systems, and their prices depend on the type and brand. In the investment cost, photovoltaic modules usually occupy a large proportion.

Inverter: The inverter converts the direct current generated by the distributed photovoltaic module into alternating current, and the price of the inverter is also an important part of the investment cost.

Structural support and installation: The support and labor installation costs for installing photovoltaic modules are also included in the investment cost.

Cables and electrical equipment: Cable routing and electrical equipment are an essential part of the system and part of the investment cost.

System design and engineering: including system design and engineering costs.

2. Income and rate of return
Power generation income: Distributed photovoltaic systems generate income by injecting electricity into the grid or providing electricity for their own electricity consumption. Benefits are related to solar resources, system performance, and electricity price policies.

Saving electricity bills: Distributed photovoltaic systems can reduce electricity purchased from the grid, thereby saving electricity bills.

Energy subsidies: In some regions, the government may provide subsidies or incentives for solar photovoltaic power generation, which can also be a source of income. The rate of return can be assessed by calculating the payback period. ROI refers to the time required to pay back the investment cost, usually calculated in years. A shorter payback period means a higher rate of return.

It should be noted that the investment cost and rate of return of distributed photovoltaic projects will be affected by many factors, including energy policy, electricity price policy, solar resource conditions, project scale, component quality, etc. Before investing in distributed photovoltaic projects, it is best to conduct detailed economic analysis and feasibility studies to fully evaluate the potential returns and risks of the project.

Seven major changes that photovoltaic power generation has brought us

In recent years, the government has developed and utilized renewable resources such as solar energy on a large scale, cultivating the new energy industry as a strategic leading industry for a new round of economic growth, and promoting the construction of new energy projects. So, what opportunities for wealth creation does photovoltaics bring us, and what changes will it bring us? Sunpal will take you to see it together.

wealth creation opportunity
1. Industrial and commercial photovoltaic roofs

Today, a group of qualified industrial and commercial enterprises have installed distributed photovoltaic power generation systems on their roofs. Due to the need to control smog, the country will introduce relevant policies in more cities in the future to allow the installation of photovoltaic new energy systems on the roofs of industrial and commercial facilities and public facilities.

2. Carbon trading starts
Due to the needs of environmental protection, the country may restrict carbon emissions through carbon emission taxes. At this time, clean new energy photovoltaics have become the darling. Individuals or enterprises can join the carbon trading system by installing photovoltaic power plants, and get more by selling green electricity. income.

3. Low-carbon products are more popular
When a product is labeled with a green label for electricity, similar to foods with calories marked, and all products are marked with how much electricity was used to produce the product and how much carbon dioxide is produced, people will choose similar products with less carbon emissions to promote environmental protection.

4. Rural health benefits
The popularization of distributed photovoltaics can play a very good role in environmental protection. When various facilities in rural areas can use photovoltaics, the ecological environment in rural areas will also be greatly improved.

Photovoltaic changes every aspect of life

1. Fashion and beauty become the focus
The solar power system is equipped with beautiful buildings, elegant colors, fashion, and the overall effect is beautiful and atmospheric.

2. Energy saving, environmental protection and smog reduction
Photovoltaic power generation system is a safe, green and sustainable clean energy, which not only saves energy but also reduces carbon dioxide emissions, and the effect of planting trees can be achieved by generating electricity every day.

3. Heat insulation and cooling in summer
The solar cell module absorbs a wide range of spectra and can absorb solar radiation to a large extent, thus playing a good heat insulation effect.

In the realm of street lighting, the evolution of technology has led to the emergence of solar-powered alternatives alongside traditional grid-connected lights. This development raises the pertinent question: what sets solar street lights apart from their conventional counterparts? Let’s delve into the distinctions and advantages of each.

1. Power Source:

Solar Street Lights: These utilize photovoltaic panels to harness sunlight and convert it into electricity. This means they operate independently of the electrical grid, relying solely on solar energy. High efficiency small solar panels play a crucial role here, efficiently capturing sunlight and transforming it into usable power.

Normal Street Lights: Conversely, traditional street lights are powered by electricity from the grid. They require a constant connection to the power supply network, making them dependent on infrastructure and susceptible to power outages.

2. Environmental Impact:

Solar Street Lights: By harnessing renewable energy from the sun, these lights have a significantly lower carbon footprint compared to grid-powered lights. They contribute to reducing greenhouse gas emissions and mitigating environmental degradation.

Normal Street Lights: Grid-connected lights rely on non-renewable energy sources such as coal or natural gas, leading to higher emissions and environmental harm.

3. Installation and Maintenance:

Solar Street Lights: Installation of solar street lights is often simpler and more cost-effective since they do not require extensive wiring or trenching for power connections. Additionally, their off-grid nature means they can be conveniently portable, making them suitable for remote or temporary lighting needs. Small size solar panels off-grid power facilitates flexibility in placement and installation.

Normal Street Lights: These lights necessitate complex installation procedures involving trenching for underground wiring and connection to the electrical grid. Maintenance also requires periodic checks and repairs to the electrical components.

4. Cost Efficiency:

Solar Street Lights: While the initial investment for solar street lights may be higher due to the cost of photovoltaic panels and batteries, they offer long-term cost savings by eliminating electricity bills and reducing maintenance expenses.

Normal Street Lights: Although traditional street lights may have lower upfront costs, they incur ongoing expenses for electricity consumption and maintenance, making them less cost-effective in the long run.

The key disparities between solar street lights and normal street lights lie in their power source, environmental impact, installation, maintenance, and cost efficiency. Solar street lights, powered by conveniently portable small solar panels, offer a sustainable and independent lighting solution with minimal environmental footprint and long-term economic benefits. As the world embraces renewable energy technologies, solar street lights stand out as a beacon of innovation in the realm of urban illumination.