What Are The Different Technologies Of Pv?

The photovoltaic (PV) effect was first observed in 1839 by French physicist Edmond Becquerel. The first solar cell made from silicon was created in 1883 by Charles Fritts. However, it took over half a century of improvements in materials and manufacturing before solar panels became a viable source of power generation.

Photovoltaic technologies refer to the methods and materials used to convert sunlight directly into electricity through the PV effect. This is done using solar cells made from semiconducting materials that exhibit the PV effect, such as silicon, cadmium telluride, and copper indium gallium selenide.

There are three main generations of photovoltaic technology that have been developed over the years. The first generation uses crystalline silicon cells, which currently dominate the market. The second generation uses thin-film technologies to reduce costs. Emerging third generation technologies aim to increase efficiencies and lower costs even further.

First Generation PV – Crystalline Silicon

The first generation of photovoltaic (PV) technology is based on crystalline silicon cells. This type of PV has been around since the 1950s and currently dominates the solar market, accounting for over 90% of PV installed worldwide. There are two main types of crystalline silicon cells:

Mono vs. Polycrystalline

Monocrystalline silicon cells are made from single crystalline silicon ingots, giving them a uniform black appearance. Polycrystalline silicon cells are made from molten silicon cast into ingots which have a varied crystal structure, resulting in a speckled blue color.

Monocrystalline cells typically have higher efficiencies of around 15-20%, compared to 13-16% for polycrystalline. However, polycrystalline cells tend to be slightly cheaper to manufacture. In terms of longevity, both cell types can last 20-30 years or more.

Efficiency, Costs, and Longevity

The average efficiency of most crystalline silicon modules today is between 15-18%. While crystalline silicon panels are more expensive than thin-film, costs have dropped dramatically in the last decade making them cost competitive. The life expectancy of these modules is over 25 years.

Main Manufacturers

Some of the major manufacturers of crystalline silicon PV include JinkoSolar, JA Solar, Trina Solar, Canadian Solar, and LONGi from China. SunPower and First Solar from the US, and Qcells from South Korea are also top producers.

Second Generation PV – Thin Film

Thin film photovoltaics represent the second generation of solar cell technology. As the name implies, thin film PV uses thin layers of semiconductor materials usually deposited on glass, stainless steel or plastic substrates. The most common types of thin film solar cells are cadmium telluride (CdTe), copper indium gallium selenide (CIGS), and amorphous silicon (a-Si).

Compared to traditional crystalline silicon cells, thin film PV offers some key advantages. The raw materials for CIGS and CdTe are more abundant and cheaper than silicon. Thin film modules are lightweight and flexible, enabling innovative applications not possible with rigid crystalline panels. However, thin film also has lower efficiency ratings, typically 10-20% versus 15-22% for crystalline silicon. The manufacturing process can use less energy but involves some toxic materials like cadmium and selenium.

Major manufacturers of thin film PV include First Solar, the largest global supplier focused on CdTe technology. Solar Frontier operates one of the world’s largest CIGS factories. Other companies like Sharp, Hanergy, and Kaneka produce thin film modules based on a-Si or a-Si/mc-Si technology. Overall, thin film represents about 10-15% of the total PV market today. As research continues, the mix of advantages could drive wider adoption of second generation thin film solar going forward.

Third Generation PV

Third generation photovoltaics refer to emerging PV technologies that aim to lower costs and improve efficiency beyond traditional crystalline silicon solar panels. Some key benefits of third generation PV include:

• Low manufacturing costs using inexpensive materials and processes
• Flexibility – can be made thin, lightweight and flexible
• Higher efficiencies in converting sunlight to electricity
• Use innovative materials like polymers, dyes, and perovskites

However, third generation PVs also have some drawbacks compared to conventional PV:

• Most technologies are still in early R&D or pilot stages
• Long-term reliability and durability remains unproven
• Efficiency levels drop faster than silicon PV
• Some use rare earth metals presenting supply chain risks

Major types of third generation PV include:

• Dye-sensitized solar cells (DSSC) – use photosensitive dye molecules to absorb light
• Organic photovoltaics (OPV) – use carbon-based polymers and molecules to absorb light
• Perovskites – emerging tech using hybrid organic-inorganic perovskite structures

In summary, third generation PVs introduce innovative designs and materials to push solar technology to the next level. But work remains to improve efficiency, durability, scalability, and commercial viability.

Balance of System Components

In addition to the solar panels themselves, complete photovoltaic (PV) systems require various balance of system (BOS) components that support, monitor and optimize system performance. Some key BOS technologies include:

Inverters

Inverters convert the DC electricity generated by solar panels into AC electricity that can power homes and businesses while synchronizing seamlessly with the utility grid. Advanced inverters provide smart grid capabilities to manage two-way power flows and ensure safe, reliable system operation.

Charge Controllers

Charge controllers regulate the voltage and current from solar panels going into batteries to prevent overcharging. They extend battery life and ensure systems operate safely.

Batteries

Batteries store excess solar energy for use when the sun isn’t shining. They provide backup power and maximize self-consumption of PV energy. Lithium-ion batteries are becoming increasingly popular for home and grid applications.

Racking and Trackers

Racking provides the mounting structure to affix solar modules in the desired orientation. Single-axis trackers automatically pivot panels to follow the sun over the course of a day, increasing energy production. Rooftop systems use fixed tilt or pole mounts tailored to the roof shape and orientation.

Monitoring

Monitoring hardware and software provides system performance data to the owner/operator and identifies faults or needed maintenance. Remote monitoring capabilities allow solar fleets to be managed and optimized efficiently.

Residential PV Systems

Residential solar PV systems are typically in the range of 2-10 kilowatts and can provide a portion of a home’s electricity needs. The main components of a residential system include solar panels, inverters, racking, wiring, and monitoring systems. Systems are usually roof-mounted but can also be ground-mounted or building integrated. Layouts can be fixed tilt or use one or two axis trackers to follow the sun. Tracking systems can generate 10-25% more energy but have higher costs and maintenance requirements.

Pros of residential PV include reducing electricity bills, increasing home value, achieving energy independence and having a sustainable power source. Cons are the still high upfront investment required, though costs have fallen sharply. Lifetime costs of a residential system are in the $15,000-$30,000 range. Return on investment varies greatly depending on local electricity rates, incentives, and solar resource. Payback periods range from 5-15 years for purchased systems.

Homeowners can choose to purchase a turnkey system from a solar installer or do a DIY installation. Professional installs cost more but include system design, permitting, installation labor and maintenance. DIY installs require expertise in electrical work and involve more risks. Either option allows the homeowner to own the system instead of leasing from a solar provider.

Commercial PV Systems

Commercial PV systems are designed to generate power for commercial buildings like offices, retail stores, warehouses, hospitals, schools, etc. The system design depends on the size and power needs of the facility as well as local regulations. Some key considerations for commercial PV system design are:

• Roof type and structural capacity
• Optimal tilt and orientation to maximize solar production
• Type of PV panels and racking system
• Inverter size and electrical connections
• Monitoring and maintenance requirements

There are attractive financial incentives for commercial solar installations like federal tax credits, accelerated depreciation, solar renewable energy credits, and net metering savings on utility bills. Many national and regional solar companies focus on commercial PV system installation and management including SolarCity, SunPower, Sunrun, Sunnova, and groSolar.

Some impressive commercial solar projects include the Target store in California with a 1.1 MW rooftop system, the IKEA store in Maryland with 1.7 MW on its roof, and the Crayola manufacturing facility in Pennsylvania with a 6.3 MW ground-mounted system powering 30% of their operations.

Utility-Scale PV Plants

Utility-scale photovoltaic (PV) plants generate solar power to feed into the grid, providing clean renewable electricity at scale. These plants install PV modules over large ground area sites or on elevated mounting structures, and range from a few megawatts to gigawatt-scale facilities.

There are several key considerations and technologies for building utility-scale PV plants:

• Ground-mounted vs. elevated mounting: Ground-mounted is more common for flat open spaces, while elevated mounting on poles or racks allows for other uses like grazing under the panels. Elevated mounting requires more steel and construction but avoids shading.
• Tracking systems: Single-axis tracking rotates panels along one axis to follow the sun, while dual-axis provides full 360-degree tracking for maximum production. Tracking adds significant cost but can improve energy yield up to 30%.
• Power plant components like inverters, transformers, monitoring and control systems to harvest and deliver the solar electricity.

Some of the world’s largest operating solar PV plants include:

• Bhadla Solar Park in India – 2.2 GW capacity.
• Tengger Desert Solar Park in China – 1.5 GW capacity.
• Villanueva Solar Park in Mexico – 1.4 GW capacity.
• Kurnool Ultra Mega Solar Park in India – 1 GW capacity.

Utility-scale PV represents a rapidly growing segment of solar, led by demand from corporations and electric utilities seeking clean energy at competitive pricing.

Emerging Applications

Photovoltaic technology is finding innovative new uses beyond traditional solar panels. Some emerging applications of PV include:

Building Integrated PV (BIPV) – Solar cells are integrated into the roof, facade, windows or other elements of a building as part of the overall architecture and construction. This allows buildings to generate their own electricity while serving as a structural component.

Vehicle Integrated PV (VIPV) – PV technology is integrated into cars, buses, trucks, trains and other vehicles to help power electric motors and reduce fossil fuel consumption. Solar vehicles could play a key role in sustainable transportation.

Solar Roads – Roads and highways paved with solar panels could produce electricity while allowing vehicles to drive over them. Projects exploring solar roads have emerged in China, France, the Netherlands and the US.

Solar Aircraft – Electric planes and unmanned aerial vehicles powered by PV cells are being developed. Airbus has already successfully flown a solar powered aircraft prototype.

Spacecraft – PV technology powers many spacecraft and satellites. Flexible and lightweight solar arrays are an enabling technology for space exploration and research.

As photovoltaics become more efficient and cost-effective, we may see many more innovative applications emerge. PV could play a larger role in sustainable mobility, infrastructure, architecture, aerospace and beyond in the future.

Conclusion

This article has discussed the range of available photovoltaic (PV) technologies, from the silicon-based first generation through thin films and emerging third generation types. We’ve seen how crystalline silicon dominates today’s market, while CdTe thin films have made great strides in lowering costs. Newer technologies like perovskites and organic PV show promise to push efficiencies higher and costs lower.

On the system side, we looked at residential rooftop PV providing clean onsite power to homes. At larger scales, commercial buildings can utilize PV to offset consumption, while utility plants generate solar electricity to feed into the grid. With PV modules embedded into building materials or vehicles, exciting new form factors are emerging.

Looking ahead, solar PV is poised for tremendous growth globally. With costs declining and efficiencies improving, solar electricity is increasingly competitive with fossil fuels. Supportive policies, electrification trends, and carbon reduction goals will further drive PV adoption. However, work remains to integrate more renewables into grids and develop storage solutions. Overall, the future is bright for PV playing a major role in the world’s clean energy transition.