Photovoltaic (PV) systems are primarily classified into two categories: grid-connected (or grid-tied) systems, which are linked to the electricity grid, and stand-alone systems, which operate independently. Since the 1990s, the global market for solar energy has increasingly shifted toward grid-connected solar systems. By 2000, grid-connected systems had surpassed stand-alone systems in terms of market share, and by 2016, over 98% of solar cell production was deployed in grid-connected systems.
An on-grid solar system is a type of grid-connected PV system that works in harmony with the public electricity grid. The key advantage of these systems is the ability to manage energy flow both to and from the grid. With net metering, excess energy generated by the solar panels can be fed back into the grid, earning credits that can offset future electricity bills. On-grid systems do not require batteries, as they always have access to power from the grid when solar energy production is insufficient.
Essential Components of a Grid-Connected Solar System
A grid-connected solar power system consists of several crucial components, each playing a specific role in ensuring the system operates efficiently and safely. These include:
- Solar Panels: The heart of the on-grid system, solar panels capture sunlight and convert it into electrical energy. They account for more than 50% of the total cost of a solar system. The quality and efficiency of the panels directly impact the system’s overall performance.
- Solar Inverter: The solar inverter is a critical component in any grid-connected solar system. It converts the direct current (DC) electricity produced by the solar panels into alternating current (AC) electricity, which can be used by homes and businesses or fed into the grid. The inverter ensures the correct voltage and frequency for seamless integration with the grid.
- Panel Stands: Solar panel stands provide the structural support for mounting the panels. Typically made of durable materials like aluminum or galvanized iron, these stands can either be fixed or adjustable to track the sun’s movement. A high-quality panel stand is essential for the long-term stability and safety of the entire system.
- Solar Wires: Solar cables or wires are used to transfer electricity between the solar panels and the inverter. The cables are available in different types, primarily AC and DC wires, depending on whether the current is being transferred from the solar panels (DC) or from the inverter to the grid or household appliances (AC).
- DCDB / ACDB: A DC Distribution Board (DCDB) is used to connect the output of the solar panels to the inverter, while an AC Distribution Board (ACDB) ensures the distribution of power from the inverter to the connected load or the grid. Both are essential for the safe and efficient operation of the system.
- Earthing Kit: An earthing kit is used to protect the system from electrical faults, such as short circuits, and provides grounding to prevent electrical shocks or fires.
- Lightning Arrestor: A lightning arrestor is an important safety feature designed to protect the system from damage caused by lightning strikes. This device helps safeguard the solar panels, inverter, and other equipment from electrical surges.
- Net Meter & Solar Meter: Net metering allows homeowners and businesses with solar panels to send excess energy back to the grid and receive credits on their utility bills. The solar meter records the amount of solar energy produced, while the net meter tracks the energy sent back to the grid, facilitating billing and energy crediting.
- Safety Equipment: To protect the solar system from damage or malfunction, a variety of safety devices are used. These can include surge arrestors, circuit breakers, fuses, and grounding systems, which help prevent electrical faults and ensure the safe operation of the entire system.
- Installation Accessories: A range of installation accessories is also required, including wires, mounting structures, junction boxes, and other components necessary for assembling and setting up the system. Proper installation is key to ensuring the system operates efficiently and safely.
The Growing Adoption of On-Grid Solar Systems
The adoption of grid-connected solar systems has seen significant growth, particularly in developed countries, driven by falling prices of solar PV modules, government incentives, and increasing public awareness about the environmental benefits of renewable energy. Many homeowners, schools, offices, and public buildings are opting for rooftop solar installations to generate their own electricity and reduce reliance on fossil fuels.
Larger grid-connected systems, such as those installed in commercial buildings or solar power plants, can scale up from hundreds of kilowatts to several megawatts (MW), feeding energy directly into the grid. This reduces transmission losses and ensures that electricity is generated where it is needed most.
On the larger end of the scale, multi-megawatt solar power plants, often located in remote areas, feed all their generated power to the grid, contributing significantly to the overall renewable energy mix.
Benefits of On-Grid Solar Systems
On-grid solar systems offer several advantages:
- Cost Savings: With net metering, users can reduce their monthly electricity bills and, in some cases, receive credit for excess energy generated.
- Energy Security: The system ensures a reliable power supply, either from the solar panels or the grid, without the need for expensive batteries.
- Environmental Impact: By using solar energy, homes and businesses can reduce their carbon footprint and contribute to global efforts to combat climate change.
- Scalability: Whether for a small residential system or a large commercial installation, on-grid solar systems can be easily scaled to meet varying energy needs.
Net Metering Process: How It Works for Grid-Connected Solar Systems
Net metering is a key feature for grid-connected solar systems, allowing homeowners and businesses to sell excess solar power back to the grid. This means that if your solar system generates more electricity than you need, the surplus energy can be fed into the grid, and you’ll receive credits on your electricity bill for the energy provided. But how is the credit calculated, and is it truly beneficial to send excess power back to the grid? Let’s explore how net metering works and answer these important questions.
In countries like Australia, Canada, Italy, Spain, Denmark, and the United States, net metering has been a successful program for encouraging solar energy adoption. These nations have implemented net metering policies that allow consumers to generate renewable energy onsite and receive compensation for their excess power, making on-grid solar systems a popular choice.
In India, net metering has the potential to serve as a major incentive to increase consumer investment in rooftop solar and other onsite renewable energy generation solutions. The adoption of grid-connected solar systems has been growing rapidly in India, with ground-mounted solar installations exceeding the 9 GW target for 2017-18, reaching a total of 9009.81 MW. While most Indian states have introduced net metering policies to encourage solar energy, challenges still exist, particularly with grid integration and the financial health of DISCOMs (Distribution Companies). These issues need to be addressed to unlock the full potential of net metering and make solar energy more accessible to consumers across the country.
By facilitating the sale of excess solar energy back to the grid, net metering offers a clear financial benefit to users, while promoting sustainable energy generation and helping to reduce overall grid dependency.
Conclusion
On-grid solar systems represent the future of renewable energy generation for homes, businesses, and communities. With their ability to integrate with the grid and reduce electricity costs through net metering, grid-connected solar systems provide a practical and environmentally friendly solution to the energy challenges of the 21st century. As technology continues to improve and costs decrease, these systems are expected to play a critical role in the global transition to sustainable energy.