What is a grid-tied solar system?
A grid-tied solar system (GTS) is a system that connects solar power to the grid. Such a system converts sunlight into electricity through solar photovoltaic (PV) panels and transmits it to the grid, as well as obtaining the required power from the grid when solar power is insufficient. The main characteristic of a grid-connected solar system is its dependence on the grid for operation, even without energy storage.
Grid-connected solar systems typically include several key components: solar photovoltaic (PV) panels, inverters, and meters. Solar PV panels are responsible for converting sunlight into direct current (DC), and then the inverter converts the DC to alternating current (AC) for use in a home or commercial building. Excess power that is not immediately used is automatically fed back into the grid.
The advantages of this system are its simplicity and cost-effectiveness. Since no energy storage is required, the system is relatively easy and inexpensive to install and maintain. In addition, users can sell excess power to the grid through net metering, thereby reducing their electricity bills. However, a disadvantage of this system is that it also stops working when the grid goes down, as safety regulations require that power be cut off in the event of a grid failure.
Grid-connected solar systems are an affordable and widely used solar solution for homes and businesses that want to utilize solar energy to reduce their electricity bills while keeping power on the grid.
The latest technological advances in grid-connected solar systems are focused on the following areas:
Advances in PV module technology:
PV technologies such as polycrystalline silicon, monocrystalline PERC and monocrystalline PERC HC are widely used. Polycrystalline silicon is recommended for projects due to its easy availability, cost-effectiveness and technological stability.
Improvement in PV cell efficiency and reduction in manufacturing cost is one of the key factors for the rapid development of PV technology.
Optimization of inverters and power electronics:
Grid-connected interactive inverters convert DC to AC and increase the voltage through a step-up transformer for final connection to the grid. Intelligent control algorithms and advanced power electronics technologies can monitor the status of the grid in real time and automatically adjust the output of PV power generation to ensure stable operation of the grid.
Integration of energy storage technology:
The development of energy storage technology provides new ideas for solving the grid-connection problem. By integrating energy storage equipment in the PV system, the volatility of PV power generation can be effectively smoothed out and the reliability of the grid connection can be improved.
System design and modularization:
PV systems are highly modular and modules can be connected in series to provide power ranging from a few watts to tens of megawatts.
The 1500V system becomes critical to support multiple access modules in a single string, reducing the number of strings and lowering the cost of inverters and convergence boxes.
Safety and Reliability:
Flexible racking technology solves the problems of large land area occupied by PV racking piles and limited agricultural farming.
DC arc monitoring sensors and other intelligent systems are applied to PV convergence boxes, DC cabinets and other occasions to detect DC circuit faults in real time and improve system safety.
Policy and market promotion:
National policy encourages the development of intelligent PV modules, inverters, controllers, convergence boxes, tracking systems and other key components, and promotes the quality and efficiency of PV products and technologies.
The implementation of the new PV grid connection regulation “Technical Provisions on the Access of Photovoltaic Power Stations to Electric Power Systems” promotes the cost reduction and efficiency of PV systems.
System integration and application:
Grid-connected photovoltaic power generation system can not only be converted into solar energy under the role of the inverter into an AC load for users to use directly, but also the converted power to the AC power grid transmission. Grid-connected solar systems enable users to take full advantage of solar power by seamlessly integrating with the local power grid, while still having access to utility power when needed.
How can the safety of grid-connected solar systems be addressed in the event of a grid outage?
The safety of grid-connected solar systems during grid outages can be addressed in several ways:
Anti-islanding operation technology: Grid-connected inverters should be equipped with anti-islanding operation technology, capable of timely unlinking with the grid and stopping power delivery to the grid when grid outage is detected, in order to protect personal and equipment safety.
Independent power supply and automatic synchronized grid operation technology: the system can realize automatic delinking with the grid when the grid is out of power, and independently provide high-quality AC power to important loads. If the system is equipped with a storage battery, it can also provide uninterrupted power at night.
Hybrid system: A hybrid system, combined with battery storage to provide backup power, ensures uninterrupted power supply even when the grid is temporarily unavailable. Such systems can automatically switch to off-grid mode in the event of a grid outage, using solar panels or batteries to power the home.
New inverters: Using the new SMA inverters with Safe Power features, homes can be powered even during blackouts without the need for additional energy storage systems.
Battery Backup: Add batteries to your solar system to create a solar + storage hybrid system that provides backup power during grid outages. During normal operation, the batteries store excess solar energy for later use.
Hybrid Inverter: Using a hybrid inverter in conjunction with a battery system ensures that critical loads can still be powered in the event of a grid failure, but without feeding energy back into the grid. This configuration reduces on-site fuel storage, extends fuel life cycles, and ensures power availability during extended or emergency outages.
Average cost and long-term economic benefit analysis of grid-connected solar systems.
The average cost and long-term economic benefits of a grid-connected solar system are analyzed below:
Average Cost
Initial Investment Cost:
The initial investment cost of a grid-connected solar system varies depending on factors such as system size, location, and module type. Typically, the cost per watt is between $8 and $10. For example, a 5 kW PV plant has an upfront investment cost of about $20,000-$30,000 and an end cost of about $5-5 per watt.
For a household PV power plant, the installation capacity is usually 3-10 kW, and the system investment is around 60,000-120,000 RMB.
In the United States, a typical grid-connected solar system costs between
between 14,000, net of federal solar tax credits.
Maintenance and Operating Costs:
Maintenance and operating costs are relatively low and center around regular cleaning of solar panels and possible inverter replacement (usually after 10 to 15 years).
The efficiency of solar panels declines at a slower rate, maintaining 80 to 90 percent of their original capacity even after 25 to 30 years.
Long-Term Economic Benefits
Electricity bill savings:
Grid-connected solar systems return excess power to the grid through “net metering,” which reduces or offsets the cost of power taken from the grid at night or on cloudy days.
For example, a 10 kW PV system on a 100-square-meter rooftop generates about 9,500 kWh of electricity per year, and at a feed-in tariff of $0.80/kWh, it generates about $20,000 per year.
Government subsidies and tax credits:
Tax credits offered by the government (e.g., the 26% federal solar tax credit) can significantly reduce the initial cost of a solar system.
In addition, some states and localities offer additional incentives to further reduce system costs.
Return on Investment (ROI):
The payback time for investing in a 5 kW grid-connected solar PV project is typically between 5-10 years, depending on factors such as the amount of electricity generated by the PV system, the price of electricity, and policy support.
The revenue and payback time for a home installation of 100 square meters of solar PV varies depending on regional subsidies and system efficiency, with a payback period of around 4-7 years.
Long-term gains:
As electricity prices rise, the return on solar investment will increase. Solar systems have a lifespan of more than 20 years and low maintenance costs, limited mainly to regular cleaning of the panels.
Conclusion：
The average cost and long-term economics of a grid-connected solar system depend on a variety of factors, including system size, location, module type, government subsidies and tax credits.
What are some use cases for grid-connected solar systems in combination with energy storage systems?
The use cases for combining grid-connected solar systems with energy storage systems focus on the following areas:
Home PV energy storage systems:
The home PV energy storage system is constructed through components such as solar arrays, grid-connected inverters, BMS management systems, battery packs and AC loads. When the utility power is normal, the system is powered by both the PV grid-tie system and the utility power to supply the loads; when the utility power is cut off, the energy storage system and the PV grid-tie system jointly supply the power to ensure that the household can still use electricity when the power is cut off. This type of system not only saves on electricity bills, but also provides a backup power source to enhance the quality of life.
Commercial and industrial PV energy storage systems:
Commercial and industrial photovoltaic energy storage systems are widely used in factories, businesses and other places to take advantage of peak and valley price differences or to cope with power outages. The system consists of solar modules, convergence boxes, solar on-grid and off-grid integrated machines, battery packs, wind turbines, loads and power grids. When there is light, the photovoltaic array converts solar energy into electricity, which is supplied to the load and charged to the battery through the inverter, and the excess electricity can be sent to the grid. When there is no light, power is supplied by the grid; when the grid is out of power, power is supplied by the battery through the inverter.
Wind and light storage grid-connected system:
Wind and light storage grid-connected technology combines wind and solar power generation with energy storage system and connects to the grid, realizing the synergistic operation between renewable energy power generation, energy storage and the grid through intelligent control and optimal scheduling. The system is able to smooth out the volatility and uncertainty of renewable energy power generation and ensure a continuous and stable supply of electricity.
Photovoltaic grid-connected energy storage system:
The PV grid-connected energy storage system combines photovoltaic power generation, energy storage devices and the AC grid with each other to realize the efficient use of clean energy. The system is capable of storing excess power generation, increasing the proportion of self-generation and self-consumption, and increasing the system’s profitability model by conducting scenarios such as peak and valley arbitrage and demand management through the energy storage device.
Optical storage microgrid system:
The photovoltaic storage microgrid system is a new type of network structure, consisting of distributed power supply, load, energy storage system and control device. Photovoltaic arrays convert solar energy into electricity in the presence of light, supply power to loads through inverters, and charge battery packs at the same time; in the absence of light, battery packs supply power to loads. Compared with the pure off-grid system, this system has a wider application range, more flexible configuration, higher efficiency and stronger load-carrying capacity.
