Photovoltaic energy storage is not the same as grid-connected power generation, to increase the battery, as well as battery charging and discharging devices, although the upfront cost to increase 20-40%, but the scope of application is much wider. According to different applications, solar photovoltaic energy storage and power generation system is divided into off-grid power generation system, and off-grid energy storage system, grid-connected energy storage system and a variety of energy hybrid micro-grid system and so on four kinds.
Photovoltaic off-grid power generation system
Photovoltaic off-grid photovoltaic power generation system (Off-Grid Photovoltaic Power Generation), solar cells in addition to embedded in the calculator, the simple application of the body of the electronic watch, with a solar panel, a simple charging device, the battery on the composition of the simplest photovoltaic power generation system, such a device is often used by the herdsmen to carry around the power supply for radio and Evening lighting. Now there are also such portable solar power.
Grid-connected and off-grid energy storage systems
Photovoltaic system according to the actual application of a variety of, which and off-grid energy storage system is characterized by both grid-connected power generation, but also energy storage, but also off-grid individual operation, in some commercial areas, because of the limited capacity of the transformer photovoltaic system issued by the power is not allowed to go online to sell electricity, but also have to the instability of the regional power grids, and there are also areas of the Internet price is too cheap single-use power prices are high, the peak and valley price difference is large, the installation of photovoltaic power plants in these areas Suitable for the use of on-grid and off-grid energy storage system.
Photovoltaic and off-grid energy storage system has four main ways to profit:
1. Using photovoltaic power supply to the load, you can set the price of electricity peak output, reduce electricity costs.
2. Charge at off-peak time and discharge at peak time, utilizing the peak and valley price difference to make profits.
3. Can not be online, can be installed to prevent back flow system PV power is greater than the load power, the power can not be used up to the battery storage.
4. Grid blackout, the system is switched to off-grid mode PV system continues to generate electricity, the system continues to work as a backup power supply, photovoltaic and battery power supply to the load through the inverter.
Relative to the grid-connected power generation system, and off-grid system increases the charge/discharge controller and battery, the system cost increased by about 30%, but the scope of application is wider. Firstly, it can be set to output at rated power at the peak of the electricity price to reduce the electricity bill; secondly, it can be charged at the valley of the electricity price and discharged at the peak to make money by utilizing the difference between peak and valley price; thirdly, when the grid is out of power, the PV system will continue to work as a back-up power source, and the inverter can be switched to off-grid mode, and the PV and the batteries can be supplied to the load through the inverter.
Grid-connected photovoltaic energy storage system
Photovoltaic power production systems with grid-connected energy storage can store excess power generation, increasing the proportion of self-generation and self-consumption. These systems are utilized in situations when PV self-generation and self-consumption cannot be fed into the Internet, peak tariffs are much more expensive than wave level rates, and self-consumption tariffs are significantly more expensive than feed-in tariffs. The system is comprised of a photovoltaic square array consisting of solar cell modules, a solar controller, a battery bank, a grid-connected inverter, a current detecting device, a load, and other components. The controller stores some of the solar energy and delivers some of it to the load when the solar power is greater than the load power. The system is powered by a combination of grid and solar energy when solar power is not enough to power the load. Following the withdrawal of photovoltaic subsidies, grid-connected energy storage systems can be installed prior to the installation of solar systems in some countries and localities, allowing photovoltaic power output to be completely self-generated and self-consumed. The grid-connected energy storage device can be utilized with inverters from various manufacturers while maintaining the original configuration. When the current sensor detects a current flow to the grid, the grid-connected energy storage device activates, storing excess electricity in the battery and, if the battery is full, activating the electric water heater. The battery can be set to send electricity to the load via the inverter when the household load increases at night.
Micro grid System for Energy Storage
A solar cell square array, a grid-connected inverter, a PCS bidirectional converter, an intelligent switching switch, a battery bank, and a generator comprise the micro grid system. burden, and so forth. When there is light, the photovoltaic array converts solar energy into electricity. It then uses the inverter to power the load and the PCS bidirectional converter to charge the battery pack. When there is no light, the battery uses the PCS bidirectional converter to power the load. The micro grid is the most efficient solution to assure power grid safety because it can fully and efficiently leverage the promise of distributed clean energy while minimizing the drawbacks of small capacity, unpredictable producing power, and low reliability of independent power supply. The system’s safe operation serves as a beneficial supplement to the massive power grid. Micro grids can considerably help traditional businesses modernize in terms of both economics and environmental protection. Experts say micro grid applications are diverse and can range in size from a few kilowatts to dozens of megawatts. Micro grids can be designed for as little as a single building to as large as industries, mines, companies, hospitals, and schools.
At the end of October 2020, the National Energy Administration approved the implementation of the “PV Power System Efficiency Code”, which fully liberalizes the capacity ratio of photovoltaic power stations, with a recommended capacity ratio of up to 1.
Opportunity: Domestic PV module shipments will continue to increase significantly over the long term, while inverter shipments will also increase. Reasonable over-allocation can realize the lowest LCOE, improve project IRR and accelerate the promotion of parity.
Challenge: Light abandonment and the volatility of PV power generation inverter’s overmatching and overload capacity.
Establishment of a sound energy storage industry standard system, energy storage system involves a lot of equipment links, industrial chain equipment performance varies, fire and other accidents is a key bottleneck affecting the development of energy storage.
Clarify the independent market status of energy storage, energy storage facilities can be combined with photovoltaic, thermal power and other power sources as a whole, to participate in the power system’s peak shifting and frequency shifting services, and gain revenue, but also as an independent market entity.
Diversified and stable policy support, industrial policy support for energy storage needs to be synchronized with marketization, while implementing diversified industrial policies for different application scenarios.
China’s future energy development will go through the process from high carbon to low carbon to zero carbon, new energy in the field of electricity from incremental replacement gradually began to stock replacement, respectively, to complete the user side of the energy storage + new energy. Power generation side of the energy storage + new energy parity. It is expected that by 2035, new energy sources such as photovoltaics will account for more than 30% of the energy mix, supporting the upward trend of energy consumption without increasing carbon emissions.
Whether the energy storage plant installed in the transmission example or power distribution whether with renewable energy field station sharing site, or independent access to the grid energy storage plant, are mainly from the power market benefit, mode diversification.
New energy toward clean renewable energy grid-connected energy storage development direction, in the form of wind and solar storage gradually around the world to start demonstrations. Energy storage supporting photovoltaic, wind power to bring the economic effect of continuous stabilization, regulation of wind and light abandonment, etc., have brought good improvement.
