With the development of the global energy storage market, photovoltaic energy storage can store excess electricity for use at night or on cloudy days. This article will give a comprehensive introduction to this energy storage method.
1. What is a photovoltaic energy storage system?
Photovoltaic storage storage system is a new energy power generation system composed of photovoltaic equipment and energy storage equipment.
2. What is the function of photovoltaic energy storage system?
One of the most important functions of photovoltaic distribution and energy storage is to improve the reliability of the power system and maintain the stability of the output of the entire power system. At the same time, photovoltaic energy storage can also provide energy backup, increase the utilization hours of photovoltaic power generation, and increase the income of the project.
3. What are the application scenarios of photovoltaic energy storage systems?
On the DC side of photovoltaic power generation, the investment will be invested by photovoltaic energy storage investment. After the photovoltaic system sends direct current, it directly enters the energy storage system.
- The AC side of photovoltaic power generation is invested by photovoltaic investment. It can be on the AC side inside the power plant, or it can be built by the power generation company on the AC side outside the power plant.
- The side of the power grid where the investment and construction are led by the power grid.
- The load side of industrial and commercial and user investment and construction.
4. The role of photovoltaic energy storage application scenarios
- The power generation side of the photovoltaic energy storage is mainly used to stabilize the fluctuation of new energy, track the power generation plan of the power grid, and alleviate the abandonment of wind and light.
- The power transmission and distribution side mainly ensures the safe and reliable operation of the power grid, and participates in power grid auxiliary services such as peak shaving, frequency regulation, and black start.
- The user side is mainly applicable to peak-valley arbitrage, dynamic capacity expansion, and demand-side response.
- Peak-valley arbitrage is due to the fact that the industrial and commercial electricity prices on the user side have peak-valley electricity prices, charging during valley hours and discharging during peak hours, which reduces the cost of buying electricity from the grid during peak hours in photovoltaic energy storage.
5. Advantages and disadvantages of four application scenarios of photovoltaic energy storage
5.1 DC side of power generation
- Applicable scenarios
- The newly built capacity and distribution ratio is high, and the DC side limit of the power station is serious
- Power stations with large fluctuations in photovoltaic energy storage output and poor power quality
- Power stations without additional grid connection points and without access conditions
- Advantages
- Reduce light abandonment and improve equipment availability
- It can generate power for photovoltaic output and supplement the insufficient power when the light is weak
- Increase the available hours of the power station and increase revenue
- No need for separate network access procedures, short construction period
- Disadvantages
- China’s DC-side photovoltaic energy storage cannot be used as a photovoltaic distribution and storage indicator for the time being
- China’s photovoltaic on-grid electricity price is low, and it is difficult to support the cost only by electricity price
- Photovoltaic fields are scattered and arranged, making operation and maintenance difficult
5.2 AC side of power generation
- Applicable scenarios
- Large single power station
- The revenue model is not yet clear, and cost is the primary consideration
- Meet grid-connected requirements and require high control accuracy and reliability
- Advantages
- Promote new photovoltaic energy storage consumption
- As a support point of the power grid, improve the stability of the power grid
- Â Disadvantages
- Connected at the end of the power grid, the effect on system auxiliary services is not obvious, the willingness to dispatch the power grid is not high, and the income of auxiliary services is difficult.
- The photovoltaic energy storage system utilization rate is low, and the value is not obvious
5.3 AC side of power generation
- Applicable scenarios
- Large-scale single power station
- Revenue models are diversified, and photovoltaic energy storage system availability is getting more and more attention
- Meet grid-connected requirements and require high control accuracy and reliability
- Â Advantages
- Can meet the allocation and storage requirements
- Large-scale construction, low system cost
- Independent operation, stronger professionalism
- Diversified income sources, suitable for market-oriented development
- Disadvantages
No obvious disadvantages in photovoltaic energy storage
5.4 Grid side
- Applicable scenarios
- Large-scale single power station
- The income model is higher than that of the power supply side, and the cost is not the decisive factor
- Satisfies the dispatching requirements of the power grid of the photovoltaic energy storage, and requires high system reliability and convenient operation and maintenance
- Advantages
- As a reserve capacity, participate in power grid dispatching
- Participate in power spot transactions and promote the development of smart grids
- Disadvantages
- No fixed photovoltaic energy storage income model
- Policies on the grid side are unclear
5.5 User side
- Applicable scenarios
- Single power station is small in scale
- The main profit model is peak-valley arbitrage, pursuing single Wh income. Sensitive to capacity utilization.
- Simple control logic
- Â Advantages
- Improve photovoltaic energy storage power generation revenue
- Dynamic capacity increase to ease the load pressure on the power grid
- Value arbitrage, providing ancillary services (FM, black start)
- Participate in demand-responsive markets
- Disadvantages
- Single revenue model
- Uncertainty about electricity price policy
6. Two major profit models for industrial and commercial optical storage systems
The commercial and industrial energy storage system is mainly to meet the internal power demand of industrial and commercial users and realize the maximum utilization of photovoltaic photovoltaic energy storage power generation. Profit models include peak-valley arbitrage and electricity cost savings.
Peak-valley arbitrage refers to using low-price electricity to charge during low electricity consumption, and discharge it to supply industrial and commercial users during peak electricity consumption. Users can save electricity costs and avoid the risk of power cuts.
7. Photovoltaic energy storage product introduction
The parameters and specifications of photovoltaic energy storage are based on HuntKey’s 173kWh C & I energy storage system cabinet.
| Specification | Parameter |
|---|---|
| name | 173kWh C & I energy storage system |
| Rated Power | max100kW |
| AC output voltage | 380VAC |
| Frequency | 60HZ |
| Nominal Energy | 173kWh |
| Voltage and capacity | 656.6V 260Ah |
| DC voltage range | 580V-730V |
| Communication | 485,CAN Ethernet |
| Protection Degree | IP54 |
| Thermal management | Air conditioning cooling |
| Dimensions(W*D*H) | 2000*1280*2218mm |
| Firefighting system | Heptafluoropropane |
| System topology | AC couple |
8. Interpretation of key parameters of industrial and commercial solar energy storage systems
- Output Power
There are two expressions for the output power of the energy storage inverter, one is the apparent power representation, and the unit is VA, which is marked with reference to the UPS energy storage, and the actual output active power must be multiplied by the power factor. The second is active power representation, the unit is W.
In off-grid applications, the output power of the photovoltaic energy storage inverter is determined by the load. For some inductive loads, such as air conditioners and water pumps, the starting power of the motor inside is 3-5 times the rated power. There are special requirements for overloading, and the peak power is the overloading capacity of the system when off-grid.
Maximum photovoltaic power
Refers to the maximum module power that the inverter can access. Due to the power consumption and usage time of energy storage inverter users, there are many types, so the capacity range of photovoltaic modules is required to be relatively wide.
The photovoltaic energy storage controller adopts a modular design, 60kW is a module, which is convenient to choose the module capacity according to the actual situation of the customer.
If the customer needs less power, the optical storage system is only a backup power supply, and fewer components can be designed. If the customer needs a lot of power, more components can be designed.
Cycles
The number of cycles refers to the number representing the total number of full and partial discharge cycles over the life of the battery.
The number of lithium battery cycles refers to the total number of all and partial discharge cycles in the entire battery life. When the battery is discharged to 50% of the power, two discharge cycles are counted as one discharge cycle, and this discharge cycle is counted as the number of cycles.
The number of cycles of the battery and the charging cycle are inseparable. The number of cycles is actually a calculation method of the charging cycle. When the battery reaches a complete charging cycle, the number of battery cycles will be +1.
In addition, when charging a lithium battery, the recommended use window is 10% to 90%. Do not perform deep charge and discharge, so as not to cause irreversible damage to the positive and negative electrode structures of the battery.
- Degree of protection
Attention should be paid to outdoor installation applications and practical applications in high-altitude areas. In high-altitude areas, the air density decreases, the atmospheric pressure decreases, and the melting point and boiling point of the contact material also decrease. Under the high temperature of the arc current, the sublimation of the contact material of photovoltaic energy storage is faster than that at low altitude.
In high-altitude areas, the breaking capacity of the switch will also decrease, because as the altitude increases, when selecting a switch, the breaking capacity should be selected to a higher level. At the same time, high-altitude areas have a greater impact on energy storage batteries.
Due to the increase in altitude, the atmospheric pressure decreases, the heat dissipation performance of the photovoltaic energy storage battery decreases, the temperature rise during charging and discharging will increase, and the temperature difference will also increase. It is not conducive to the use and life of the battery, and the thermal stability of the battery gradually decreases with the increase in altitude.
F&Q
How do solar panels of photovoltaic energy storage work and store energy?
Solar technology converts sunlight into electricity through photovoltaic (PV) panels or through mirrors that concentrate solar radiation. This energy can be used to generate electricity or stored in batteries or thermal storage.
Do solar panels store energy for night?
Solar panels don't work at night in most places, but some places on Earth receive daylight 24 hours a day at certain times of the year. In northern Finland, the sun never sets for 60 days in summer. In theory, this allows the solar panels to generate electricity at night.
Of course, solar panels can be quite inefficient in locations exposed to midnight sunlight. The solar cells work at night to take full advantage of the daytime output of the panels. Solar panels supplement the battery with energy from the sun. Therefore, electricity can be stored for use at other moments of need in the future.
Is solar energy of photovoltaic energy storage stored as DC or AC?
Solar panels of photovoltaic energy storage generate direct current (DC) electricity, batteries store electricity, and the grid and most household appliances use alternating current (AC) electricity.
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