China adopts a two-part electricity price system for large industrial electricity users with a capacity of 315 kVA or above. The two-part electricity price system includes a basic electricity price and a kilowatt-hour electricity price.
The basic electricity price reflects the capacity cost in the enterprise cost, that is, the fixed cost part. The basic electricity fee can be calculated in one of three ways: transformer capacity, contract maximum demand, and actual maximum demand. The basic electricity fee paid by users each month is only related to their capacity or maximum demand, and has nothing to do with their actual electricity consumption.
The electricity price reflects the electricity cost in the enterprise’s electricity cost. When calculating the electricity price, the actual electricity consumption of the user is used as the basis for billing.
The sum of the two electricity prices calculated separately is the total electricity fee that the user should pay.
| Electricity costs | ||||
| Basic electricity fee (demand/capacity fee) (choose one of the three) | Electricity fee = actual electricity consumption x unit electricity price | |||
| Transformer capacity = transformer capacity x capacity electricity price | Contract maximum demand | Actual maximum demand = Actual maximum demand x demand price | ||
| Actual maximum demand > 105% of the approved demand value * The basic electricity fee for the part exceeding 105% will be doubled. | Actual maximum demand < 105% of the approved demand value◆Charged according to the approved demand value | |||
So, how can industrial and commercial energy storage save costs for enterprises by reducing demand/capacity electricity charges?
When the fixed capacity of the transformer is used for calculation, the price is fixed. When the maximum demand of the transformer is used for calculation, the electricity price is related to the power of the system during a certain period of time. After the enterprise installs the energy storage system, the power of the energy storage machine can replace part of the transformer capacity to supply power to the load, which plays a role in smoothing the load power peak and reducing the overall capacity demand, thereby reducing the capacity electricity charge of the transformer.
Here are some key strategies:
First, the energy storage system can release the stored energy during peak hours, thereby reducing the demand for the power grid and reducing the demand electricity charges. Since the electricity price is usually higher during peak hours, enterprises can not only reduce electricity bills but also ensure the stability of power supply by balancing the load with energy storage systems.
Second, the energy storage system can help enterprises optimize the power structure and reduce the demand for power capacity. By properly configuring energy storage equipment, enterprises can store electricity during low-price periods and use the stored energy during high-price periods, thereby reducing the overall demand for power capacity and reducing basic electricity charges.
In addition, the energy storage system can also provide enterprises with emergency backup power functions to ensure the power supply of enterprises in emergencies. This can not only avoid production interruptions caused by power outages, but also avoid additional costs caused by insufficient demand or capacity.
Let’s take a simple example: suppose the demand electricity price of a certain voltage level in a certain area is 40 yuan/kW/month. The power of the enterprise is 800kW in most periods, and only 1300kW in some periods.
Before installing the commercial battery energy storage system:
The transformer demand electricity fee is 1300kW*40RMB/kW·month = 52,000RMB per month.
After installing the 500kW/1045kWh energy storage system:
During the peak period, the transformer power is maintained within 800kW, then the transformer demand electricity fee is 800kW*40RMB/kW·month = 32,000RMB/month, which can reduce the basic electricity fee by 20,000RMB per month.
In addition to being a profit model of peak load shaving and valley filling, industrial and commercial energy storage systems can also effectively reduce demand/capacity electricity charges by balancing loads, optimizing power usage structure, and providing emergency backup functions, saving costs and improving efficiency for enterprises. With the continuous advancement of energy storage technology and the reduction of costs, it is believed that more and more companies will choose to use energy storage systems to reduce electricity expenses.
Exploring Investment Models for Industrial and Commercial Energy Storage Power Stations
At present, there are three main construction models for industrial and commercial energy storage: owner-invested, energy contract management and financial leasing.
(1) Owner-invested model, that is, the enterprise owner invests in the construction of industrial and commercial energy storage power stations, generally through the peak-valley arbitrage model to obtain income, with the fastest payback period, suitable for enterprises with sufficient funds.
(2) Energy management contract model (EMC), in simple terms, is a third party to invest, build and operate, the enterprise only needs to provide the site for the construction of the energy storage system, and the income obtained is divided between the investor and the enterprise according to the contract agreement.
(3) Financial leasing model, the enterprise introduces a financing company as the investor of the energy storage power station. During the lease period, the ownership of the energy storage power station belongs to the financial leasing party. The owner generally repays the rent through peak-valley arbitrage and other income. After the expiration of the term, the owner can obtain ownership and enjoy all the income.
Applications and Value of Industrial and Commercial Energy Storage Systems
(1) Peak shaving and valley filling: Utilize the difference in peak-valley electricity prices to charge during valley and flat periods and discharge during peak and peak periods to reduce the electricity costs of enterprises.
(2) Balancing demand charges: Energy storage systems can shave peaks and valley fill, eliminate peak loads, smooth the electricity curve, and reduce demand charges.
(3) Dynamic capacity expansion: The user’s transformer capacity is fixed. Generally, when the user needs the transformer to operate at overload during a certain period of time, the transformer capacity needs to be expanded. After installing a matching energy storage system, the transformer load can be reduced during this period through energy storage discharge, thereby reducing the cost of transformer capacity expansion and transformation.
(4) New energy consumption: Maximize the consumption of local new energy power generation and maximize profits.
(5) Improve power quality: Energy storage systems can improve three-phase imbalance and related power quality issues.
(6) Improve power supply reliability: The supporting energy storage system can ensure that power and production restrictions are not affected and ensure the normal operation of key loads.
(7) Demand-side response: After installing the energy storage system, if the power grid issues a demand response, the owner can participate in the demand-side response transaction through the energy storage system and receive additional compensation.
Can Peak-Valley Arbitrage and Capacity Management Be Achieved Simultaneously? Is Maximum Demand Setting Possible?
Capacity management and maximum demand control correspond to the basic electricity billing rules of the owner. If the user’s basic electricity fee is charged according to the transformer capacity, it corresponds to the capacity management function; if the basic electricity fee is charged according to the maximum demand of the transformer, it matches the maximum demand control function. The specific function implementation mechanism is as follows:
Capacity management requires setting the maximum power consumption according to the transformer capacity. The total charging power of the energy storage system in the peak-valley arbitrage mode and the owner’s load power does not exceed the maximum limit. The EMS dynamically adjusts the energy storage charging power to achieve this. Therefore, the peak-valley arbitrage and capacity management functions do not conflict and can be achieved at the same time.
The maximum demand control sets the maximum demand control value based on the electricity consumption data and production conditions provided by the owner. The EMS dynamically adjusts the energy storage charging and discharging power to reduce the owner’s maximum demand or realize the peak-valley arbitrage of the energy storage system without generating additional maximum demand electricity charges for the owner.
Do Energy Storage Systems Experience Losses? What is Their Operational Efficiency?
In addition to battery charging and discharging, the internal fire monitoring, air conditioning and temperature control systems of the energy storage system require external power supplies, which will cause some energy losses. The losses need to be taken into account and deducted when calculating the revenue.
According to the comprehensive efficiency calculation of the whole year under standard working conditions: the first-year system operating efficiency of the Standard Air-cooled All in One Cabinet of SmartPropel Energy Storage is more than 88% (including self-consumption of electricity); the first-year system operating efficiency of the standard liquid-cooled integrated cabinet is more than 89% (including self-consumption of electricity).
Can Charging and Discharging Data of Energy Storage Stations Be Exported?
There are two situations in which the charging and discharging data of the energy storage power station can be exported through the EMS cloud platform:
(1) Directly export PCS metering data. The data can reflect the PCS charging and discharging amount, including daily charging and discharging amount and monthly total charging and discharging amount, but this data is not recommended as a standard for customers to settle electricity bills.
(2) The customer has installed a metering meter, and the metering meter has communicated with EMS. The metering meter has a time-of-day metering function. The charging and discharging amount of the energy storage cabinet can be exported through the EMS cloud platform account, including daily charging and discharging amount and monthly total charging and discharging amount.
Will Building a New Energy Storage Station Affect the Revenue of an Existing Third-Party Solar Power Plant?
The impact of the new industrial and commercial energy storage system on the original photovoltaic revenue mainly depends on the photovoltaic consumption status. Specifically:
(1) If the enterprise still has a large load demand after consuming all the photovoltaic power during the day, the energy storage system will have no impact on the photovoltaic revenue as a supplementary power.
(2) If there is still a large amount of photovoltaic power left after the enterprise consumes it during the day, and the enterprise has no additional electricity demand, the energy storage system will face a situation where there is no additional consumption space and will not bring additional gains to the photovoltaic system.
(3) If there is only a small amount of photovoltaic power left after the enterprise consumes it during the day, and it is mainly concentrated in the noon period, then the energy storage system may have the ability to consume this surplus power. At this time, it is necessary to consider the specific situation of the project and the benefits comprehensively. If necessary, the power user, the photovoltaic property owner and the energy storage construction party need to negotiate to find the best solution.
Industrial and commercial energy storage has the characteristics of large differences in project requirements, complex application environments, and diversified revenue models. In addition, the installation, commissioning, and operation of the project must be carried out within the enterprise and park, so the project requires high professionalism. In the construction process of the energy storage system, it is necessary to closely combine the actual project situation and carry out scientific and reasonable planning and design to ensure the smooth implementation and efficient operation of the project.
