[Latest] How to configure a set of home energy storage devices?

As the world becomes increasingly dependent on technology, power outages can be a major inconvenience. A home battery backup is an effective solution to ensure you never lose power under any circumstances. In this article, we'll discuss the benefits of a home backup battery and how to choose the right one for your needs.

Home battery storage devices are designed to store electrical energy and use it when needed – also known as electrical energy storage products or “battery energy storage system” (BESS). The core component of home storage is rechargeable batteries, usually lithium-ion batteries or lead-acid batteries. Acid battery. The other components are inverters, which can intelligently control the charging and discharging control system.

Part 1. The benefits of a backup battery

1.1 Ensuring an uninterruptible power supply:

Using a backup battery ensures that your devices and devices remain powered even during power outages. This is particularly important for critical systems such as medical devices, security systems and communications devices.

1.2 Overvoltage protection:

A backup battery can also protect your devices from power surges that can damage sensitive electronics. The battery acts as a buffer, absorbing the excess voltage and preventing it from reaching your devices.

1.3 Comfort and Portable:

Backup batteries are usually portable and can be easily taken anywhere. This makes them a convenient option for powering devices on the go, such as during camping trips, long commutes, or outdoor events.

1.4 Save money:

In some cases, a backup battery can save you money in the long run. For example, if you have a solar-powered backup battery, you can reduce your utility bills by using free, renewable energy to power your devices.

1.5 Environmentally friendly:

Using a backup battery can also be an environmentally friendly option as it reduces your reliance on non-renewable energy sources and helps reduce your carbon footprint.

Part 2. What you need to know before preparing a battery storage system for your home

In the household energy storage system, the main components are solar panels, energy storage machines and batteries. The form shown in the image above is used to set up the energy storage in the garage for use by our electric vehicles.

Energy storage systems are divided into single-phase and three-phase systems. The image below is a simple diagram of an energy storage system. In addition to the three main components, it also includes electricity meters, household loads, etc. Whether single-phase or three-phase, there are appropriate solutions.

2.1 Single-phase and three-phase electricity

Electric power is the speed at which electrical energy is transmitted or used. It is usually expressed in watts (W) or kilowatts (kW). Single-phase and three-phase electricity refer to the different methods of distributing electrical energy.

Single-phase current is a single alternating current (AC) waveform that flows through a single conductor. It is often used in homes and small businesses where the need for electrical energy is low. Single-phase current is also called single-phase current.

Three-phase power, on the other hand, is a type of polyphase power that uses three AC waveforms that are 120 degrees out of phase with each other. It is widely used in industrial and commercial applications where the demand for electrical energy is high. Three-phase power is also more efficient than single-phase power because it allows for more balanced load distribution.

In summary, single-phase power is a single AC waveform that flows through a single conductor, while three-phase power is a type of polyphase power that uses three AC waveforms that are 120 degrees out of phase with each other.

2.2 energy storage batteries (LiFePO4 vs. Lead-acid battery)

The use of lithium batteries is recommended as a battery. Lithium batteries are made of lithium metal or lithium alloy as the negative electrode material and use non-aqueous electrolyte solutions. They have many advantages such as high energy, long lifespan and light weight. They are commonly used in energy storage systems such as hydro, thermal, wind and solar power plants, etc. used

Battery type	Lead-acid battery	LiFePO4 battery
Energy density	Low	3 times higher than LA
Internal resistance and self-discharge	High	Low
Energy discharge rate	30%-40%	80%-90%
Temperature tolerance	Low	High
Security	Low (presence of toxic substances)	Excellent (no risk of fire/explosion)
Lifespan	400 (usually lasts between 3 and 5 years)	2000 (up to 10 years or more)

Self-discharge comparison between LiFePO4 and LA batteries

Temperature tolerance comparison between LiFePO4 and LA battery

LFP example products:

LFP-100: Timeusb 12V 100Ah per LiFePO4 battery

LFP-50: Timeusb 12V LiFePO4 50Ah per battery

2.3 working modes

Mode 1. Load consumption priority: PV – battery – grid

1. The electricity generated by photovoltaics is given priority to the load, the excess electricity is stored in the battery, and the excess electricity is sold to the grid; If the PV is insufficient, the battery will be discharged for use by the load.
2. If the power grid fails, the load at the grid-connected output end cannot work; However, the load at the off-grid output end can work normally and be powered by PV and battery.

Mode 2. Saving mode settings

Note: In general mode, the mains does not charge the battery. When economy mode is set, you can set the period for charging and discharging the battery.

The main function of economic mode is to smooth peaks and fill valleys. It can use the grid's power to charge the battery during the evening low and use it for the load during the day's peak. This mode can reduce the difference between peaks and valleys, thereby saving electricity costs.

Part 3. How to configure battery capacity?

When choosing the battery, the load should be taken into account, regardless of whether it is used daily or as a backup. If the battery capacity is too large, waste occurs, and if the stored electricity is used up, the battery will not be fully charged.

So what is the quickest and most direct way to select the best solution for battery capacity in the household energy storage scenario?

Currently, most households use energy storage to adjust the use of grid power, which we commonly refer to as grid-tied energy storage. For grid-connected energy storage, the main purposes generally fall into three categories: photovoltaic self-use (higher electricity costs or no subsidies), peak and valley electricity prices, and emergency power (grid instability or important loads).

3.1 Increase the personal use rate of photovoltaics

The main purpose of this scenario is to install a photovoltaic energy storage system to reduce electricity bills when the electricity price is high or the grid-connected photovoltaic subsidy is low (no subsidy), so that the remaining power of the photovoltaic system is used except during the day Available use can be stored and stored for night use.

We divide household electricity consumption into daytime electricity consumption (periods with high photovoltaic electricity generation) and nighttime electricity consumption (periods with low or no photovoltaic electricity generation). According to the above purpose, the ideal condition should be that the electricity generated by photovoltaics can meet the daytime electricity consumption, and after storage, it can just barely meet the nighttime electricity consumption.

That is, the effective capacity of the battery should be approximately equal to the photovoltaic power generation minus the daily power consumption. But that is just an ideal situation. In addition, in order to avoid battery capacity redundancy (to avoid depletion at night), we need to ensure that the effective power of the battery does not exceed the power consumption at night.

This requires a more detailed understanding of the laws of household electricity consumption and knowledge of the rules for determining the priority level of power supply in the energy storage system.

A family is equipped with a 5 kW photovoltaic system, the daily electricity generation is around 17.5 kWh. The average daily electricity consumption of a household is about 20 kWh, of which the average daily electricity consumption is 5 kWh during the day and 15 kWh at night. Then the effective power of the battery should be approximately 17.5-5 = 12.5 kWh, and this also meets the condition of not exceeding the nighttime power consumption (12.5 kWh ≤ 15 kWh). Therefore, the best battery available for this family is 12.5 kWh.

3.2 Prune peaks and fill valleys to reduce utility bills

The main purpose of this scenario is to charge the battery during the low electricity price during the day and discharge the battery at night during the peak electricity price, thereby reducing the overall electricity bill.

We divide household electricity consumption into daytime electricity consumption (period of low electricity prices) and nighttime electricity consumption (period of highest electricity prices). In this scenario, the ideal situation is to “use the remaining power after the photovoltaic power supply to the load and the grid to charge the battery during the day, and the battery power is just enough to be used at night (when the price of electricity increases)." Sharpen)".

This means that the effective capacity of the battery is approximately equal to the family's electricity consumption at night. However, the battery capacity calculated based on nightly power consumption is only a maximum demand value.

When it comes to battery costs, it is fundamentally necessary to comprehensively consider the three levels of photovoltaic system capacity, battery investment and electricity price savings in order to determine an optimal ratio. At the same time, it must be ensured that the battery discharge time is not longer than the nightly power consumption.

A family with a 5 kW photovoltaic system installed has an average daily electricity consumption of about 20 kWh, and at night (assuming that the electricity price peak and lowest times are from 5:00 p.m. to 10:00 p.m. for a total 5 hours), the electricity consumption is 15 kWh. Assuming that according to the calculation, the effective capacity of the battery covers 2/3 of the family's nightly electricity consumption, this is the best investment return point.

Then the effective power of the battery should be approximately 15*2/3=10kWh. At this point, the battery capacity is about 10 kWh/5 kW = 2 hours, which is less than or equal to 5 hours of nighttime power consumption. Therefore, the best battery available for this family is 10 kWh.

3.3 As a backup power source in areas with unstable power grids

When the energy storage system is used as a backup power source, it is mainly used in areas with unstable power grids or high load situations. For example, basic lighting, refrigerators, desktop computers, etc. the family; the data room of the industrial area, the important equipment of the industrial area, the lighting and ventilation equipment of the breeding area, etc.

When designing battery capacity with backup power as the primary purpose, the primary consideration is that the battery alone can supply the power required by the important load when the battery is disconnected from the grid for the longest period of time (the longest expected power outage time). including the need to take into account the case of no PV at night.

In this scenario, the battery capacity is relatively easy to calculate. To first determine battery capacity, all you need to do is list all major loads and calculate the power consumption of all loads during the longest power outage.

Taking an important commercial site as an example, the important load is 10 cabinets in the data center, and the power consumption of each cabinet is 3 kW. The expected maximum downtime is approximately 4 hours. According to calculations, the effective battery capacity of this project should be 10*3kW*4h=120kWh. Therefore, the effective battery power for this industrial and commercial project is best to be 120 kWh.

The above three situations represent the most common requirements for installing grid-connected energy storage systems, and there are rules to follow when selecting battery capacity. However, in practical applications, two or more requirements may overlap, requiring detailed analysis of the requirements and ultimately determining the most suitable capacity of the battery.

In addition, we mentioned the effective performance of the battery in the above analysis. However, the actual selection of the battery also needs to consider the surge load of the load, the DOD (depth of discharge) of the battery, the loss system efficiency, the performance of the energy storage device and the expected return on investment. And many other situations.

Therefore, when selecting battery capacity, it is necessary to consider the performance of the entire family or usage scenarios as a whole system, and it is also particularly important to select the best equipment and system integration suppliers.

Frequently asked questions about energy storage for private households

1. Does an accumulator work without solar modules?

A storage battery can also function without PV modules, but this is only possible if an alternative charging method is available.

2. Can you add solar panels to your battery later?

If your backup battery for your home or portable power station can be charged with solar energy, you can add solar panels at a later date. These power plants can usually be purchased individually or as a package with photovoltaic (PV) modules. Additionally, you can use different types of panels for different scenarios by combining rigid PV panels on your roof with portable panels for outdoor activities. Due to the universal design, all of these panels can be connected to the same battery.

Conclusion

A backup battery is a worthwhile investment for any homeowner who wants to ensure a reliable power supply even in the event of a power outage. Given the benefits of saving money, reducing your carbon footprint, and providing a reliable power source, it's no wonder home backup batteries are becoming increasingly popular.

This article introduces various ways to prepare your own power storage system. I hope it would help you.