How Much Battery Energy Storage Do You Need?

With the high cost of electricity and the increasingly serious environmental problems, more and more people store solar energy through solar batteries, and use solar energy to save a lot of electricity expenses. Maximize the role of solar energy.

Before buying, you may ask: How much power do I need for solar batteries in my home? Just like pure solar systems, the size of a rechargeable solar cell system depends on your unique energy needs and habits. When choosing the right battery storage solution for yourself, the following factors will play a key role.

  • Power consumption mode
  • Devices that need to be backed up
Household power consumption (Endurance time)

Generally speaking, it is difficult for us to accurately calculate the electricity consumption of each household, and we can only estimate it according to the general electricity consumption law of the household.

Typically, an energy storage battery has a power of about 10kWh:

  • If only used for backup power, doesn’t need too long endurance time, then a single solar battery is sufficient.
  • If you want to store excess solar energy during the day and use it at night to save electricity bills, you need to prepare 2-3 solar batteries.
  • If you want to be completely off the grid, you need a larger capacity solar system to support it. You may need 8-12 energy storage batteries for more storage space.

This suggestion is for reference only and needs to be selected according to the actual situation.

Devices that need to be backed up

The required battery capacity is determined by the service time, the number of devices and the power of connected devices. The power required by household equipment can be calculated by the power marked on the equipment and the actual use.

The calculation formula is:

Total Power=(S1W*T*N+S2W*T*N+……+SnW*T*N)

(S=Power of equipment, T=Duration, N=Nmber)

Therefore, if the battery is connected with more loads and the power supply time is longer, the power consumption speed of the battery will be faster. On the contrary, the fewer connected devices and the shorter service time, the slower the battery power consumption.

*For example my family has a refrigerator (200W * 1), 20 electric lights (10W * 20), a water heater (1000W * 1) and a microwave oven (800W * 1). It needs to be connected with solar cells as an emergency plan, which can be used for about 4 hours each time. 

According to the formula, the 10kWh solar battery I bought can meet the demand for backup power supply at home. (200W*1*4+10W*20*4+1000W*1*4+800W*1*4=8800Wh)

Specific proposals

Therefore, we investigated the electricity consumption of most households and concluded that there are usually three connection modes between households and solar cells: emergency backup, partial home backup and whole home backup. We calculated the approximate power required by the homeowner under three standby conditions in an hour, as shown in the figure below:


According to the above three dimensions and formulas, the approximate power consumption of the family can be calculated. In addition, you can also select the solar battery that perfectly fits your home through other data indicators of the electrical appliance.

  • Rated Power: refers to the amount of electricity that the battery can provide at a time and how many electrical appliances can be powered at a time. The greater the power, the more electrical appliances can be powered.
  • Round-trip efficiency: refers to the percentage of stored electrical energy that is later recovered or available for use. If you want to make full use of the power in the battery, please choose a battery system with high round-trip efficiency.
  • Cycle period: the ternary lithium battery commonly used in the past generally has only 400 cycles and service life of only 2 years. Compared with ternary lithium, LFP batteries can be cycled more than 4000 times and have a service life of up to 10 years. If you care about battery life, LFP batteries are the best choice.

However, whether solar batteries or other electrical appliances, there will be consumption, and the performance will change with continuous use. We still suggest that you buy solar cells with larger capacity to facilitate the expansion of capacity demand in the future.

*If this blog can’t solve your problem, please contact our team (, we will help you choose the most suitable solar battery for your home.

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