Solar energy storage and battery options

Usually, your solar panel system is connected to the power grid. During times your solar panels produce more energy than your household consumes it can be fed back to the grid. In many places, you can earn money back on the meter. However, in many regions nowadays the grid cannot sustain the peak loads during shiny days. In those cases, no energy can be supplied back to the grid and you lose energy.

Hence, it might be interesting to install a solar energy storage system in your home. These batteries are still a significant investment but can save excess energy during peak hours. The stored energy can then be used during for example the night when your solar energy system is not generating any power. With the right sizing of both the solar battery banks and solar panel system, your house can become autonomous from the grid. At least during the summer months, this is a possibility. Nevertheless, do consider the payback time will be relatively long.

Specifications of a solar battery to consider

    1. Battery capacity: The amount of electricity you can store in a battery at Beginning of Life. This amount gradually reduces to a lower amount of electricity at End of Life.
    2. Power rating: The amount of electricity that can be provided to your home at each point in time.
      1. Peak power: The possible electricity maximum consumption surges.
      2. Continuous power: The amount of power supplied over a duration of time.
    3. Depth of Discharge (DoD): How much power needs to be maintained in the battery as a minimum.
    4. Round-trip efficiency: It indicates the percentage of electricity actually stored in the battery as supplied by your solar energy system.


Comparison of solar battery banks

There are different solar energy storage options available. In the table below an overview and comparison of the key characteristics of the most popular battery banks have been made.

Name Battery capacity [kWh] Continuous Power rating [kVa] Depth of Discharge Round-trip efficiency [%]  Type
Tesla Powerwall 2  13.5  5 .0    90 AC 
Enphase IQ Battery 10  10 3.84    89 AC
Generac PWRcell  9 4.5     96.5  DC
LG Chem RESU-10H  9.3 5.0    94.5  DC
BYD Battery-Box Premium HVS/HVM 22.1  22        
Duracell Energy Bank  13 5  90    AC
Moixa Smart Battery  9.6    85   AC
Nissan xStorage  10  6  90  90  AC
Samsung SDI All-in-one  3.6  5    84  AC
SolaX Battery System  6.5    95  95  
Varta Pulse 6  6.5      90  


The lifetime of solar batteries

Most modern solar batteries have a lifetime of 5 to 15 years. Note that the capacity and performance can significantly drop over time. Similar to your phone, electric car, or any other electronic device with a battery. There are methods to improve the battery life such as controlling the temperature and optimizing the number of discharge cycles.