Information about battery storage
Currently (2025), lithium-ion batteries remain the dominant and most recommended technology for solar power storage in residential and most commercial applications. Within the lithium-ion family, lithium iron phosphate (LFP) batteries in particular have emerged as favorites, offering an excellent balance of safety, longevity, and efficiency.
WHY LITHIUM-ION (especially LFP) ARE THE BEST BATTERIES:
* High efficiency:
Lithium-ion batteries achieve system efficiencies of over 90% (often 95% or more).
* High energy density:
They can store a lot of energy in a relatively small space, saving space.
* Deep depth of discharge (DoD):
They allow discharge to reach 100% of their capacity without significantly affecting their service life. This means that almost all of the stored energy is usable.
* Long cycle life/high cycle count:
Modern LFP batteries achieve 6,000 to 10,000 charge cycles or more, corresponding to a service life of 15 to 20 years or more.
* Low self-discharge:
They lose very little energy when not in use.
* Fast charge and discharge times:
They can absorb and release energy quickly.
* Safety (especially LFP):
Lithium iron phosphate batteries are considered particularly safe because they are more thermally stable and, if damaged, are less likely to catch fire or explode than other lithium-ion chemistries (e.g., NMC). They are also non-toxic.
Important factors when choosing a power storage system:
* Capacity (kWh):
How much energy can the battery store? This depends on the household's electricity consumption. A common rule of thumb is that the storage system should be approximately 1 to 1.5 times the annual electricity consumption per 1,000 kWh.
* Power (kW):
How quickly can the battery be charged and discharged?
* Efficiency (Round-Trip Efficiency):
The percentage of energy charged into the battery that can be withdrawn. Higher values are better.
* Depth of Discharge (DoD):
The percentage of the battery's capacity that can be used.
* Lifespan (number of cycles or years):
How many times can the battery be charged and discharged before its capacity decreases significantly.
* Warranty:
Manufacturer's product and performance warranty.
* Modularity and Scalability:
The ability to expand the storage capacity as needed.
* Compatibility:
Does the storage system fit with the existing or planned inverter and energy management system? Many manufacturers offer complete systems.
* Value for money:
The total cost over the lifetime of the battery.
In summary, lithium iron phosphate (LFP) batteries are currently the best choice for most home solar storage systems due to their balanced properties in terms of efficiency, longevity, and safety. Manufacturers such as BYD, Sungrow, RCT Power, and Tesla are leading the market.