Storage (Batteries)
We only make use of Lithium-Ion batteries for various reasons. Lithium Iron Phosphate batteries might seem expensive when compared to lead acid batteries, but this is not true.
A proper scenario comparison will reveal that the purchase costs are very similar and any marginal premium for a LiFePO4 battery is more than compensated for by longer life and a very high efficiency. The high efficiency means that far less energy is wasted and that the solar array can be 30% smaller to achieve the same results.
In general – because of the high DOD (Depth Of Discharge) capability and high efficiency the ampere hour rating of a LiFePO4 battery need only be 35% of a lead acid battery to give the same useful output – this is important when comparing costs between the two technologies.
UPS systems are notorious for the short life span of the typical lead acid batteries they use, especially if the batteries are kept in a high temperature environment.
LiFeP04 cells are much less sensitive to high temperatures and can happily operate up to 45°C with negligible drop in life span or performance. Lithium-Ion is regularly chosen for new installations or as a suitable replacement for lead-acid batteries which have reached the end of their life in a solar PV storage system.
Reasons for Lithium-Ion being selected include:
• Lighter weight.
• Higher efficiency.
• Greater depth of discharge.
• Higher cycle life.
• Better maintained voltage during the discharge cycle.
• Lower lifetime costs.
• Lower impact on the environment.
• Longer warranty available.