Dry Batteries

Lead-acid battery technology has been around for over 100 years so it’s a very well-proven technology as well as being very safe and reliable when sized and installed correctly. For larger off-grid systems, lead-acid batteries are still one of the most trusted options and a correctly designed system can typically last 10-15 years or even longer (if shallow cycled and temperature controlled). Unlike lithium batteries, lead-acid battery banks do not have a specific cut-off point at a certain depth of discharge, so in an emergency they can continue to provide power until the voltage reaches the inverter cut-off, however, this will reduce battery life to some degree.


Deep cycle lead-acid batteries have been around for decades but more recently advanced, sealed, gel deep cycle batteries have taken service-free sealed lead-acid batteries further with up to 15 years of life. There are many well-established companies producing high-quality sealed tubular gel lead-acid (technically referred to as OPzV) and lead-carbon batteries.

Lithium Battery

The most obvious advantage of lithium batteries is their compact size and weight due to their extremely high energy density. Generally speaking, a lithium LFP battery is about 30% of the size and weight of an equivalent lead-acid battery, which is helped by the much higher depth-of-discharge available in a lithium battery. Lithium battery systems are generally made up of smaller, easy to handle modules of sizes from 2kWh to 4kWh which gives much more flexibility when sizing a system. This also enables additional capacity to be added if needed at a later stage.

When under load, the voltage drop of lithium is very low and will not generally fluctuate more than 1-2 volts* from nominal, even under high load (*48V). This is due to the much lower internal resistance compared to lead-acid batteries. The low resistance leads to the greatest advantage of lithium, which is the low losses during charging and discharging, resulting in very high round-trip efficiency.