The battery is the heart of any off-grid power system. Treat them well and they will reward you with a long life.
Lead acid batteries continue to dominate the off-grid market mainly due to cost, predictable performance and high reliability. However, new Lead Carbon technologies offer the promise of higher cycle life and less sulfation.
The longest lasting lead-acid batteries are 2V cells, which have a tubular plate. These can last up to 20 years. The next best option is to choose a 6V block, which tend to have a heavier construction than most 12V blocks.
Gel or AGM batteries are more resistant to deep discharges, as well as being sealed and maintenance free. This makes them more suited to remote sites and safer to handle.