At 24V, it produces about 8. The same panel gives you half the amperage at double the voltage. (Batterystuff) This is why most manufacturers recommend 24V or 48V systems for anything beyond small loads.
Temperature is the ultimate battery killer: For every 8°C (14°F) increase above 25°C, battery life can be reduced by up to 50%. Indoor installation in climate-controlled spaces can extend lifespan by 3-5 years compared to outdoor installations in hot climates.