Last week there were four days of overcast skies and two days of rain. This is the type of weather patterns that make most people living off the grid want to have a backup generator when their battery charge is gone. In our neighborhood on the East Cape, you could hear the generators come on after the first day of completely grey skies.

This was the situation that we faced regularly with our old, sealed lead-acid battery storage system. Having changed to lithium-ion batteries (Blue Ion for the main house and Simpliphi for the casita), we wondered how different it would be from the past.

Our lithium-ion batteries charge on GLARE alone. As long as there is a glare coming through the clouds, these batteries will charge. The full charge on our 48V system is 55.2 volts. One day, we reached 54V and during the four days, we charged to 53.6 V on the other days. Consequently, we never had to start the generator. This is an AMAZING benefit of lithium-ion batteries. They start to charge immediately as long as some light is hitting the panels, without a need to go through the bulk, charge and float process required by lead acid batteries.

While lithium-ion batteries may be more expensive than lead acid or sealed lead-acid batteries, they last longer, have a longer warranty and are dramatically more efficient. We could not be happier.