Solar energy can be stored in a lithium battery or LiFePO4 battery for hours to several days, depending on battery type and usage. In this article, we'll offer some suggestions on how to accomplish safe storage of lithium batteries. You should avoid storing these batteries fully drained or fully charged for long periods, as this. . Imagine setting up your solar system only to find that your batteries aren't functioning as they should. Proper storage not only protects your investment but also ensures you get the most out of your renewable energy setup.