If you need 10 kWh daily, select a battery with a 12 kWh capacity, allowing for 80% depth of discharge. Grid-connected systems often need 1-3 lithium-ion batteries. Next, factor in your. . To determine the battery size for solar, first calculate your daily energy consumption. By inputting specific details about your energy consumption, this calculator provides tailored insights into the solar. . Finding the right battery size ensures you maximize your solar energy storage, allowing you to use that clean energy even when the sun isn't shining. Learn the difference between Group 24, 27, and 31 batteries — and how to match them with solar panels for efficient off-grid power. . As you can see, properly "sizing your battery" is the most critical step to making your investment as cost-effective as possible. Before we jump to the calculator, let's get to know the four key pieces of information you'll need to have in mind. How Much Power You Want to Store (kWh/day) Just. . In general the system should be big enough to supply all your energy needs for a few cloudy days but still small enough to be charged by your solar panels. Here are the steps to sizing your system. Related Articles: Solar battery Storage Systems: If You Can't Tell Your AGM from Your Gel Off-Grid. .