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Battery & storage
Depth of discharge impact calculator
Enter your battery's nameplate capacity and compare usable energy across different depth of discharge settings side by side.
How it works
Three steps to comparing depth of discharge
Step 1
Enter your battery's nameplate rating
This is the number printed on the spec sheet, before any real-world losses are applied, the same starting figure used in the usable vs nameplate capacity tool.
Step 2
Compare across the common range
See exactly how many kWh separate an 80% setting from a 95% or 100% setting on your specific battery.
Step 3
Layer in efficiency losses separately
This tool isolates depth of discharge alone. The usable vs nameplate calculator combines it with round trip efficiency for the full real-world figure.
Understanding depth of discharge
What depth of discharge actually controls
Depth of discharge is the percentage of a battery's rated capacity that can be safely used before recharging, set either by the battery chemistry's physical limits or by a manufacturer's software-enforced reserve to protect long-term health. Modern lithium home batteries commonly support 90 to 100% depth of discharge, a significant improvement over older lead-acid battery technology, which often limited usable capacity to 50% or less to avoid damaging the cells, a chemistry-driven gap NREL's Annual Technology Baseline reflects in its residential lithium-ion assumptions.
Why some systems deliberately use a lower setting
Even when a battery's chemistry supports a higher depth of discharge, some manufacturers or installers configure a more conservative default setting specifically to reduce stress on the battery cells and extend total lifespan measured in charge cycles. This trades some usable capacity today for a longer-lasting battery overall, a tradeoff described in the Department of Energy's energy storage program, worth understanding rather than assuming more available capacity is always better. The reserve percentage setting tool covers this adjustable range in day-to-day use, separate from backup sizing.
Depth of discharge versus degradation
These are related but distinct concepts. Depth of discharge is a setting applied to every charge cycle, determining how much of the rated capacity gets used, while degradation is the gradual and largely irreversible loss of total capacity that happens over years of use regardless of depth of discharge setting. A battery with a conservative depth of discharge setting may still degrade over time, just from a smaller starting baseline of cycled capacity. The round trip efficiency calculator covers a separate factor that also affects usable energy on top of both of these. Depth of discharge also shapes how fast a pack wears out at a given charge rate, which the charge rate versus lifespan tradeoff tool compares directly.
What to do with this number next
Once you understand how depth of discharge affects your specific battery, the usable vs nameplate capacity calculator combines it with efficiency losses for a complete real-world usable energy figure, which feeds directly into the battery storage size calculator. A battery is only useful if the inverter can carry your loads. The hybrid inverter sizing calculator in our Inverters & Equipment section can help you size it for the biggest appliance you run.
Questions
Frequently asked
A 13.5 kWh battery delivers 10.8 kWh usable at 80% depth of discharge, 12.15 kWh at 90%, and 12.82 kWh at 95%. The difference between 80% and 95% depth of discharge on this battery is about 2 kWh, roughly 15% of the total nameplate rating.
A lower depth of discharge setting reduces stress on the battery cells, which can extend the battery's total lifespan measured in charge cycles. Some manufacturers or installers set a more conservative depth of discharge by default specifically to protect long-term battery health, trading some usable capacity for longevity.
No, they're related but different concepts. Depth of discharge is a setting that determines how much of the rated capacity you use each cycle, while degradation is the gradual, permanent loss of total capacity over years of use regardless of depth of discharge setting.
Many battery systems allow adjusting the depth of discharge or reserve percentage through a companion app after installation, though the safe range is set by the manufacturer and can't typically be exceeded. The battery reserve percentage setting tool covers this adjustable range in more detail.