Skip to content

Solar Battery Size Calculator

Calculate the battery storage capacity you need for your solar energy system.

Required Capacity (kWh)
18
Powerwalls Needed
2
Estimated Cost
$9,000
Daily Excess Solar (kWh)
0

Solar Battery Size Calculator: How Much Storage Do You Need?

A solar battery storage system lets you store excess solar energy for use at night or during power outages. Properly sizing your battery ensures you maximize self-consumption and minimize grid dependence.

This calculator estimates the battery capacity you need based on your daily energy usage, desired backup hours, and solar production. It also estimates the number of Tesla Powerwall equivalents and total cost.

Battery prices have dropped significantly, from $1,000+/kWh in 2015 to $400-$600/kWh today. With the 30% federal tax credit, battery storage is increasingly affordable for homeowners.

For related tools, see our solar panel ROI calculator and solar savings calculator.

FAQ

Share

FAQ

How much battery storage do I need?+
For whole-home backup, typically 10-20 kWh (1-2 Powerwalls). For essentials-only backup, 5-10 kWh may suffice.
How long do solar batteries last?+
Most lithium-ion batteries last 10-15 years with a warranty of 10 years or 70% capacity retention.
Can I go completely off-grid?+
Technically yes, but it requires significant oversizing of both solar and battery systems, making it expensive.
Are solar batteries worth the investment?+
In areas with high electricity rates, frequent outages, or no net metering, batteries offer good value. The 30% tax credit improves ROI significantly.

Most Popular Tools