Calculate battery costs, backup capacity, and savings from storing your solar energy
This calculator estimates the total cost, savings, and payback period for adding battery storage to your solar system. It considers multiple value streams:
Charge your battery during off-peak hours (or from solar during the day), then discharge during expensive peak hours (typically 4-9pm). This avoids peak rates that are 15-30 cents/kWh higher than off-peak.
Example: Store 10 kWh at 12 cents/kWh, use at 35 cents/kWh = $2.30 saved daily = $840/year
Without batteries, excess solar goes to the grid at low buyback rates (often 50-75% of retail). Batteries store this excess to use later, capturing full retail value.
Example: 5 kWh/day excess solar × $0.15 rate difference × 365 days = $274/year saved
Peace of mind during outages. Hard to quantify but worth $500-1,000/year depending on outage frequency and your needs (medical equipment, work from home, food spoilage, etc.).
Prices include installation but before 30% federal tax credit
Price trend: Battery costs dropped 50% from 2020 to 2024 and continue falling 10-15% annually. If ROI is marginal now, waiting 1-2 years could significantly improve economics.
In these cases, batteries may still provide value through backup power and energy independence, but purely financial ROI is weak. Consider waiting for prices to drop further.
Yes! As of 2023, solar batteries qualify for the 30% federal tax credit when paired with solar panels. The battery must be charged by your solar system at least 75% of the time. This significantly improves battery economics - a $12,000 battery effectively costs $8,400 after the credit.
Most lithium-ion solar batteries are warrantied for 10 years or 10,000 cycles, whichever comes first. With daily cycling (365 cycles/year), expect 10-15 years of useful life. Batteries degrade gradually - after 10 years, capacity is typically 70-80% of original. Tesla Powerwall and LG batteries have strong track records with minimal degradation.
It depends on battery size and your loads. A 10 kWh battery (like Powerwall 2) powers essential loads (fridge, lights, internet, TV) for 12-24 hours. A 13.5 kWh battery can power most appliances (but not AC or electric heat) for 8-16 hours. For whole-home backup including AC, consider 20-27 kWh (two batteries). Most homeowners start with one battery for essentials and add more later if needed.
Yes! Most modern batteries work with existing solar systems through AC-coupling. Tesla Powerwall and Enphase IQ batteries retrofit easily to any solar system. You may need a new inverter or gateway device (typically $1,000-2,000). DC-coupled batteries (connected directly to solar panels) require compatible inverters and are typically installed with new solar systems. Retrofitting batteries still qualifies for the 30% federal tax credit.
AC-coupled batteries (Tesla Powerwall, Enphase) connect to your home's AC electrical panel. Easier to retrofit to existing solar, works with any solar inverter, slightly less efficient (90-92%). DC-coupled batteries connect directly to solar panels through a hybrid inverter. More efficient (95-97%), cheaper installation with new solar, but requires compatible hybrid inverter. For retrofits, AC-coupled is usually easier. For new installs, DC-coupled saves $1,000-2,000.
Explore our comprehensive guide to solar battery storage, including brand comparisons, sizing guidance, and installation tips.
Read Battery Storage Guide