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# > Energy Storage Battery Savings Calculator

Set up Costs
If not included in system cost.
If not included in system cost.
Note: If installing solar at the same time, put the total system cost here and in the Energy Cost Saving section put just the peak rate charge details; we are assuming that you have sufficient solar to charge your batteries full each day if required.
System Information

Note: This is the number of charge/discharge cycles the battery can perform before it wears out. For instance it is reckoned the Telsa Powerwall is rated for 1700 cycles, whereas the RedFlow 10Kw system is rated as good for 3000.

Note: Efficiency is multiple of all energy conversion steps in the system, i.e. battery efficiency and inverter efficiency, i.e. assuming an efficiency of 95% for both, the total efficiency would be 90.25%. Typically for Lithium Ion and flow battery based systems is 80%.
Energy Cost Savings
This is the difference in price between the cost of power to charge the battery (i.e. cheap rate) compared to the cost of power when the battery is to be discharged (i.e. peek rate), e.g Given a cheap rate cost of \$0.02 and a peek rate cost of \$0.30 the saving would be \$0.28. If you are sourcing power from a solar system, just put the peak rate cost here.
This is the total energy you expect to offset during the peak period - you should be able to get this figure straight off your quarterly bill.
Bank Returns
Typical rate of return is around 2.5%

With this calculator you can work out how long an investment in an energy storage time shifting system for your home would take to be paid back in full. Such systems typically charge a battery during the off peak period and then discharge during the peak period, so saving you the difference in price between peak and off peak. As such you need to repeat this cycle a number of times to get back the cost of the investment in the system, this calculator will help you work out when that will occur.

This is useful for systems like the Tesla Powerwall to work out the base minimal expected repayment period.