What does this tool do? Who is it for?
We are a research team exploring the viability of repurposing used EV batteries for home energy storage. This calculator allows solar homeowners to compare the cost savings and sustainability impact of several new energy storage systems (ESS) against several used, hypothetical ESS product options.
Who & What
The data provided by this tool can be used to help you make a more informed decision about which ESS product option, if any, makes most sense for your home, and by our team to better understand whether repurposed EV batteries could serve as a cost effective storage solution for solar owners.
Why
The calculator makes several key assumptions and simplifications to make it relevant to as many users as possible - see the Methodology section below for more details on the abilities and limitations of this tool. We are continually adding more product options and updating the calculator to make it as accurate and helpful as possible.
How
Energy storage savings calculator
Your Setup
Please enter a 5 digit zipcode.
New ESS Model
Used ESS Model
How'd we get these numbers?
Let's dive into the nitty gritty.
Start
First, we estimate your energy rates and average daily consumption based on the size and location of your home. We take into account factors like solar production based on where you live, net metering, and the average energy prices in your state.​​
Calculate Daily Energy Savings
Estimate Monthly Bill & Annual Savings
We then combine your calculated energy profile with the specs of the products you selected to calculate your energy costs for each option over a single representative day. The hourly solar production data and energy rates found in the first step are combined with a standard hourly load profile for a home of your size to estimate your net energy production and consumption over the course of one day.
These single day costs are then multiplied to calculate your monthly bill and annual savings for each product option. There are a few key assumptions we make in this section that introduce error and uncertainty into the data. These assumptions make the calculation simpler and applicable to a greater number of solar homeowners, but it is worth understanding these assumptions and the limits they place on the accuracy of the data.
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Your solar production and energy load are consistent throughout the entire year - we use a simple multiplier to scale from the single representative day in the previous section to your annual total. In reality, both solar production and load fluctuate day-to-day and throughout the year.
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The battery product options you selected retain the same capacity and efficiency throughout their lifetimes. In reality, the capacity and efficiency of both the new and used products will decline to some degree throughout the product lifetime.​
Calculate ROI
From the savings values established in the previous step, along with the initial cost and expected lifetime of the products you selected, we project how long it will take you to pay back your initial investment. We also calculate your net present value (NPV) savings, which calculates your total earnings but takes into account expected product lifetime and a derating factor to offset for risk and upfront cost. Finally, we estimate your return on investment (ROI), which is the ratio of your NPV savings to your initial investment.
Estimate Resource Savings
In our last step, we estimate the lithium (Li), cobalt (Co) extraction, and carbon dioxide (CO2) emissions that would be prevented if you utilized the used energy storage product. We assume a fixed number kilograms of Li, Co, CO2 saved per kWh stored to determine the resource savings over the lifetime of the product.
About Us
ReVolt Renewables is a research team in the Front Range area of Colorado exploring the idea of transforming used EV batteries into a reliable, low-cost alternative to traditional home energy storage systems. We created this calculator for two reasons:
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To provide solar homeowners with a tool to compare the cost savings and sustainability impact of new energy storage systems (ESS) against used, hypothetical ESS product options.
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To better understand the interests and priorities of solar homeowners like yourself so we can develop ESS solutions that fit your budget, needs, and lifestyle.
Let's get in touch
We have exciting prototypes and test results in the works, and we'd love to share them with you. Tell us about your level of interest and what you'd like to hear, and we'll share updates with you as soon as they arrive!
