Inspired by the Tesla Powerall


2KW Storage
120V/500W Output

  • 4x EnerAmp EA170 3.2V / 170AH LiFePO4 batteries
  • Overkill 4S 120A BMS + USB module
  • Renogy 700W Pure Sine Wave 12V Inverter
  • Progressive Dynamics 12V / 60A Li-ion Battery Charger
  • Raspberry Pi 4 with custom 12-bit ADC Hat
  • Xantrex PROwatt SW Auto Transfer Switch
  • Solid State Relay

Why I built this

I've had rooftop solar panels since 2014, and finally put in a Tesla Powerwall a year ago to store and conserve excess solar production.  The Powerwall app made me realize that even with the battery storage I was sending over 2kW of power back to the grid, and the compensation is of course pennies to the dollar.

So why not build a mini-Powerwall that plugs into an outlet and charges a battery when the Powerwall is full, and the Solar panels are producing more than what we are using?  That, and the opportunity to experiment with LiFePO4 batteries spurred this project.


I will post details of the build when I have more time.  Here's a sample visualization from my InfluxDB console.

In the winter months Lightning charges the battery from midnight to 3:00 AM when the rates are lowest, and powers my Dell R710 server (about 200W) from 3:00 PM to midnight.

© Venky Raju, All Rights Reserved.