Inspired by the Tesla Powerall

Lightning

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.

Schematic

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.