Friday, February 8, 2013

LiFePO4 DIY ESS - Store your Surplus Energy at Home from Solar or Wind

An ESS is an Energy Storage System and its purpose is to store surplus energy, not used in your home, to re-use it later throughout the day or at night when solar generation is down;

It can also store energy from wind, or any other generation mean, even from the grid itself: you can help shave peaks and save money charging at night when electricity is cheap, and discharging during the day when it is expensive
My LiFePO4 DIY Battery ESS is an On-Grid Standalone System for people who already have solar or/and wind installed and would like to become even more grid independent

Using an additional inverter, it should be able to supply power inside your home - or office - only, in case of a power outage / black out

I have been working on this system for two years now and it is working fine with my new solar system, storing all the surplus during the day and giving it back whenever necessary, but mostly in the evening hours

The first 2 Kits are now available so you too can build one for your home and start shaving peaks using your own energy fully instead of selling it to the utility company

Make sure you go through the Pages on top to see : ESS Wiki, Components, Documentation, Kits, Power & Energy GraphsBuild History, More about the DIY ESS ... (just below the Blog Title/Header)

My DIY ESS in few Keywords:

- Low Cost
- Safe
- Simple
- Fully Automatic
- Plug & Play in a single 120V or 240V outlet
- Scalable in Capacity & Power - 5kWh + N * 5kWh & - 1,700W + N * 250W -
- Real Time Home & Online Monitoring
- Solar & Wind Installation Independent
- Battery Brand and Type Independent
- Off the shelf Quality Components : CALB CA Series LiFePO4 Cells, Tyco Kilovac Contactors, etc
- Small & Quiet & No bad Smell (can be used in an apartment)
- Transparent Battery Management (BMS): you know what it does, nothing is hidden like in EVs or other battery storage systems; It is very simple, efficient and safe

With CALB CA180FI LiFePO4 Cells, simply the best on the market today, used in Electric Car Conversions !

Online Power Monitoring (with Wattson Anywhere based on EnergyHive)
Power graph (click)

Energy graph

The Price should be - only - 3,000 Euros for a 5kWh 1.8kW ESS

A Kit is & will be available with different levels of integration and costs:

Kit #1
- Arduino Leonardo board, flashed with my program
- ESS Building step by step Documentation
- List of Components & Adresses to get the parts
- User Manual
Price: 149 EUR only

Kit #2
- Kit #1
- All the components to build the Control Board
Price: 649 EUR

  - Modified Wattson (coming soon)
  - Crimped Cables & Lugs Set (coming soon)

Kit #3
- Kit #2
- 8 Grid Tie Inverters 110-220V
- 6 Chargers 110-220B
Price: Tbd

Kit #4 - Full Kit -
- Kit #3
- 8 LifePO4 CALB CA180FI cells, bottom balanced by me
Price: Tbd


  1. Bonjour Christophe,

    Very interesting stuff you are doing. I wish I understood it. :-)

    I'm contemplating/planning on building a 5 kWp solar panel array this summer, with a 9600 Wh LiFeYPO battery pack (60% DOD = 5760 Wh). Right now I'm trying to understand the system behind it (inverter, controller, battery management system, etc), but I can't seem to find much info. Or maybe I'm not looking hard enough.

    There are some plug&play products out there, of which the PowerRouter looks interesting, but expensive at € 4500.

    I'll try and keep an eye on your project.



    1. This comment has been removed by the author.

    2. Hi Neven,

      Thanks for your comment; You probably came to the right place if you want to understand some of the basics that I explain along my project started more than a year ago now.


    3. Go to for more

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  3. Hello Christophe,

    I am very interested in the DIY ESS.
    In my house there are two PV solar systems and I draw now on the import and export.

    This Linux-Daemon can provides the "going power to the grid" as web service or any other service.

    A Smart Electric Drive car completes my equipment.

    Is it possible to use your ESS with my infrastructure? You already know, wass there will be the first kit?

    (The Power Management System (PMS) - the heart of the ESS - only + the documentation to integrate all the other components)

    Best Regards,


  4. Hi Nico,

    Thanks for your message, I am happy to see that some people who already have solar are interested in my Storage Solution !

    My DIY ESS can works with any installation, because it is based on its own Wattson energy monitor (to detect used power, generated power and net power) to trigger charge or generation (Wattson is easy to install)

    I am finishing my first Control Board (= PMS (Power Management System) ) and will offer, after some more testing shared on my blog, a Kit made of the Arduino Leonardo board, flashed with my program, and a very detailled step by step documentation to build your own control board)

    I will keep you posted on this



  5. Hello,

    I have another idea. To optimize the inverter side, you could use an old SMA inverter, f.e. SMA SB2100TL or SB3000. These inverters can be controlled via RS485 interface and the Yasdi library.


    Here you can find a little "C" tutorial in german:

    On hardware you need for 2.1kW:

    - SMA SB2100TL (ebay 300€)
    - original Piggy Back (internal interface rs485,
    - USB RS485 adapter (ebay 20€)

    Than you can control the output power with a telegram in RS485 bus (command: CMD_PDELIMIT)

    Here the datasheet of the protocol

    Your charger control site is very good. A CAN controlled charger with 100 to 3000W is very very expensive. The selectable 90W levels are a brilliant idea, and especially low price!!! Great!

  6. Hi Nico,

    This looks like a good idea ! Actually, I already though of a controller feeding variable DC to a big grid tie inverter (2000W or more), but could not find any beefy enough device to do so ...
    So I use several small SUN250G GTIs which do the job fine; They all give out 220W at this voltage (25-26V) and the first one is a modified one (different MOSFETs) that gives only 70W, and is used to adjust power output with "more tuning": 7 x 220 + 70 = 1610W for now

    Anyways I will look into your advice because it sounds promising ...



    1. Hi Nico,

      For a week I looked into your idea and found very interesting work done on communication with Arduino board equiped with Bluetooth shield and SMA inverters ... if I could connect, send the CMD_PDELIMIT command and raise or lower the output power, that would be great ! But looking at SMA inverters technical data, I realized that I completely forgot that the minimum voltage they require is ... around 120V ! which is not at all what I have here in my battery pack :-(

    2. This comment has been removed by the author.

  7. (Re-writing of May 3, 2013 comment)
    Hi Nico,

    It is working very well now with this New ESC - Electronic Speed Controller - added last sunday on GTI #1: the power output by the ESS is now very close the home usage
    It is good step forward in précision !

  8. I look forward to the completion of all your kits for sale. I hope you design your kits for people who are new and do not know about electrical engineering. Please ensure paypal services are available for business transaction. Thanks.

  9. Hi NewTech,
    Yes my Kit is something that can be mounted by a someone who can use wrench, soldering iron, screwdriver, drill, know basics on AC power, etc and the Buidling documentation is a very detailed step by step one, with many pictures.

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