Blog - LiFePO4

Micro Energy Storage Setup

NOTE: this is a grid-tied system setup with an energy back up to the batteries. This system is grid-tied only. The micro-inverter works only when the grid is present. If the grid is down, the system does not work. It is NOT an off-grid system.

NOTE (2019 update): the illustrational picture shows a system we made in 2013 with some components which are no longer available (like the 36V regulator). We've nevertheless updated the list of components below so you can make the same system with components which are up to date and available in our e-shop.

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A practical realization of a small size energy storage solution with 3.2 kWh of energy capacity with 230V/230W AC grid-tied power output. The basic concept of energy storage with easy expansion. The purpose of the installation is to store the energy in the batteries and release the energy slowly when needed.

Components description of the complete setup

* Lithium Battery Pack 24V
The battery pack of 24V/90Ah made of 2 finely balanced 12V/90Ah LFP batteries. The nominal capacity is 2,16 KWh of energy. There can be more batteries easily added to increase the capacity of the storage.
https://www.ev-power.eu/LiFeYPO4-batteries-12V-1-1/Lithium-Battery-12V-90Ah-WB-LP12V90AH.html (USD 460 per unit, total USD 920 for 2 pcs)

* Solar charge regulator 
The solar charge regulator protects the batteries against deep discharge and against overcharge. The charger chooses the right voltage level automatically: 24V in this case.
https://www.ev-power.eu/mppt-pwm/Solar-PWM-Controller-12-24-V-20A-Input-50V-USB-VS2024AU.html (USD 35)

* DC/AC Grid-tied Inverter
The Inverter generates the energy to feed to the local 230V grid. It includes a limiter to prevent an overflow to the grid. The nominal power of the inverter is 900W.
https://www.ev-power.eu/GridFree-Inverters/GridFree-AC-Inverter-with-limiter-1kW-SUN-1000G-22-65V.html (USD 240)

In addition to the above key components, you need the fuse for the battery protection and the cables to make the installation wiring. You can get these components locally. (Estimated price of USD 50)

The total cost of the Micro Energy Storage Setup installation is about USD 1245 (ca. USD 400 less than in 2013).

In this setup, the Inverter is capable of running about 2 hours discharging the battery with 37A current. The connection of a few solar panels directly to the solar charge regulator allows getting energy from the sunshine during the sunny days. With 3 or more 280Wp panels it is possible to charge the battery during 2 to 3 hours of sunshine. 

In addition to the above components you may wish to get additional components to get the complete solution:

* Solar panel CanadianSolar Poly 280Wp 60 cells
In order to work efficiently with this 24V installation, the solar panels need to have the MPPT at 31V and more. We recommend using the 280Wp panels (MPPT at 31,3V). It is possible to have more panels in parallel to increase the speed of charging during the cloudy days.
CanadianSolar Poly photovoltaic panels of 280Wp offer high efficiency of 17,11% made from 60 high-quality cells (6x10 cells):
https://www.ev-power.eu/Solar-Panels/Solar-module-CanadianSolar-Poly-280Wp-60-cells-CS6K-280P.html (USD 100)

* 230VAC charger for 24V DC
You may wish to add a 230VAC charger for 24V to charge the battery pack. The battery pack may be charged from the grid at night (at the low/cheap energy tariff). In such installation, the battery pack is charged at night and the energy is released during the peak time of the day.
https://www.ev-power.eu/Chargers-6V-to-36V/Charger-24V-20A-for-LFP-LTO-cells-8-cells-BMS-input.html (USD 130)

The design of the energy storage is fully modular and allows to increase the size of installation easily by adding more batteries, more solar panels or more inverters.

This is to show that the DC power components from GWL Power allow making a simple solution for energy storage.

If you need any additional help, don't hesitate to contact us with further questions related to this setup.

All the listed prices are valid at the time of publishing of this article (updated 3/2019).