Local electricity generation is one of the key challenges of technology for developing regions. Although we were driven by the need to power rural connectivity solutions, the approach described here makes sense for any remote ICT project with power needs up to about 100 W, which includes most home solar systems, as well as single PC projects, such as kiosks.
The primary concern is to provide reliable electricity for our WiFi-based long-distance (WiLD) links, particularly relay points. The relay point may be in the middle of a remote area where no grid power is available. Furthermore, even in areas served by the grid, power is often unreliable.
Note: Detailed report on the TIER Solar Controller is here (in PDF).
The charge controller implements maximum power point tracking using a PIC microntroller. Power point tracking is seen to have increased solar panel output up to 15% compared to a simple direct connection between the solar panel and the battery. Switch-mode power conversion used with the power tracking has a typical efficiency of 95%.
Voltages and currents of the solar panel, battery and load are reported through the Ethernet connection of the device. Status reports may also be monitored through the serial port.
The devices provides power over Ethernet through the RJ45 port (assuming battery is sufficiently charged). Typical output voltage is 12 volts. PoE is disconnected when battery voltage drops below the minimum safe voltage.
To address the need to power different types of routers, the previous board has been revised. The revised board (shown below) can be configured to output, through the PoE 12V-48V. Power capacity through the PoE is limited to 24W. 12V output is still available through the load terminal.
You can find a set of files related to this version here, including:
See this page for details on the planned 4th revision of the solar charge controller.
Please contact email@example.com for questions. We'd be glad to collaborate on improving the Microgrid Management System to meet your requirements.