The development of  micro-girds  which combine several localized systems into a small power network has drawn  recent attention. They can operate either as a 

self-contained energy network or they can be integrated into a centralized power grid.  A variety of technologies have been studied to use solar energy systems as a form of  micro-grid  to enhance the reliability and performance  of the system. However, the operation of  these  systems  is not without problems, and  intermittency of the energy  from  the  sun  is  the major one. This thesis proposes a microcontroller-based solar energy management  system which combines  battery  management  and  storage technology to address this issue. This approach  uses an  energy system with  a solar panel array,  a maximum power point tracking  (MPPT) unit,  a battery management system, and a bidirectional inverter which is connected to the electric utility grid. Off-peak  energy  management  also  is  embedded  in  the system to further increase  the economic benefits.

An Abstract of    iii 

Acknowledgements  v 

Table of Contents  - vi 

List of Figures    ix 

11 Research Background and Motivation  - 1 

12 Literature Review    4 

13 Research Objective - 6 

21 The Battery Management System  - 7 

22 The Off-peak Energy Management System    11 

23 State of Charge (SOC) Calculation  13 

31 Solar Panel Array Supported by the MPPT Unit  - 16 

311 Solar Panel Array  - 16 

312 The MPPT Unit    17 

32 BMS and Battery Bank  20 

321 Battery Bank - 20 

322 BMS  - 22 

33 Central Control Unit - 25 

34 Graphical User Interface (GUI)    27 

35 Protection Unit  30 

351 Hardware  - 30 

352 Software  - 31 

36 CAN Function  - 31 

41 Performance of the BMS - 34 

42 SOC Estimation   35 

43 Graphical User Interface (GUI)    37 

44 Data Analysis  - 38 

A Introduction to Lead Acid Batteries  46 

B Thin-film Solar Cells    47 

C The Maximum Power Point Tracking (MPPT) Method   48

Figure 1-1 Diagram of Residential Grid Connected PV System  - 2 

Figure 1-2 Hourly Average Residential Load Profile  - 3 

Figure 2-1 Block Diagram of the BMS 9 

Figure 2-2 Flowchart of BMS Algorithm  10 

Figure 2-3 Off-peak Storage Strategy  12 

Figure 2-4 Example of SOC versus OCV Chart  - 14 

Figure 3-1 Solar Array with Energy Storage Battery  16 

Figure 3-2 The 1KW Roof Mounted Solar Array  17 

Figure 3-3 System Schematic 19 

Figure 3-4 Schematic of Boost Converter   19 

Figure 3-5 The MPPT Unit  - 20 

Figure 3-6 Lead Acid Battery  22 

Figure 3-7 Configuration of the ECU Module    23 

Figure 3-8 Configuration of the ECU Module    23 

Figure 3-9 Battery Bank with one BMS Local Module  - 24

Figure 3-10 The Complete Battery Bank Installation  25 

Figure 3-11 Central Module and PC with ABC150 Remote Control Panel  - 26 

Figure 3-12 ABC-150 Bi-direction Inverter  - 26 

Figure 3-13 Diagram of Inverter, Central Module, CAN Interface, MPPT Module, 

ECU Module, and EQU Module  - 27 

Figure 3-14 Page Showing the Initial Settings - 28 

Figure 3-15 Main Page   28 

Figure 3-16 Dispatch Function Page - 29 

Figure 4-1 Basic Schematic of the System  - 33 

Figure 4-2 Time Diagram of Vmax and Vmin with BMS    34 

Figure 4-3 Time Diagram of Vmax and Vmin without BMS  35 

Figure 4-4 Plot of Operation Current and SOC Curve Using OCV Method  36 

Figure 4-5 Plot of Battery Bank Operation Current and SOC Curve when Integrating 

OCV Method with Coulomb Counting Method - 36 

Figure 4-6 GUI and Data Plots for the Solar Battery System  37 

Figure 4-7 Time Chart of Solar Voltage and Battery Bank Voltage 38 

Figure 4-8 Time Diagram of Load Simulation and Output Current Provided from 

Solar and Battery Bank  - 39 

Figure A-1 Structure of a Lead Acid Battery 46 

Figure B-1 The Sketch of Solar Cell - 48 

Figure C-1 The Max Power Point of the I-V Curve and the P-V Curve 49