The document discusses various components used for data communication in renewable energy systems, including a communication gateway, data acquisition server, wireless transceiver, and monitoring software. The communication gateway bridges the gap between solar inverters and computers, sends reports via email, and has a price of $650. The data acquisition server provides connectivity for monitoring solar performance with a price of $1,649. The wireless transceiver provides wireless connectivity among monitoring devices, connects up to 128 devices to networks, and has a price of $535. Modbus is described as a commonly used serial communications protocol in industry.

1. Jan. 2008
Data communication in
renewable energy systems
George Wang

2. Jan. 2008
Grid Tie PV System

3. Jan. 2008

4. Jan. 2008
Small-scale wind turbine system

5. Jan. 2008
US Wind Power Capacity (MW)
1 vs. 5 year

6. Jan. 2008
Inverters

7. Jan. 2008
Communication ports on inverter

8. Jan. 2008
Setting up a connection

9. Jan. 2008
Data communication platform

10. Jan. 2008
Communication Gateway
• Bridges the gap between a solar
inverter and a computer.
• Includes built-in Wi-Fi and
Ethernet.
• Can be configured to send
energy and alarm reports via
email
• Embedded web page for
configuring and upgrading
inverter firmware
• The Gateway is sold at $650 list
price.

11. Jan. 2008
Communication Gateway Specs
Communication Physical layer 2, CAN
Communication protocol Xanbus™
Connectors 3 RJ-45 – 8 pins (2 Xanbus, 1 Ethernet)
Ethernet IEEE Std 802.3™-2005
Wireless 802.11.4b and 802.11.4g; WEP and WPA
security
North America EMC FCC part 15B class B
Industry Canada ICES-003 class B
Safety Low Voltage Directive 2006/95/EC
EN60950-1:2001
EMC EMC Directive 2004/108/EC
EN55022 A2: 2003
EN55024 A2: 2003
Telecom R&TTE Directive 1999/5/EC
ETSI EN 301 489-1 ver. 1.6.1
ETSI EN 301 489-17 ver. 1.2.1

12. Jan. 2008
Data Acquisition Server
• independent product
from the inverter
manufacturers
• provides “plug &
play” connectivity
for monitoring solar
system performance.
• It is sold at $1,649
list price.

13. Jan. 2008
Data Acquisition Server

14. Jan. 2008
Data Acquisition Server Specs
• Processor Main processor: ARM 9 ; I/O co-processor: ARM 7
• Operating System Linux 2.6
• Flash ROM 16 MB NOR Flash (expandable with USB memory device)
• Memory 32 MB RAM
• LED 8x pulse input, 4 modem activity, Modbus TX/RX, power status
• Console 2 x 16 LCD character, two buttons
• LAN 10/100, Auto crossover detection
• Modem (phone) V.34 bis, 33,600 bps (Part number A8812-1)
• Modem (cellular) GSM/GPRS Class10, 85 kbps (Part number A8812-GSM)
• Protocols Modbus/RTU, Modbus/TCP, TCP/IP, PPP, HTTP/HTML, FTP,SNMP, SMTP
• Power Supply 24 VDC, included
• Serial Port RS-485 Modbus
• Approvals CE; FCC Part 15, Class A
• USB port USB memory expansion port
• Power Requirement 110-120VAC
• Interval recording User selectable 1-60 minutes. Default 15 minute interval.
• Outputs 2x, Dry contact 30 VDC, 150 mA max
• Inputs 8x, user selectable:
– 0-10 V - Min/Max/Ave/Instantaneous
– 4-20 mA - Min/Max/Ave/Instantaneous
– Pulse - Consumption, Rate
– Resistance - Min/Max/Ave/Instantaneous
– Runtime - Runtime, Status

15. Jan. 2008
Wireless Transceiver
• Provide the wireless connectivity
among the monitoring devices.
• Submeter commercial and industrial
facilities
• Add Modbus devices to any network
without the need for costly
communications wiring
• Connect up to 128 RS 485 Modbus
devices to any Modbus network
• Use “Plug and play” connectivity for
supported devices to the data
acquisition server
• Unique “mesh” technology means
optimized routing of communications
• Accepts standard pulse inputs or
Modbus
• It is sold at $535 list price.

16. Jan. 2008
Wireless Transceiver

17. Jan. 2008
Modbus Protocol
• Modbus is a serial communications protocol published by Modicon in 1979 for use with its
programmable logic controllers (PLCs). It has become a de facto standard communications
protocol in industry, and is now the most commonly available means of connecting
industrial electronic devices. The main reasons for the extensive use of Modbus over other
communications protocols are:
– It is openly published and royalty-free
– Relatively easy industrial network to deploy
– It moves raw bits or words without placing many restrictions on vendors
– Modbus allows for communication between many devices connected to the same
network, for example a system that measures temperature and humidity and
communicates the results to a computer. Modbus is often used to connect a
supervisory computer with a remote terminal unit (RTU) in supervisory control and
data acquisition (SCADA) systems.
• Most Modbus devices communicate over a serial EIA-485 physical layer
• Limitations
– The number of data types is limited to those understood by PLCs. Large binary objects
are not supported.
– No standard way exists for a node to find the description of a data object, for example,
to determine if a register value represents a temperature between 30 and 175 degrees.
– Since Modbus is a master/slave protocol, there is no way for a field device to "report
by exception" (except over Ethernet TCP/IP, called open-mbus)- the master node must
routinely poll each field device, and look for changes in the data. This consumes
bandwidth and network time in applications where bandwidth may be expensive, such
as over a low-bit-rate radio link.
– Modbus is restricted to addressing 247 devices on one data link, which limits the
number of field devices that may be connected to a master station (once again
Ethernet TCP/IP proving the exception).
– Modbus transmissions must be contiguous which limits the types of remote
communications devices to those that can buffer data to avoid gaps in the
transmission.

18. Jan. 2008
Monitoring Software