This document discusses a proposed power distribution system using solar energy for disaster recovery optical nodes. It proposes: 1. Using solar energy and reconfiguring solar panel connections to efficiently extract power during partial shading conditions, which reduces overall efficiency. 2. A tightly cross-tied solar panel structure that can be reconfigured into different connections to maximize power extraction under row and diagonal shading scenarios. 3. Simulation and experimental results showing the proposed reconfiguration technique can improve maximum output power from solar panels under shading conditions compared to a non-reconfigured system.

1. I/UCRC
Connection One Industry Meeting – April 10, 2015
Relay of panel1Relay of panel1
MOTIVATION
POWER DISTRIBUTION SYSTEM AT ASU
EFFICIENT POWER EXTRACTION & DISTRIBUTION SYSTEM
FOR DISASTER RECOVERY
Hrishikesh Deshmukh, Shishir Shukla, Sayfe Kiaei, Jennifer Kitchen
Arizona State University
• Solar Energy as an alternate source to power optical
nodes during disaster times.
• Data traffic through optical nodes is managed based
upon available solar power.
• Total generated and consumed solar power is
monitored and communicated to the optical network
[load] at any point of time.
Relay Switching Example
Optical Node Setup at University of Arizona
EFFICIENT POWER EXTRACTION FROM PV PANELS
• Partial or non-uniform shading affects PV
output power, thus reducing overall
efficiency. (Pmax reduced on P-V curve)
• Proposed Solution – Array Reconfiguration
• A TCT ( Tightly cross tied) structure is
chosen for reconfiguration, due to its
averaging ability and longer shelf life.
• Reconfiguration enables maximum power
extraction under partial shading.
Most Common Types of Shading
Proposed Architecture for Reconfiguration
-50
-40
-30
-20
-10
0
10
20
0 50 100
%POWERIMPROVEMENT
SHADING PERCENTAGE
DIAGONAL 1-2
DIAGONAL 1-3
DIAGONAL 1-4
DIAGONAL 1-5
0
5
10
15
20
25
0 20 40 60 80 100
%POWERIMPROVEMENT
SHADING PERCENTAGE
DIAGONAL 1-2
DIAGONAL 1-3
DIAGONAL 1-4
DIAGONAL 1-5
0
50
100
150
0 20 40 60 80 100
%POWERIMPROVEMENT
SHADING PERCENTAGE
ROW4 SHADED
ROW3,4 SHADED
ROW2,3,4 SHADED
PV11,PV12 SHADED
PV8,PV9,PV11,PV12 SHADED
Type-I(row) shading
with Type-I Reconfiguration
0
2
4
6
8
10
12
14
16
0 20 40 60 80 100
MAXIMUMOUTPUTPOWER
SHADING %
NON-RECONFIGURED
TYPE-I RECONFIGURATION
0
5
10
15
20
0 20 40 60 80 100
MAXIMUMOUTPUTPOWER
SHADING %
NON-RECONFIGURED
TYPE-I RECONFIGURATION
TYPE-II RECONFIGURATION
Type-II(diagonal) shading
with Type-I Reconfiguration
Type-II(diagonal) shading with Type-II
Reconfiguration for a 4X4 structure
SIMULATION RESULTS
IMPLEMENTATION ON A 2X2 STRUCTURE
Driver for eGaN Devices Board Design with eGaN driversNo. of switches = 4mn-n-3 = 11
Type-II(diagonal) shading with Type-I Reconfig. Type-II(diagonal) shading with Type-I Reconfig.
• Number of switches (N): N = 4mn-n-3
m:number of rows
n:number of columns
• Panel Rating: 36V, 5A ( 72 cells of 0.5V,1A in
series with bypass diodes per 24 cells)
• Switching device : eGaN (EPC2015)
High VDS breakdown , Low RDS(ON)
• True for symmetric as well as asymmetric
structures.
• Type-III Shading ( column shading ) in a TCT
structure does not give any improvement
for the proposed type of reconfiguration.
• Preferred Reconfiguration:Asymmetric
structure
Symmetric
structure
Type-I Shading
(row shading)
Type-I
reconfiguration
Type-I
reconfiguration
Type-II Shading
(diagonal
shading)
Type-I
reconfiguration
Type-II
reconfiguration
after specified % of
shading
Outdoor Experimental set-up
CONCLUSION : Maximum power is extracted using the proposed reconfiguration technique, and monitored in disaster zones.
Outdoor Experimental Set-upHardware Set-up for Power Monitoring
Relays are switched to give the closest required power.
Type-II reconfiguration (bypassing)
Type-I Reconfiguration(to column)
Panel rating : 5V, 1A