Solar PV Systems I , Spring 2011

Final ProjectBob McGonigle

Grid Tied Solar PV System

• Limited amount of space• High efficiency panels• Inverter limited to min startup voltage

Annual Electricity Usage 11.6 kWh

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Solar Pathfinder Results

Big Maple TreeBig problem !!!

Facing East

Facing West

PV Watts Analysis

Buy American (ARRA) Compliant Solar Panels

Zep System IIMounting System

Calculations

MODULE INFORMATION STCVOC = 36.90 VISC = 8.91 APtolerance = +5/-3%Max fuse rating = 15 APMAX = 245 WVPMAX = 29.8 VIPMAX = 8.23 AARRAY INFORMATIONNumber of modules in series = 5Total Watts = 1225 W

OPERATING VOLTAGEVPMAX = 29.8 VNumber of modules in series = 529.8 V VPMAX x 5 = 149 Volts

OPERATING CURRENTIPMAX = 8.23 AMAXIMUM SYSTEM VOLTAGEModule Voc = 36.9 VNumber of Modules in series = 5 Lowest temp. on record = -21.7°C

(Coefficient of 1.25 from NEC 690.7)Maximum System Voltage36.9 V x 5 x 1.25 = 230.63 Volts < 600 Volts

MAX PV SOURCE CIRCUIT CURRENTISC = 8.91 A8.91 A x 1.25 = 11.4 A8.91 A x 1.56 = 13.9 A

Calculations

WIRING OVERCURRENT PROTECTION

CONDUCTOR AMPACITYFrom PV Array8.91 AISC x 1.25 = 11.14 A11.14 A x 1.25 = 13.92 A

Record High Temp. 39.4°CAmbient Temp. Adjustment for conduit exposed to sunlight on rooftops 22°CAmpacity Correction Factor = .58 CFtemp

# of wires in conduit correction factor = .80 CFconduit

13.92 A ÷ (.58 x .80) = 30 A = 12 AWG USE-2

VOLTAGE DROPVdrop = Iop x Rc x LVdrop% = Vdrop ÷ Vop

Vdrop = 8.23 A x 1.93 x .019 = 301.79 mVVdrop% = 301.79 mV ÷ 149 V = .002025 < 1%

Calculations

INVERTER KACO Blue Planet 360Ixi grid tied invertermax. continuous power at 40°CDC input voltageAC output voltage range

MINIMUM INVERTER OUTPUT CIRCUIT CONDUCTOR AMPACITYInverter continuous output rating = 3600 WMinimum Inverter Voltage = 125 VMax Operating Current = 3600 W ÷ 125 V = 28.8 AMin. Inverter Output Circuit ampacity = 28.8 A x 1.25 = 36 A

Calculations

POINT OF CONNECTIONsum of the supply breakers feeding the busbar of a panel can be up to 120% of busbar rating100 A busbar100 A main breaker100 A x 120% = 120 APV breaker = 20 A

GROUNDINGWEEB Grounding Washers (between module and rack)WEEB Grounding Lug (to rack)

ARRAYMOUNTING INFORMATIONZep System II

Questions