Residential Grid-Tie Photovoltaic System

Goal: The goal of this project was to design a fixed-tilt residential

grid tie photovoltaic system that meets the TVA Green Power SwitchGeneration Partners program requirements and be as efficient and costeffective as possible to maximize financial return on the system

Major Components:• Inverter(s) • Photovoltaic (Solar) Panels• Racking for Panels

Objectives:• Create a system that can be paid off in 10 years • Develop system that meets all requirements of TVA Generation Partners• Gain knowledge of how PV systems work• Develop an understanding of how utility interconnectivity works• Design a modular system that uses the Enphase M215 micro inverter• Design a second residential PV system that uses one large grid-tie inverter

TVA Green Power Switch:• 12 cent premium per kilowatt produced• 10 year contract for added premium• 500 watt minimum/50kW maximum system size• Federal tax credit for 30% of total cost available• $1000 for startup costs from TVA

“Grid Tie” Solar System

Michael CainAdvisor: Dr. J Douglas Sterrett

• Racking for Panels• Cables and Wiring

Final Design:• 9.6kW Panel Rating System – 40 Panels• Enphase M215 for Micro Inverter Design• SMA Sunnyboy 8000US for Centralized Inverter Design• Iron Ridge Scalable Ground Array for Racking• Canadian Solar CSP6-240 Poly-Crystalline Solar Panel

• $1000 for startup costs from TVA• System must have lockable disconnect•Must be IEEE 1547, 1547.1, and UL 1741 certified•Must pass electrical inspection by licensed electrician

Cost Analysis• Cost Analysis was performed• Payback occurred with-in project goal guidelines• Outcome better than one or two axis tracking

Enphase M215 Micro InverterSMA Sunnyboy 8000US

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2

4

6

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10

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18

$1,000 $1,500 $2,000 $2,500 $3,000 $3,500 $4,000 $4,500 $5,000 $5,500 $6,000

Payback Period in Years

Initial Capital Cost per kWatt

Payback Years versus Initial Capital Cost per kWatt

5-hours per day

6-hours per day

7-hours per day

Enphase

Single Inverter

6% Interest Loan

$0

$5

$10

$15

$20

$25

$30

$35

$40

$45

$50

$1,000 $1,500 $2,000 $2,500 $3,000 $3,500 $4,000 $4,500 $5,000 $5,500 $6,000

Monthly Payment or Revenue

Initial Capital Cost per kWatt

Monthly Revenue and 10-year Loan Payment versusInitial Capital Cost per kWatt for Various Solar Capacity

Hours per Day

5-hr revenue

6-hr revenue

7-hr revenue

10-year loan cost

Single Inverter

Enphase

6% Interest Loan