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Course Title
100 Home
101 Introduction
102 FAQ Page
103 Course Catalog
104 Green World
105 Demand & Supply
106 Conservation Careers
107 Solar Careers
108 Wind Turbine Careers
109 Entrepreneurs
110 Employee or Employer?
200 Demand Management
201 Summary
202 Residential Energy Profile
203 Ten Conservation Rules
204 HVAC System
205 Kitchen Appliances
206 Water Heater
207 Lighting
208 Laundry Appliances
209 Calculating Savings
300 Renewable Technology
301 Solar Energy
302 Solar Collectors
303 Solar Water Heating
304 Stirling Engines
305 Basic AC-DC Electronics
306 Silicon Solar Panels
307 Thin Film Solar Panels
308 Wind Turbines
309 Inverters
310 Grid Tied and Off Grid
311 Solar Site Survey
312 Solar Site Diagram
313 Sun Path Chart
314 Site Survey Worksheet
315 Wind Turbine Site Survey
316 Wind Turbine Worksheet
400 Solar Thermal Design
401 Solar Heat Overview
402 System Configuration
403 Site Survey
404 SRCC Compliance
405 System Specification
406 Bill of Materials
407 System Installation
408 Solar Heat Incentives
409 Document Package
410 Future Products
500 Solar PV Design
501 Solar PV Overview
502 System Configuration
503 Site Survey
504 Grid Tied & Off Grid
505 System Specification
506 Bill of Materials
507 System Installation
508 Solar PV Incentives
509 Document Package
510 Future Products
600 Wind Turbine Design
601 Wind Turbine Overview
602 System Configuration
603 Site Survey
604 Grid Tied and Off Grid
605 System Specification
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Green Collar Careers - Solar Photo Voltaic (PV) Design

Solar PV systems have come a long way over the last 20 years resulting in lower prices and major improvements to the entire package.  Increases in costs per kWh, decreases in the solar PV systems, and an enriched incentives almost makes the decision to install a solar electric generation a no-brainer.

Photovoltaic (PV) Panels are an array of solar cells connected together and packaged in a sealed unit capable of outdoor exposure for over 25 years.  Typically they cost in the range of $3 to $5 per rated peak DC watt output.  Not all PV panels are the same in characteristics;  two units may have the same peak power rating, but one unit may produce more power then another during low solar horizon periods or obscured conditions.  Prices per peak DC watts output are about half today of what they were 10 years ago.  Nearly all solar electric panels that are available today for residential use are poly-silicon substrate as thin films are not yet available for residential sale.  Most PV panels are wired with an output of between 24 and 72 volts per panel.  Panels are typically wired in series to step up DC voltage delivered to the inverter.

Inverters have seen many improvements over the last decade in cost, reliability, efficiency, and cleanliness of power generated.  Ten years ago inverters had a somewhat limited life of 5-7 years, today they have a life well in excess of 15-20 years.  Inverters typically cost in the range of $0.60 per watt.

DC Watts are the standard unit of measure for sizing a solar PV system.  A good quality 4000 Watt Grid-Tied package system cost run about $16,000 or $4 a watt.  Installation labor for a roof mounted 4000 Watt system takes about 40 man hours to install and we'll be generous and say $2000.  Total system cost of $18,000 or $4.50 per DC Watt.

Mark the system up by 25% ($4500) for your profit and the customer price is $22,500.

The average 4000 Watt system installation in America produces about $750 of electricity per year.  Higher in some areas, lower in others, that's just an average.  Without any incentives that means the return on Investment (ROI) in years is = ($22,500/$750) = 30 years.  No one would want it.

However the Federal Government is willing to offer the customer a tax credit of 30% on the system.  Utility companies in most states are willing to offer you an incentive mostly to buy the Carbon Credits the system provides.  Every utility is different, but some are paying over $2 per watt.  The table below shows the value:


4000 Watts DC Customer Price $22,500
Federal Tax Credit 30% -$6,750
After Tax Cost $15,750
Utility Incentive @ $2/DC Watt -$8,000
20% tax on Utility Incentive $1,600
Net System Cost $9,350
Annual Electricity Production $750
ROI (Years)  12.5
Added resale value to home $11,250

So what if the customer decides to sell their house in five years?  First they've taken the 30% tax credit on the system.  The next buyer can't do that.  Second, the resale value on the systems have been shown to be well over 50% of cost.  The next table shows how the owner comes out at 5 years:


Net System Cost -$9,350
Resale Value $11,250
5 Year Electricity Savings $3,750
Total return after 5 years $5,650

Similar to the solar water heating system, homes with solar electricity systems sell much faster then those without.  If you had a choice between two identical homes, one with a solar electricity system for half the system cost extra vrs one without, which would you choose?