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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:

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:

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?