1 If the patent application was filed on or after June 8, 1995, the starting patent term is 20 years. 2  This accounts for the vast majority of patents in force today. 3  The 20 year term is calculated based upon the priority filing date, not counting provisional application or the original filing in a foreign country.
The report indicates that the median installed price of PV systems completed in 2012 was $5.30/W for residential and small commercial systems smaller than 10 kilowatts (kW) in size and was $4.60/W for commercial systems of 100 kW or more in size.
In addition, costs for fossil fuels may creep up due to raw material costs, shipping costs, and possibly carbon dioxide taxes. At an installed price of $1.25 per watt, the cost of PV solar is always cheaper than coal.At $2 per watt, it is cheaper after year 40.At $3.00 per watt, it is cheaper about year 80. roof top solar system has no moving parts, so it has a long expected lifetime exceeding 25 years (used in this example). However inverters (which convert the panel DC current into AC) have an expected lifetime of 10 to 15 years. In our example we add the cost of a replacement inverter to the system after 12 years.