First off, let me start by saying that North Carolina state government has renewed the 35% renewable energy tax credit for active solar, PV, passive solar, and other renewable energy systems. Coupled with the 30% federal tax credit (which now thanks to the stimulus has no cap for individuals), this is now a 65% off discount on these technologies if you pay enough taxes to use the credits. Remember, tax credits are directly subtracted from the tax amount you owe the feds and state, and you can roll the deduction forward for up to five years if you fail to use it all in the first year.
The major new change is that geothermal has been added to the list of renewables for the first time. There is a cap, but it is pretty high ($8400 on the credit) so many small/medium systems will not reach the cap. At 65% off, the price of a geothermal system can look a lot like the price for a high-efficiency air-source heat pump. And a geothermal system with a water to water heat exchanger to replace a boiler system powered by oil or propane can look like a fast payback. I will not just throw out numbers because different home sites will vary a lot, but if you pay taxes, geothermal should be very seriously considered for both new homes and upgrades of existing homes. Visit us at http://www.advdevco.com/ to learn more about us and custom home building.