You mentioned solar water heaters in your list of available tax credits & incentives. I just wanted to point out that in addition to the solar models, the federal government is granting sizable tax credits (up to $1500) for tankless water heaters installed in 2009.

Here are some details of that particular tax credit:

“A Tax Credit of up to $1,500 is now available for 2009 as part of The American Recovery and Reinvestment Act of 2009. Homeowners can now receive a credit for 30% of the full purchase and installation price for installing Energy Efficient appliances such as tankless hot water heaters. To take advantage of this offer, you must install your energy efficient appliances between January 1, 2009 and December 31, 2010. Please save your receipts for tax record purposes.”