Federal incentives apply to both solar hot water systems and solar electric (PV) systems.  
The utility incentives only apply to PV installations.

Federal Residential Renewable Energy Tax Credit

    30% Personal Tax Credit, no maximum, excess credit may be carried forward.

Federal Commercial, Industrial, and Utility Energy Tax Credit

    The credit is equal to 30% of expenditures, with no maximum credit. Eligible solar
    energy property includes equipment that uses solar energy to generate electricity, to
    heat or cool (or provide hot water for use in) a structure, or to provide solar process
    heat. Hybrid solar lighting systems, which use solar energy to illuminate the inside of a
    structure using fiber-optic distributed sunlight, are eligible. Passive solar systems and
    solar pool-heating systems are not eligible.

U.S. Department of Treasury - Renewable Energy Grants

    Federal Grant Program for Commercial, Industrial, and Agricultural Solar Water
    Heating, Solar Space Heating, Solar Electric, and other renewable technologies.

Tennessee Valley Authority:

    They do have a program that is inviting.  Here is a list of power companies partnering
    with TVA to offer Green Power Switch.  Qualifying systems receive a $1,000 incentive
    to help offset start-up costs.  Then, they purchase your excess power at 12 cents per
    KWh premium guaranteed for 10 years.  There are some requirements that you must
    meet, but Solar Tech Alabama will take care of that for you.  This is a good deal!

Alabama Power Incentives:

    Alabama Power Company does not offer any real incentives at this time.
Solar Technology Alabama
Incentives
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