To amend the Internal Revenue Code of 1986 to extend for 3 years the energy investment credit for solar energy and geothermal property and to allow such credit against the entire regular tax and the alternative minimum tax.

Amends the Internal Revenue Code to: (1) extend for three years, through 1992, the investment tax credit in connection with depreciable solar energy property and geothermal property; and (2) permit this credit against the taxpayer's entire regular tax liability and minimum tax liability.