Md. Code, Tax - Property § 9–203

(a) The Mayor and City Council of Baltimore City or the governing body of a county or of a municipal corporation may grant, by law, a tax credit against the county or municipal corporation property tax imposed on a structure, if to heat or cool the structure, to generate electricity to be used in the structure, or to provide hot water for use in the structure, the structure uses:

(1) a solar energy device;

(2) a geothermal energy device; or

(3) a qualifying energy conservation device.

(b) A county or municipal corporation may provide, by law, for:

(1) the amount of a property tax credit under this section;

(2) the duration of a property tax credit under this section not exceeding 3 years;

(3) the definition of:

(i) a solar energy device;

(ii) a geothermal energy device; and

(iii) a qualifying energy conservation device; and

(4) any other provision necessary to carry out this section.