Where did you see that connect to the grid is required?  The expense should qualify so long as the original installation is completed pursuant to §25D:

(8) When expenditure made; amount of expenditure
(A) In general
Except as provided in subparagraph (B), an expenditure with respect to an item shall be treated as made when the original installation of the item is completed.

(B) Expenditures part of building construction
In the case of an expenditure in connection with the construction or reconstruction of a structure, such expenditure shall be treated as made when the original use of the constructed or reconstructed structure by the taxpayer begins.