7. The amount of tax to be repaid in accordance with Article 3 or reclaimed in accordance with Article 5 shall, subject to Article 8, be the tax incurred which the qualifying person shows to the satisfaction of the Revenue Commissioners to be referable solely to outlay which relates to—

(a) the construction, extension, alteration or reconstruction of that part of the building or structure which was designed solely for the purposes of a farming business and has actually been put to use in such a busi ness carried on by him or her,

(b) the fencing, drainage or reclamation of any land which has actually been put to use in such a business carried on by him or her, or

(c) the construction, erection or installation of qualifying equipment for the purpose of micro-generation of electricity for use solely or mainly in his or her farming business.