Easiness to justify
Do not forget the deduction for investment!
You had solar panels installed? Deductibility wise, it is a pretty good idea, as you can judge here:
Are you self-employed as a natural person? You deduct in proportion to the professional use you have of them. You can calculate this pro rata by dividing up your electricity consumption between business or private purposes. Also take into account the depreciation of this investment, which is estimated to last 20 years.
Did you, as a self-employed in a company, install solar panels on the roof of your work space and your home? You can deduct the entire cost of their acquisition and installation from your corporate taxes. Your private consumption is considered as a benefit in kind, you are therefore taxed on it, as a remuneration, at the personal income tax level.
As far as VAT is concerned, whether you are a company or a natural person, you deduct (i) according to your professional use (ii) from the right to deduct VAT of the businesses that use these solar panels.