Luzcadiz, thank you for your comment.
For 7 years I owned a boatyard on the Tamar in Devon. ‘Docamenti’ is a familiar matter to me. VAT, Nat Ins, PAYE, ‘elf and Safety …. I had a bloke from the Min of Ag and Fish turn up one day to inspect my ‘Animals Prohibited To Come Ashore’ sign [“A bit rusty…..”]. Queen’s Harbour Master Devonport paid me £10 p.a for a speed limit sign on a post by my slipway. Though I could believe that a modest 2-bed short-let flat in Spain involves more bureaucracy than the boatyard.
Your suggestion of solar water heater is a good one. If the communidad would allow the installation, the pipe could run down the lightwell straight into either the bathroom or kitchen and then T off to the other. As I’m effectively 3 storeys below the roof, the pressure would be enough to blast barnacles off a hull.
But note my confession in my reply to Poppy. How do these tariffs work?