Thanks to all for the replies so far - and the pointers to the EU regulations. They have thrown up another possible aspect which may be relevant.
Article 9 concerned with "Monitoring of aerodrome surroundings" says that Member States shall ensure that consultations are conducted with regard to human activities and land use such as: ...... 9 (d) the use of highly reflective surfaces which may cause dazzling;
The area where the building is being planned is within the Manchester Control area. In order to allow light aircraft to transit the zone in a North/South direction under VFR there is a light aircraft corridor ~4 nm wide with a height of 1300 ft.allowing. The solar array is right in the middle of the corridor and would almost certainly cause glare when flying North - admittedly when it's not raining!
The regulation doesn't define 'airport surroundings' but it seems to me the low level corridor can reasonably be interpreted to mean it's closely associated with the aerodrome since it's there precisely to facilitate transiting the aerodrome control area. I'd appreciate any further comments before I take the matter up with the CAA
It seems to me that the CAA - the relevant authority in the UK should be consulted on this but any further comments welcome before I approach the CAA.