You will need listed building consent to add solar panels to a listed building. You will need to contact your local planning authority who will help you. Historic England takes into consideration ‘minimum intervention and reversibility’  – so in order to obtain approval the solar panels must not damage the appearance of the building, cause major structural changes and once removed look like they were never there. Some historical buildings may not have roof materials suitable for solar panel installation like thatch, slate, or lead sheet.