You do not state which national park or which make and model of wind turbine. The Lake District National Park approved my Proven 6KW without requiring a bat survey, although as part of the application, I had provided a copy of Proven's Planning Pack, which covers ornithological issues but does not mention bats. Does the park already have 'domestic wind turbines' and did these require bat surveys? You should be able to find out by searching through planning applications, which are usually availabel on line.
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Simonridout