What is the size of the windfarm in wexford that has more than 19 turbines and a vendor of Enercon?
CREATE TABLE "completed_onshore_wind_farms" (
  "wind_farm" text,
  "capacity_mw" real,
  "turbines" real,
  "turbine_vendor" text,
  "size_mw" text,
  "county" text
);
SELECT "size_mw" FROM "completed_onshore_wind_farms" WHERE "turbines">19 AND "turbine_vendor"='enercon' AND "county"='wexford';