Just from its shape, large yellow underwing, Noctua pronuba.
Photographic note: if you'd set your camera to take account of the white background (overexpose by about 2 stops), you'd find the detail of the moth would not be lost in darkness. Better to get it right in the camera if possible. However, with digital photography, you have significant leeway, allowing you to regain much of the hidden detail by using an image editor to adjust the contrast/curves (terms differ). Also, cropping the photo to eliminate wasted space make the file much smaller (and hence friendlier to folks downloading it).
Here's your photo after a quick edit (I could regain only some of the shadow detail)
...which allows me to see enough detail to confirm my ID.