Each panel is a bit more than 4 feet wide by 3 feet high, measured center-to-center of the mounting screws:
about 4 foot, plus 1.25 inches wide by about 3 feet plus 1.75 inches high,
center-to-center of the screws (the glass panes are obviously smaller, because
some space is consumed by the mounting hardware and framing).
The slope is about 20 inches drop over 15 feet distance, i.e. at 15 feet (180
inches) back, it has dropped about 20 inches, so that's a slope of about
1 foot down for every 9 feet back:
Here are some additional pictures:
link,
and here are
some pictures from the inside:
an indoor "greenhouse for people":
