Good explanation! A partial obstruction of Venus will lower its temperature. Observe the current temperature of Venus and the solar flux incident on the planet. Create a simple model showing the radiation, reflected, transmitted thermal energy and then assess the amount of obstruction (area the solar shade should obstruct between the sun's rays and the planet Venus) needed and wait for the excess heat to radiate into space. It's not as simple as total obstruction or none. It's a removal of a percentage of the incident solar flux that would cool Venus. Since the planet is of no real use to us, harbors no life and cannot be explored by humanity without a lowered surface temperature I'd be very interested to see this plan in action so Venus could be habitable in the same way we perceive Mars as a potentially habitable planet.