MPs have extra protection for the things they say in parliament. If he did say this in parliament it would be much harder to bring about chargers related to hate speech, encouraging violence etc.
It would also be immediately challenged and rebutted by well informed MPs. Resulting in a very humiliating clip for Farage. Hence, why he makes these comments on social media where he isn’t directly and immediately challenged.
To add to this most of the suns energy leaves the planet. Very little is retained. What the sun provides is a source of low entropy.