Yes, you can. Even if you get paid for your solar-generated energy – either under the smart export guarantee (SEG) or the previous feed-in-tariff (FIT) scheme, which closed in March 2019.
Both schemes pay you for the energy you generate, but your SEG or FIT provider doesn't have to be the same as your energy supplier, so you're free to switch. For more info on both schemes, and switching energy with solar panels, see our Solar panels guide.