The best all-year-round angle for PV (photovoltaic) solar panels in the UK is 35-40 degrees. The best angle for each region within the UK will vary slightly within this. For seasonal. If you have a solar system that can move with the seasons, whether manually or automatically, you will need to calculate the tilt according to the time of year. For example, you will want your panels to be more vertical in the winter,. For summer you can do this by subtracting 15. For example, 34 -15 = 19. You would want a 19-degree tilt. For winter work out your solar panel tilt by adding 15 to your latitude. So, if your latitude is 34. 34 + 15 = 49. Your solar panels need a 49-degree. Having a completely flat solar panel array will still get a good amount of sunlight to generate energy. However, it is worth considering the fact that the flatter they are the less efficient they are.