The best I can come up with (actual observational numbers) is an estimate of a solar radiation increase of 0.036 - 0.05% per decade (solar cycle max/min excluded). I'm not worrying about models or climate or clouds or cosmic rays or anything else. Now I request that you demonstrate this is sufficient to be the primary climate forcing factor on Earth and on other Solar System bodies. This seems like a pretty small change in solar output to me.
I'm just guessing but wouldn't you expect the temperature to rise linearly with solar radiation. If so a simple calculation using the .0005/decade figure gives a 2.67 degree Fahrenheit increase over a century. Isn't that about what we have experienced?