I do not recommend the Solarize filter. For more realistic results, try the following.

1. Duplicate your image layer so that you have two copies of your image by choosing Layer > Duplicate Layer.

2. Make one of the layers a negative image by choosing Image > Adjustments > Invert.

3. Now change the blend mode of your top layer to Difference by choosing Difference in the mode pull down menu on the layers palette. (It does not seem to matter which of the two layers is on top.)

If you know a better way, I would love to hear about it. I never claimed to be an expert.

That's it, but I encourage you to experiment with different blend modes and opacities on the top layer

OR

Try this: Do steps 1-3 then merge the two layers and apply the Solarize filter to the resulting layer.