I like what you have done as far as the kitbashing, and since it was an open beta, I decided to download and try her out for Myself so here is my take on the Solaris.
Included are some screencaps that explain my thoughts better.
First, As bones has stated, there are a few problems with the textures and how they match up as seen here.
The fed symbols should match,also the bottom saucer section should have something there, looks empty to me. Maybe consider re-texturing the engines to match the look of the ship more.
Took her to the Itari system where at least thirty tholian ships gave me a warm welcome. one Tholian ship is no match for her of course, but a pack gave me quite a good battle, as you can see,
but I did survive.
The lower saucer phasers came through the top of the saucer at times, but not very noticeable. You should work on the power distribution levels on the warp core as well, has very little energy loss with all systems at 125%.
She also doesn't have the fed standard warp sound when engaging warp, though that may have been your intent. Just thought I would mention it in case it wasn't.
I enjoyed taking her for a spin.
