Photos shown on uncalibrated monitors are not going to be graded correctly. If you’re not doing any color adjustments, you may just be lucky that your PC monitor is faithful to what you expect to see, or maybe it’s showing you total fiction. Can’t really tell without color calibration. About all you know is that your monitor and your TV are different. And unless you have a CRT or LCD IPS or PVA/MVA monitor, there’s no special reason to expect your monitor to be the correct one here.
The best calibration is with a calibration tool. I use a fairly cheap one called a Huey Pro, from Pantone, which is probably out of production. Anything’s better than nothing. But without this, you can get a decent calibration if you have a color-aware application (like Photoshop) and a color profiled printer, like pretty much any Epson. Print a test pattern, a photo, etc. and compare to the colors on your monitor. Adjust accordingly.
Now take those same photos and test patterns to your TV. Adjust accordingly.
Also, check your DVD collection for any DVD with the “THX” logo on it (or see here: https://www.thx.com/home/dvd/search.html). THX DVDs include a short color calibration segment (“The THX Optimizer”) that will offer a very specific series of images to help you set dark levels (adjust brightness), light levels (adjust contrast), and color properly. You can run this on your PC, too.
-Dave