For Sat TV, since most all the sat receivers have 120 volt cords, you will need an inverter,,, I strongly recommend a True Sine Wave type.. There are some in the 300-400 watt range that may be big enough to run your receiver and TV (if that is it is a modern flat screen,,, 300 watts may or may not run a CRT and likely will not run a plasma)
Put the inverter in a compartment near the batteries (Near but NOT the same compartment) use heavy cables between inverter and batteries (Starter cable for inverters up to around 750-1000 watts top) and then run standard electrical wire from there to an outlet near the electronics.