Do you need to pay for electricity if you have solar panels?

I am in the market for buying a home. There is one for salke that actually has solar panels on top. How are they used? Do you need to pay for gas and electric still. Does it really light up the house and keep it warm. WHat about the AC keeping hte house cool in the summer does it work for that too? Please explain in solar for dummy terms. I haveno clue about solar panels other thatn the fact that it needs sunlight to run.

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