the amount of your electric usage isnt really the determinative factor. you can buy as many panels as you want and any extra energy you produce goes back to the grid. the investment is relatively propertional to the amount of electricity you want to produce. in fact, you a rent generally using your own electricity, you sell it back to the grid whilst you’re away during the day, come and use what you rpoduced at night, though your night electricity is probably from coal or something.
you’re still connected to the grid and your meter.