PV Gap

Elmer Said:

Do you still have to pay electricity bills if you have solar panels on your house?

We Answered:

If you are totally off the grid and generate 100% of your own power, then you'll get no billing from the power company. Instead, you'll be paying through the nose to the company that installed your solar power system until it is paid off.

Most solar power systems retain a connection to the grid. If you use more power than you generate, you'll get a bill from the power company. You will be billed at about 10c per KW used. If you generate more power than you use, the power company will buy that power from you (you'll get a credit) at about 3c per KW.

During the night, your solar system will not generate any power. All the power you use will come from the grid. During the day, you might use power from the grid, and you will also use power from your solar system. If, during the day, you generate more power than you use, your electric meter will run backwards, giving you a credit on your bill.

Let's say for example, during the month, you use 2000kw of power from the grid. Your solar system generates 500kw. You will be billed for using 1500kw. If you generate 3kw of power during that month, you will get a credit of $30 for that 1000kw of excess power (1000kw @ 3c/kw) that you put back onto the grid.

Eugene Said:

How much electricity would be generated if the entire surface of the earth was covered with solar panels?

We Answered:

A lot. Treating the earth as a disc, with a diameter of 13,000 km, we get an area of 531 trillion square kilometers, and at 100 watts per square meter, we would have 53 quadrillion watts -- about 50,000 times the installed generating capacity of the US. But much of that area is ocean, and much of the rest is too far north or south to be useful for power generation.