Electricity is traded in half-hour settlement periods; in each period the power that meets the peak demand is called the Marginal Generation Unit (MGU) and it is that price that sets the wholesale price. The MGU is nearly always gas, so the wholesale price tracks the gas price pretty closely. Read more

If you have solar panels you don't care too much about their efficiency, you care about how much energy you get out of them. You'll get the most energy on long summer days. Read more

No, but they are less efficient. Read more