My electricity bill for the last 12 months is $540.70. That averages out to $45.07 a month. If I assume that my monthly bill used to average around $250 a month, that is an annual savings of $2,459.30 a year. My solar panels have been operational for 11 years. That means I have saved a total of $27,052.30 over the period. Add in the $17,600 incentive received from the state on installation 11 years ago and my solar panels have generated $44,652.30 over the past 11 years.