We have had our Grid-Tie solar system installed for a little over two years.
In 2020 (January 13th,2020 through January 12 2021) we used 15,866 kWh of power, while our solar system generated 14,877 kWh or 93.7% of our total usage. We purchased 989 kWh from Duke Energy for $269.47 over the year of which $136.80 was the mandatory connection charge.
[In 2019 and 2018 we used 16,695 kWh and 16,695 kWh, so our overall usage was slightly lower than in past years, mostly due to the fact that we did a lot less commuting in the electric vehicles in 2020….something was different after March…..]
We saved $1,958 in 2020 (compared to $1,886 in 2019). Given the average yearly savings of $1,922 on our electric bill, the system will pay for itself after 9 total years of operation. (After that, any savings are pure profit.) As this calculation includes two years worth of data, I feel that it is slightly more accurate than the 9.19 year payback period I calculated last year.