… [W]e estimated the cost of electricity from residential solar PV in recent years and compared the figures with electricity rate (See the diagram). We presented a similar comparison in the earlier article on 4th December 2014, but this time we have revised the interest rate (discount rate) to match the reality. According to the current estimate, the cost of electricity from residential solar PV was 40 yen/kWh or so in around 2010, which was indeed twice as high when compared to the electricity rate, but the cost has continued to fall since. By the period from July to September 2014, the cost reached 26.0 yen/kWh, which was lower than the average electricity rate of the same year, which was 26.3 yen/kWh. The unit cost of power generation continued to fall and reached 24.9 yen/kWh by the period from October to December 2014. From these figures, we can assume with high probability that the cost of residential solar PV has become cheaper than the electricity rate in the latter half of 2014.
The above is based on the assumption that the electricity rate will remain constant for the next 20 years, however, there are many uncertainties about the cost of energy, as the risk assessment of nuclear accidents has become stringent, and there is also a fluctuation risk concerning costs of fossil fuels. Installation of a solar PV system is not only economically attractive to those installing it, but also helps them to reduce such uncertainties.
The cost of electricity from solar PV is already lower than electricity rates in some parts of the world. According to Grid Parity Monitoring (2015), Germany, Italy, Spain, Australia, Israel and Mexico already reached such levels between 2011 and 2012. Japan has caught up with the rest of the world at last.
— From “Grid Parity – Solar PV Has Caught Up with Japan’s Grid Electricity “
6 August 2015 by Keiji Kimura, Senior Researcher, Japan Renewable Energy Foundation
From Japan Renewable Energy Foundation. Entire article at http://www.jref.or.jp/en/column/column_20150730_02.php.