It is very difficult to predict the future solar energy development in Japan. After the Fukushima accident the Japanese seemed to abandon nuclear energy and turn to solar and other renewables as replacement options. Since 2012, Japanese government also introduced feed-in-tariffs which forced electricity providers to buy power from renewable energy suppliers.
This opened the door for many large solar energy projects such as massive floating solar farm near Tokyo which should power approximately 5000 average Japanese homes in 2018.
However, the government support for solar energy seems to be waning in Japan and Tokyo's long-term's commitment to renewables looks seriously in doubt because government is looking to kickstart nuclear energy back in the mix even despite the public perception.
The utilities support government because they feel they lost plenty of money buying renewables in times when oil and fossil fuel prices remain very low.
Not only does Japanese government plan to open the door for nuclear power once again, it is also said to be very supportive of building new coal power plants. Though coal is cheap it is also the dirtiest fossil fuel, and while many other countries are running away from coal Japan currently looks to be embracing it.
These are the reasons why the future of solar energy in Japan is still far from being certain. On one hand, government calls for more green power while on the other it wide opens the door for more nuclear and fossil fuels.
Solar power currently accounts for just around 3.3 percent of Japan's energy mix. The government has already announced plans for solar and other renewables to provide for 22-24 percent of country's total energy mix by 2030.