Solar Electricity in Japan
Our amazing month of exploring renewable energy (and many other fascinating experiences) in Japan has come to an end. This entry recaps what we learned about their use of solar electricity and some of the challenges our two countries share in pursuing more of our energy from this resource.
Our first exposure to solar photovoltaics (PV) in Japan was in Ninohe. We visited a government office and a hospital, both of which have solar PV systems. 
What we gleaned from these visits was that these were really showcase projects for the government. They weren’t installed because they wanted a return on investment but rather they simply wanted their government facilities to be at least partly solar-powered to demonstrate a commitment to clean energy. It was challenging to figure out the exact installed cost of the systems and how long it might take for the investments to pay themselves back. It was nice to see that the government clearly wanted to promote solar by using it, but our understanding did not get much below the surface.
In Kuzumaki we visited a school that had a 50 kW solar PV system. I was excited to see that because my company (Namaste Solar) is in the process of installing solar PV systems on 16 Denver Public Schools (DPS), and I was curious to learn more about what the students were learning in the school about their solar system and a
bout renewable energy in general. Unfortunately, it was the weekend, so we could not speak with anyone at the school. However, we did learn that there is some aspect of the curriculum that is focused on learning about solar. I look forward to facilitating a connection between students in Kuzumaki and DPS students next school year. Kuzumaki is known as the town of dairy, wine, and clean energy. They produce more clean energy from solar and wind power than the town uses. However, we still found it difficult to get consistent answers about the use and cost of residential solar PV. Our curiosity continued…
Over the last two weeks of the trip, I spoke with a few homeowners and business owners who have installed solar PV systems. One of my homestay families had a solar system installed on their apartment building, 
our hotel in Miyako
was partly solar-powered, and the son of another one of my homestay families had a solar-powered home. We received various answers when we asked questions about cost, payback time period, incentives from the utility company or the government, and the general enthusiasm for solar in the community. It seemed that the general feeling was that solar PV was still too expensive and therefore hadn’t made a significant impact in Japan yet. While costs for solar PV in Colorado have decreased 
considerably and interest continues to rise, these arguments sounded very familiar. However, we could see a fair number of systems on roofs as we drove around in various towns, so it seemed there was a noticeable segment of the population that thought solar PV was a good idea. Our curiosity continued…
In our final week of the trip we found ourselves back in the largest city in the area, Sendai. We had a chance to visit with some people at the local electricity company, Tohoku Electric Power Company.
However, the individuals we met with were focused on building and maintaining the company’s facilities, and it was challenging for them to answer questions about the company’s plans on renewable energy. Our curiosity continued…
We decided to inquire with our gracious Japanese hosts if we might be able to fit in a visit with 
a company that installs solar PV systems as this seemed the best way to really get to the bottom of what we were hoping to learn. They immediately made a few phone calls and set up an opportunity for us for the next day (this is indicative of their incredible efforts on our behalf throughout the trip). We met with Hokusho Housing, a homebuilder that also installs solar PV systems. They were able to answer so many of the questions for which we had received uncertain answers. It was fantastic! Here’s is what we found out:
- The average system size they install is about 3 kW. In Colorado it is a little larger than 5 kW.
- The installed cost is about $6/watt. This is similar to current prices in Colorado.
- The Japanese government provides an up-front incentive to homeowners of about $0.70/watt. Xcel Energy in Colorado currently provides a rebate of about $2.55/watt.
- There are no permitting fees. In Colorado, permitting fees vary by jurisdiction, but they all charge something.
- It is not the practice of Hokusho Housing to float the rebate for their customers. It is almost universal in Colorado that companies will provide this service.
- Anytime a solar system in this area is producing more than the home is using, the excess electricity is bought by the utility company at a rate of about $0.48/kWh. The homeowner then has a choice about how they want to purchase any electricity their home may need. They can either pay about $0.24/kWh anytime they need electricity, day or night, or they can pay a variable rate of $0.09/kWh from 11:00 PM to 7:00 AM and $0.30/kWh between 7:00 AM and 11:00 PM. In Colorado, we have net metering laws by which a homeowner receives an even exchange for any electricity sent to the grid and any they need to buy back. Our rates are about $0.10/kWh.
- The payback time period is estimated at 10 years. In fact, the government structured the incentive program (the combination of the upfront incentive and the per kWh purchase price) to ensure that the payback time period would be 10 years. If an installation company is charging too much per watt for the system to be installed, then the homeowner will not receive the upfront incentive.
- They expect the incentive levels to decrease over time as the cost of solar PV decreases. This is the case in Colorado as well.
- The installation techniques are somewhat different in Japan than what we typically do in Colorado. Almost all residential roofs in Japan are a traditional style of tile. I could not quite glean exactly what their process is, but they seem to have an easier way of installing panels on tile roofs than we are using in Colorado. I look forward to finding out more about these options to see if we can use them at home. In addition, it does not appear that they use ballast-only racking systems for commercial systems. When I tried to ask about this, they said that they have very good skills in taking care of the roof penetrations, so putting many holes in a commercial roof was not a concern.
That afternoon we visited Tohoku University. We saw several laboratories, one of which was focused on increasing the efficiency of polycrystalline solar PV cells. There are two primary methods for manufacturing crystalline solar PV cells, polycrystalline and monocrystalline. Polycrystalline cells are more common and less expensive, monocrystalline are slightly less common and more expensive but also more efficient. This lab is focused on keeping the manufacturing costs of polycrystalline cells low while improving efficiency. The primary way they are doing this is to make the crystalline structure more uniform and reduce impurities and defects. They have created a process called the “dendritic casting method” which tries to mirror the growth patterns of a leaf. They grow the leaf-like dendrite crystal on the bottom of a crucible of molten silicon. Then the polycrystalline silicon structures grow up from the surface of the dendrite crystal.
Unfortunately, we were not allowed to take pictures of the result, but it created a fan-like shape that was considerably more uniform than the conventional method. They are able to achieve an efficiency of 18.2% with this method compared with closer to 14% with the conventional method. Their goal is to get their efficiency above 20%. They are also working on creating a cell that is over 40% efficient by using a combination of silicon and other materials to create a more full spectrum cell. I look forward to any method that will create lower cost but more efficient solar PV cells!
Overall my take away message from studying the use of solar electricity in Japan is that they are focused on being leaders in R&D and manufacturing of solar PV modules, but they are at a similar point in their overall adoption of the technology for their energy needs as we are in the United States. I hope that our two countries can work together to ensure that solar is an integral part of our global energy future.
Written by Lauren Coyne
