Sunday, November 17, 2013
Martin: Living off the grid
Wednesday, November 13, 2013
Kondadai - forest in the city
(This article is not about solar sharing, but the topic is at least as important.)
Kondadai is a piece of forest about 4 km from Tsukuba station in the city of Tsukuba, Ibaraki prefecture.
I naturally took the resident view because Kondadai reminded me of Brezina, a forest park in my hometown back in Slovakia.
This is Brezina in January 2013 - the last time I was there.
Monday, November 4, 2013
Nishigoya Opening ceremony 2013/10/27
Nishigoya Solar Power Plant of Ken Matsuoka began operation on October 15, 2013. The opening ceremony was held soon after - on Sunday October 27.
It was the sunniest Sunday you could wish for an event at a solar power plant.
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Matsuoka started his address with self-introduction: "I'm Ken Matsuoka, chief of Nishigoya Solar Power Plant."
He laughed and the audience too. "Power plant chief" was an exact description of his role in the project, and yet the words somehow sounded too big. Not many people can introduce themselves as power plant chiefs. Not many people know someone who'd be a power plant chief. I was proud to be one of them.
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Among the guests there were family members and friends who volunteered their time to help build the plant, and also some VIPs - like the father of solar sharing Akira Nagashima and Japan's ex-prime minister Naoto Kan.
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Here at the ceremony I heard for the first time the story of how it all began a year and a half ago:
By a series of coincidences, Ken Matsuoka happened to visit the Naoto Kan's office as a technical support for an interview. During the interview, Mr. Kan showed them materials on his desk: "Look at these amazing renewable energy projects."
On the desk, Matsuoka saw a photo of solar sharing. "I just found what I want to do," he allegedly murmured.
Next day he contacted Akira Nagashima.
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About the plant:
Matsuoka's plant consists of 579 panels (100W/panel) installed on a metal frame at the height 3.5 meters over an area of about 1500 m2. The plant's capacity - maximum output to sell to electric utility - is 49.9 kW.
A special feature of Matsuoka's plant is a winch allowing to change the tilt of all 579 panels (more than 8 tons) at once. The device, according to Matsuoka, didn't cost more than 1 % of the total investment, but it could increase the output by about 5 % - that is a significant number over 20 years.
We could see the effect of the winch at the ceremony.
First, Matsuoka and four selected guests turned on five inverters - this was a power plant version of ribbon-cutting ceremony:
Saturday, November 2, 2013
The Inventor
On October 23, 2013, I met Akira Nagashima at his Solar Sharing Trial Site (ソーラーシェアリング実証試験場) in Chiba prefecture.
Akira Nagashima, the inventor of solar sharing, is a celebrity in the community of solar sharing enthusiasts.
There are two plants on his trial site, both connected to public grid. Each has an output of about 4.5 kilowatts. There are many solar sharing projects in Japan, but this site is special because it's the first one. All others are imitations of this one.
Plant No. 1 (一号機) is installed above the garden. On the picture you can see peanuts, carrot, leek, taro and a row of unindentified leaves growing under the panels. Nagashima is standing on the side.
Plant No. 2 (2号機) is installed above a parking lot. Nagashima is standing below with a customized module that just arrived from manufacturer.
It still feels strange to call this kind of solar installation a power plant. For too long time we used to think of power plants as big unsightly buildings somewhere faraway.
Definition: Power plant is a complex of structures and equipment for generating electric energy from another source of energy.
Solar panels on the pictures above generate electricity from sun - they are legitimate power plants.
Monstrous appearance we expect from power plants is, luckily, optional. Solar sharing plants so far unticked this option - they're neither big nor ugly nor remote.
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Eureka moment
The idea of solar sharing first popped up in Nagashima's mind 10 years ago - in late 2003. Nagashima, now 70, was then studying law at Keio University in Tokyo (yes, at the age of 60). Nagashima got a biology textbook in his law course.
Why would one need a biology book in a law course?
Good question. I forgot to ask.
In that biology book, Nagashima came across the concept of light saturation point.
Light saturation point: Plants need sun to perform photosynthesis. We tend to believe that the more sunshine plants get the better, but this is not true for most plants. The reason is that most plants have a light saturation point - the amount of light intensity beyond which photosynthesis rate doesn't increase. All light beyond this saturation point is not only useless, but can even be stressful to the plant (for example causing overheating and water evaporation)
The concept of light saturation point led to Nagashima's eureka moment: If plants don't need all sunshine they're getting, why don't we use the excessive rays for power generation? Instead of laying solar moduls directly on the ground, we can put them a few meters higher and with spaces in between, so that plants below can still get their share of sun and keep growing.
The idea was out there and the time was ready for the next step: work out details and give it a real, tangible shape.
And a name.
Solar Sharing Trial Site was established in May 2010. Plant No. 1 started operation in August 2010 and plant No. 2 in April 2011. This was the only solar sharing project in Japan at that time.
Low-tech