Power plant performance in numbers (Dec. 2014 - June 2015)

Here is a summary of the monthly performance of our power plant from December 2014 (the first full month of operation) until June 2015.

The best performing month so far was May with 6231 kWh of electricity produced, and the worst month was February with 4460 kWh. An average Japanese household consumes about 300 kWh of electricity a month, so our power plant produced enough electricity for 14 households in its weakest month (February) and for 20 households in the strongest month (May).

But some months have more days than others. When we take that into account and calculate average amount of electricity generated per day in a given month, we'll find out that the worst month in fact was not February (28 days) but April (30 days) - an average of 148.8 kWh was generated a day. The best month remains May with average daily performance of 201 kWh. See the graph below:

The size of our power plant is 40.71 kW in terms of installed capacity of solar panels (354 panels x  0.115 kW), and 38.5 kW in terms of maximum capacity of inverters (7 inverters x 5.5 kW). 

The question I am interested in is: How many kilowatt hours of electricity does each 1 kW of installed capacity generate per year?

As our power plant has been in operation for only seven months, I don't have  a twelve months worth of statistics yet. But if I assume that the same trend will continue for the next four months, I can extrapolate data from the seven months introduced above. 

Power plant Oo generated a total of 35 022 kWh of electricity in the seven months from Dec. 1, 2014 until June 30, 2015. This gives us average performance of  5003 kWh/month.

This multiplied by 12 months gives us a prediction for yearly performance. 

5003 x 12 =  60037 kWh/year

When we divide this yearly performance (prediction) by the installed capacity 40.71 kW, we'll find out that 1474 kWh of power will be produced annually per 1 kW of installed capacity. 

60037 kWh / 40.71 kW = 1474.76 kWh 

This is very good result. 

Actual performance depends on many factors so it's hard to make simple comparisons, but just for reference, Japanese makers of solar power systems such as Sharp, Panasonic and Toshiba estimate annual energy production per 1 kW of their products somewhere between 1000 and 1200 kWh. (Source: Eco-hatsu {in Japanese}). In the light of that, our power plant's estimate of  1474 kWh per 1 kW of installed capacity per year is an excellent outcome. 

So why is it important to push performance to the maximum?
Of course on the individual level there is financial incentive - for me, each kilowatt hour produced means a few more yens earned. But it's important from the global perspective as well: Solar power systems take a lot of energy to manufacture and install, and they have to "pay" this energy back. The more energy our power plant produces, the shorter is its energy payback time, and the higher is its net energy gain.

Energy payback time is the time it takes a solar power  system to generate the same amount 

of energy that was used for its manufacture and installation. So how long is that time? On average, it's "between six months to two years, depending on the location/solar irradiation and the technology," according to this 2012 article from the Center for Life Cycle Analysis at Columbia University. That's already quite short. But it can always be shorter. 

The world's cutest weed cutter

Let me introduce you to the cutest weed cutter in the world:

Natchan (front) and her friend Kaakun (back) 

Her name is Natchan. Natchan and her friend Kaakun come to our power plant almost every day to help out with an otherwise daunting task of weeding (that is, weeding a thousand square meters of land). I would love to use a friendlier expression like "lawn mowing" instead of "weeding," but what really grows at our power plant are weeds, not a lawn, and the activity we engage in is the War on Weeds. War is sometimes brutal, but however strong the enemy might be, the one thing we want to avoid is chemical weapons (=herbicides). So we fight with traditional armaments: a sickle and a scythe (for me) and a weed cutter (for Nobuo). But with two goats joining our ranks, it's an easy victory.

Talking so much about weeds might seem like too much fuss about nothing, but if you ever experienced Japanese summer in the countryside, you know that if you don't interfere, weeds soon grow over your head (literally). So much as I admire the vitality and ingenious survival skills of Japanese weeds, I have to fight them back. And I am grateful for our goat-friends' help.

Here's Natchan at work:

Natchan is not only the cutest but also the most enthusiastic weeder I've ever met. She never complains of working too hard or having eaten too much of  the weed. For comparison - Nobuo starts whining after 5 minutes of weed cutting and takes a break after 10 minutes (sometimes never to resume again.) Who would you take as a team member on a weeding mission?

Here's Nobuo exchanging weeding tips with Natchan:

Nobuo (right) chatting with Natchan (left).

Natchan and Kaakun are our neighbor's goats. Our power plant  is located in a rural part of Tsukuba, with many fields around. There's a lot of grass and weeds everywhere, most noticeably on the sides of the rice fields,  so it seems that our neighbor wouldn't have to bother to come to our place to graze her goats. The main reason why she comes here and not elsewhere is the chemical weapons - we don't use them, but most farmers around do. That makes our power plant a safe place for goats (and frogs and sparrows....) to graze.

It's a truly win-win situation.  Goats are happy to have fresh grass for lunch and we're happy to be exempt from the weed cutting task. I hope this collaboration will continue for very long time.

Chickens' first time on new playground

Our chickens can finally play on the grass outside the coop (click on picture for enlargement):

2015/6/22 morning. Chickens on their new playground.
(Visual distortion on this and other pictures is due to the fisheye lens of our Sony action camera)

Here are their first moments out of the coop:

On their new playground chickens are busy pecking everything that comes in their way, eating grass and chasing bugs. And digging ground for more bugs and seeds and other yummy stuff. Before, they used to flock around me when I came to feed them. Now they hardly notice when I come.  Which I take as a sign that they're happy on their own.

This is view from outside:

2015/6/22 morning. View from the south-west. 

2015/6/22 morning. View from the south-east.

The fence is made of metal lattice panels that we got for free from a new local friend of ours who happened to have an old fence he didn't need any more. We're happy that we could reuse something instead of buying new stuff. Reusing old fence also made it much cheaper for us.  

To put up the fence we needed fence posts, for which we used supporting poles of the power plant. This is one of the instances when having a solar sharing power plant on your land is more convenient than not having one. The fact that we didn't have to erect new fence posts saved us a lot of time. 

But this playground is still too small for our 30+ chickens. With  chickens pecking all day on an area of 20 square meters (that's the current playground size; the size of coop is not included), my guess is that the grass and insects will disappear within next 7 days. We plan to enlarge chickens' playing area to at least 10 times the current size. We just have to build a new, much longer fence - next task on our To do list. 

Chickens posing for camera.

When it is good to tilt panels to the north.

This is photo of our power plant taken on early morning June 8, 2015:

At first glance there's nothing strange about this picture, but if you know the place, you'll soon notice one strange thing - panels are pointing to the north.
The photo was taken from the east, meaning cardinal directions are as follows:

Logically panels should be tilted to the opposite direction, like on this picture from March this year:

Well, our panels do usually face south, but we noticed that in summer, there are certain times of the day when panels capture most sun when tilted to the north. Those time frames are early morning and late afternoon. We noticed that power generation output can improve by 1-2 kilowatts when panels face the north in the right time of the day.

How to explain it?

The explanation is simple: Position of the sun at sunrise/sunset changes in summer and in winter.  Everyone knows that sun rises in the east and sets in the west. What most people don't notice is that usually it's not due east (exactly 90 degrees on compass) or due west (exactly 270 degrees on compass) -  It's just roughly the east and roughly the west.
It seems that the sun rises due east and sets due west only twice a year (on spring equinox and autumn equinox). On all other days, sun rises somewhat north or south of due east and sets somewhat north or south of due west.

So, when is it north-east and when south-east? When is it north-west and when south-west?

The answer here in Tsukuba, Japan (latitude: about 36 degrees on northern hemisphere), is as follows:

winter sunrise:  south-east
winter sunset:  south-west

summer sunrise: north-east
summer sunset: north-west

This is not a life saving knowledge but it's a fun fact to know! Moreover, now that we're raising chickens under the panels, I go to the power plant early mornings and late afternoons almost everyday. If I'm there anyway, why not change the tilt and improve performance for a few kilowatt hours a day.

Related article: Power generation - performance report (April 24, 2015).

Basic information / 基本情報

Basic information about our project　/ プロジェクトの基本情報

Name: Power plant Oo
名称：　おお発電所

Place: Tsukuba, Ibaraki prefecture, Japan
所在地：　茨城県つくば市

Installed capacity: 
  Installed capacity of inverters　 38.5 kW
  Installed capacity of solar panels　 40.71 kW

設備容量：
  パワコンの容量　　38.5 kW
　太陽光パネルの容量　　40.71kW


Solar panels: 354 panels x 115 W 
太陽光パネル：354枚 x　115 W


Land area: about 1000 m2
設置面積： 約1000平米


Height from ground: 3 m
パネルの地面からの高さ：　3m


Shading rate: about 33%
遮光率： 約33%


Operation start: 27 November 2014
運転開始：2014年11月27日


Design and construction by: Solar Culture, Ceratech Tsukuba
設計・施工： ソーラーカルチャー株式会社、有限会社セラテックつくば


Activities under the panels: Free range chickens / picnics & barbecues
パネル下の土地利用：　鶏の放し飼 ／　バーベキューやピクニック

Chickens flying

It's been a month since our chickens arrived. In the life of a chicken, one month is a long time. It takes humans several years to grow from cute babies into cheeky school-age children. Chickens can do it in a single month.


They are now less cute or fluffy , but they are  stronger and more independent than before. They have impressive wings and can fly!


This is how our chickens looked when they arrived a month ago (end of April):

And these are the same chickens one month later (end of May):

On the picture above, chickens are sitting on a perch that we just finished yesterday (May 31). Perch was an instant success, chickens love it.


Now we're working on a fence outside the coop so that chickens can play on the grass. As they grow bigger, the coop will soon be too small. Picture below shows the inside of the coop (this picture was taken just before finishing the perch yesterday).





That was a quick update.

Chickens arrived!

Two weeks ago 35 newborn chickens arrived! We've been doing our best to protect them from all sorts of chicken enemies. Many of the confirmed enemies are cats. We've noticed great increase in the number of cats around the farm. Cats' favorite place is right in front of the coop, watching what they hope to be their dinner, or breakfast, or lunch, depending on the hour. They are patient, but I'm proud to say that despite their patience, we are winning and there are still 35 chickens in our coop.

Chickens arrived on April 28, 2015, and here they are the following day, just getting used to the big world full of wonders (except for cats). 

They have fluffy bums, cute little wings and huge appetite :)

Power generation - performance report

Our solar sharing power plant has generated a lot of electricity since it started operation 5 months ago - precisely 22 952 kilowatt hours in the period from November 27, 2014 (operation start) to April 24, 2015 (today). That's not bad for an installed capacity of 40 kilowatts.

We use a monitoring service "Solar Monitor" that allows us to check real-time generation status online. Being able to check it anytime anywhere (that is, "anywhere with internet connection") is extremely convenient, and on sunny days it's also quite fun.

Picture below is Solar Monitor screenshot from today April 24, 2015, taken at 17:21. In the circle on the left you can see that the plant was still producing 2 kilowatts of power despite the late hour. That's one of the good things about days getting longer towards summer. From the screen you can see that today a total of 200.4 kWh was generated (for the record, it slightly increased to 201.9 kWh at the end of the day.)

For English explanation check an older screen shot below (click for enlargement):

By the way, the mechanism that allows us to change the panel tilt has been - as expected - a major contribution to performance.

I never noticed it before but the position of sun on the sky is really different in winter and in summer. I do remember learning at elementary school that sun is low in winter and high in summer (therefore shadows are longer in winter and shorter in summer), but I never quite observed the sky and sun to see how different "low" and "high" actually is. Until recently.

In terms of solar power generation, the position of sun has great implications. It means that while in winter you want to lean the panels into very steep tilt (as much as 60 degrees), in summer you want to put them in almost horizontal position (as little as 3 degrees). This greatly affects the amount of electricity produced.

Thanks to the panel adjustment mechanism ("Sora-karu system"), we're doing exactly this - optimizing the tilt every few days (or weeks) according to the seasonal height of the sun.

Graph below shows optimal tilt of solar panels for each month of the year. The graph is for the location of Hachiouji (Western Tokyo), which is some 100 km from here, but it's the same Kanto region so the data roughly apply to our place as well (observation-confirmed). According to this graph, optimal tilt is 60 degrees in January, 34.5 degrees in March, 2.6 in June and 40.8 in October.

You can find the original graph here:

http://www.solar-partners.jp/pv-eco-informations-32764.html

This was a quick performance report.

Our solar power plant construction in 4 minutes

Here's Part 2 of the video summarizing construction of our solar sharing power plant in Tsukuba.  Given that construction was finished in November last year and now it's already April, the video is badly overdue.


There was another video covering the same topic, which I posted in February, but it was so poorly edited that I eventually decided to remake it. This is the result.


Why was making Part 2 so much more difficult than Part 1? Here's a metaphor to explain it. If we compare construction of a power plant to building a house, Part 1 of this video shows how the very building of a house was made - brick walls, window holes, a roof. At first glance it's a complete house, but in fact it's not habitable yet. It has the shape of a house but there's nothing inside. Part 2 shows how the house is equipped with all the basic amenities that make it a real, habitable house: water supply, heating, electricity, furniture.


Part 1 shows the form, Part 2 adds the substance.


The thing is, form is much easier to convey in a video than the substance.


When a building is rising in front of our eyes, it's very comprehensible to our brains. It's interesting to watch.  When some cables are added here and some boxes there, but nothing new is really growing in front of our eyes, it's not very fun to watch.


Anyway I did try my best to convey the substance in Part 2.


Part 2, showing the construction in October and November 2014, is here:

Part 1, showing the construction in August - September 2014, is here:

Enjoy watching and let me know if you have any comments or questions!

Our New To Do List

Our most pressing tasks include:

1. Digging a well

2. Building a chicken coop

3. Planting a hedge

4. Making wooden benches and a signboard

Each task is discussed in detail below.

Our plant in February 2015. 

Photo was taken by our friend Shinozaki-san with a very big and very good camera.

1. Digging a well

Without water, you can't grow plants or keep animals.

We have two options:

A. to dig a shallow (several meters deep) well ourselves

B. to have a deep (50+ meters) well dug by a professional

Digging a well ourselves would be much cheaper and we would get a hands-on experience of digging a well and installing a pump. The demerit is that the water would be of bad quality, given the pesticides used every year on the rice fields around. It would be okay for watering the plants but not for drinking.

Having a deep well dug would be much more expensive and we would get zero practical experience, but we would have clean drinking water.

Access to drinking water might be the single decisive factor - we're now leaning towards having a deep well dug.

2. Building a chicken coop

This is now in progress. It'll take  a few more weeks given our not-so-excellent carpenter skills and the fact that we can work mostly on weekends only.

Nobu and me smiling to Shinozaki-san's camera. 
Thank you, Shinozaki-san, for taking great pictures!

3. Planting a hedge

This is in progress too. The first step is obviously to dig holes around the entire plot. I'm proud to say that hole digging has become my second nature. I've dug many holes of finest quality. If you need to dug a hole or two, ask me. I'm good at it.

The other day I planted ume - plum tree (blooming season is right now) and a sakura tree (to bloom in a few weeks). Sakura and ume are not hedge plants but will definitely add some beauty to the place.

This is plum (All photos below were taken by my iPhone. The difference from the photos above is obvious.):

This is plum with a cool I-don't-care-what-you-do-I'm-not-even-watching-you cat in the background:


This is the same plum in detail:

This is sakura tree:

Don't tell me you can't see it. It's right there. It's going to be a grand sakura tree in about half a century.

4. Building wooden benches and a signboard

Benches - we received a complaint from a visitor that there's no place to sit and rest. Very accurate observation indeed. We've added benches to our to do list.

A signboard - people walking around look bewildered, not knowing what's going on in here. Clearly, a signboard with minimum information about our solar sharing project is necessary. Ideally it will be made of wood and it will include our public Project Name (to be made up) and some curly ornaments in the corner.

I'll inform you about our progress in each area.