This is a typical Japanese house with solar system installed. The owner Mr. Tani installed a solar hot water system 5 years ago on the south-facing roof of his house at 0.8M yen. The water tank holds 200 liters of hot water. The water tank looks like a small box on the roof.

Details of A, B, C, D, E.
 

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Mr. Tani installed 34 pieces of 1m X 1m solar photovoltaic (PV) panels on the East and West facing roof in Dec 1997 at 4M yen, of which 1/3 was subsidized by the government. The maximum output was expected to be 3.4kW. (For comparison: A small Honda is about 1M yen). There was no battery in the solar PV system. If the batteries and the related equipment were installed, the installation price would increase by 50%. The following photos show the PV electricity equipment installed inside the house to regulate and distribute the solar electricity generated.
 
 

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Can you see the solar PV power generated (in kW), kW consumed in the house, kW sold to the government, recorded by the meter at the moment of photo-taking. The following charts showing the electricity amount (in kW-Hour) generated/used/bought/sold by Mr. Tani in 6 different days in March, April, May 1998. The surplus solar electricity not used in the house was fed into the electricity utility supply network. The purchase price from the utility, and the selling price to the utility were the same.
 

Chart 1 -  March, 98

Chart 2 -  April, 98

Chart 3 -  May1, 98

Chart 4 -  May3, 98

Chart 5-  May15, 98

Chart 6 - May28, 98

Do you know what the numbers at the right hand side of the first three charts are?
According to Mr. Tani, the payback period for the solar PV system would be about 20-25 years.
NREL has a web site on feeding solar PV electricity into utility grids, which is http://www.nrel.gov/research/pv/pv_util.html .

After enjoying the solar technical visit, the guests from Hong Kong, Dr. Sam Hui, and K P Cheung, were taken by surprise with the subsequent extremely professionally presented traditional Japanese tea ceremony and wood-fragrancy test ceremony hosted by Mrs. Tani, assisted by Miss Tani.
 

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Also, Mr. Tani installed a flexible toilet/shower room in his house.
 
 

The wash hand basin is extended close to the foldable door, so that the water closet at the rear wall can be used.	A closer look at the wash hand basin with the combined hot and cold water mixing unit for the basin and for the shower.	The wash hand basin is swung to stand above the water closet, leaving an area for a person to take a shower.
The water closet is seen behind the wash hand basin	Mr. Tani also installed an advanced toilet having the following features: low flush selection when urine or other non-soil flushing is operated  high flush selection for flushing soil content  water used for washing hands will drain to the flushing cistern  a toilet seat with an electric warmer  a deordorising system which absorbs foul air  remote-controlled bidet like "washlet" giving warm water spray for gentle, natural hygienic cleasings.  ( similar product reference: http://www.totousa.com/ )

Can you guess the dimensions of the room?

OTHER RELATED PHOTOS:

Outside Mr. Tani's house, there is a road sloping up on the east side of the house.

Looking towards south is another house beyond the balcony at the upper storey of Mr. Tani's house.

The north side of the house is separated by a clean and neat lane from the next house.

Looking at ground level from this balcony is Mr. Tani's car squeezed into a very tight parking space

There is plantation on the west side of the house.

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