Saturday, May 29, 2010

Made in Japan (part 1)

It's not just me in my family that has solar power, no sireee.  It was actually my in-laws that started things off.

My wife is Japanese and her sister lives in the suburbs of Tokyo.  Back in 2008 they installed a grid tied 3.07kWp Sun Vista system by Sharp.  

Sharp call the inverter a "power conditioner" and it has a control and info panel near the utility breaker panel indoors.  It lights up different colours during the day to indicate the power level.  Blue means the system is generating a surplus and is selling electricity to the grid and yellow means it is generating but grid power is being used as well.

The panels are mounted on both sides of the roof but the slopes face sort of east and west so one half of the array is always sub-optimal. The sun doesn't make such a low angle in winter in Tokyo when compared to the south of the UK so the variation of day hours are less extreme and Japanese Autumns and Winters are characterised by clear sunny days (very unlike the UK). In the summer the sun goes mostly directly overhead so it's not such a problem.

Their house is the one at the back of the white one - you can just see the panels on the roof.  The houses are terraced back to back.

The installers mounted the inverter on the outside wall and then ran a wire to the remote control panel inside.
The mains is fed to two meters outside that the utility company installed.  The digital one on the left measures grid power drawn and the old school mechanical one on the right measures solar power sold to the grid.

The remote panel in the house displays an estimate of power being generated as well as the proportion being used or sold and the lifetime kWh. Flicking through the menus you can pull up generating history graphs for the last hour, day, week, or month.

It's about 11am in this shot and it's just started to make a surplus now that we are done with breakfast and have stopped using the kettle.  The sun is a bit hazy today. 

They tend to sell a lot of power during the weekdays when they are out at work but then buy it back at the weekends when they use the air conditioning and clothes dryer.

The whole system is a kit made by Sharp but a local installation company fitted it.

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