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Japan Aiming for 30% of Households to Have Solar Panels by 2030

Kyodo. The Japanese government will aim for 30% of all households to have solar panels installed by 2030 as part of its efforts to fight global warming. Under the target, the number of solar-powered households would increase to 14 million from the current 400,000, and the capacity of such generation would expand 30-fold from the current 1.3 million kilowatts.

The target will be incorporated into a program for innovative technologies to cut greenhouse gas emissions to be announced at the Group of Eight summit in July at the Lake Toya resort area of Hokkaido, they said.

In a bid to develop new, low-cost solar panels so ordinary households can install them, the government plans to convene experts from home and abroad to set up an international research institution in fiscal 2008, and is seeking 2 billion yen [US$18 million] for the project in the fiscal 2008 budget, they said.



Good for them. Democratizes the energy suppliers. In the event of an outage, parts of the system may still be able to get power counting on how it is set up. At least those will panels will be able run partially.

Best of all, it guarentees a demand for panels, which should support R&D in the technology and production of solar panels especially in Japan as it has in Germany.


__Installing solar panels on that scale will decrease urban solar albedo. Unmitigated, this will increase the urban heat island phenomenon. Most urban citizens will welcome this during the cold months (winter). Conversely, few will receive hotter summer days with cheers, due to higher heat stroke numbers, greater AC usage thus higher energy usage, etc. Backing the photovoltaic panels with pipes to heat tap water for warm/hot water (preheat) purposes is one option.


Cont from above:
....Backing the photovoltaic panels with pipes to heat tap water for warm/hot water (preheat) purposes (when the temp reaches 70F/21C and above) is one option.



no, not really...
solar panels are no different than what any plain roof does in terms of heat transfer/heat absorption; no PV city albedo don't do nothing, au contraire, it warms the city, solar panels or no solar panels, unless you do what the greeks and peoples of the mediterranean do for centuries and paint their entire houses including the roof white, then yes, you have a cooling effect in the summer and a beautifully looking city; the idea of combining DSHW w/ PV has been around for many years, but no succesful implementation yet; I support it...cheers and ... eat organic


Solar panels are not IR reflectors. They get warm and need to stay cooler for more efficient operation. This is one reason that they are mounted off the roof surface, for air flow.



neither is the roof an IR reflector, unless you do what tigersaurus suggests; what's your point ?

both roof or PV heat up to about the same temperature 170F in a warm day; PV efficiency decreases with higher temps & type of PV used, the roof doesn't matter how hot it gets; therefore solar panels are installed a few inches over the roof to allow a little cooling, the albedo effect is the same, do you know what the 1st TD law is? if solar shingles are used they cannot be raised, so again, what's your point ?


I don't know about Japan, but in the western US most residential roofs I see are already dark (composition shingle, mostly these days), and get very hot under the summer sun. I don't see how covering one heat-absorbing cover with another will make much difference to albedo. I agree that adding solar panels to roofs which are currently reflective may increase heat absorption locally, but I doubt this will make a significant difference across a city.



Keep your insults to yourself or get banned. I was stating fact and you start insulting. Stop it or be banned...last warning.


While many rooftops are black, there are others that are white, metallic, or other high albedo (higher than black) color. Google Earth or Google Map (satellite) Tokyo and NYC.

Additionally, a building's facade (southern facade is preferable) is another location to install photovoltaic panels. Several recent residential mid/high rises and office skyscrapers in NYC have them.

Don't get me wrong, I am in favor of installing solar energy systems in urban areas. The grid here often strains (and sometimes fails) under the electric demand on a hot summer day. However, there are negatives that must be recognized, quantified, and neutralized.

One strategy to fulfill the 30% household coverage and reduce the heat island effect is to target residential (and offer relevant information-including economic benefits and financing-to owners/residents of) structures with low albedo roofs to install the panels and/or increase the roof's reflectivity (including green roofs). Such installations will require structural inspections. In some cases repainting with a silvery paint the roof may be the only option.

All this is of course in flux as technology is rapidly advancing. As photovoltaic thin films mature, then affordable, lightweight, acceptably efficient options become a reality. This will enable buildings with lower structural margins, that can't bear silicon cell panel's weight and wind loads AND a heavy snow and ice load, to collect solar energy.


So where does the energy come from to output from the panel? I think I'd rather sit under one on a hot day than in the full sun.
The Solar hot water however I'd be inclined to place in the full sun. ?
Call me simple but..



"So where does the energy come from to output from the panel?"

From converting (solar) photons into electrons (in motion through electric wires). However, all photovoltaics are not 100% efficient, and thus also generate heat.

"I think I'd rather sit under one on a hot day than in the full sun."
In certain cases, such as at a bus stand, I agree. OTOH, one must consider the loads induced by installing a canopy to shade a spot on the roof, or porch, or driveway. In typhoon/hurricane/severe thunderstorm/winter storm prone areas, wind loads are not to be taken lightly.

These are exciting times. Nonetheless, feasibility and suitability are paramount. Strategies and technologies in contemplation and development have the potential to significantly change our environment for the better. The opposite is also true.

Take the example of many thin-film solar cells. Some are made of toxic and/or rare elements. A recycling program, to recover the elements and ensure proper disposal, and R&D in alternative materials and technologies for solar cells are necessary parallel developments.


My comment was meant as somewhat cheeky, the previous postings arguing the point around albedo (as that portion of energy rejection). My point would be that while some reflection or transmittance, both important to the solar panel designer is a factor- viz dual layer panels where the second layer picks up the unabsorbed spectrum as second tier and the specialized glass designs, of low reflectivity and a secondary short wave re- reflection as these wavelengths reflect back from the photovoltaic. breath.
The point is that if the 30% effifiency benchmark is here, then 30% of that energy is shifted via the wire to wherever. Does it matter wether it is /isnt used under that roof?
I just dont see an increase in albedo.
This reminds me of the paint the deserts white to increase albedo. But where does that leave the darkest rainforest converting all that E to C as wood.
If solar panels are seen as viable to install it will be most efficient to see them installed on new buildings so both the power and shelter aspects are most advantaged. The buildings can use the panel as the primary weather protection and the panels on specifically designed buildings will give maximised outputs. Maybe water cooled panels will have a place if the technology supports this.
I whole heartedly agree that E(lectonics) waste disposal is a serious problem and that it needs to be a given that the proper disposal and recycling of such is the only way to survive these highly toxic materials. This applies equally to the mining of these materials but is not often discussed in the same forum.
The rare elements, many once not so rare are another imperitave that best practice be developed if the future technologies are to become conducive to life on the planet.
every journey starts with the first step.


Bear in mind that every watt of solar panel installed is going to displace 3 watts of peak-hours heat output at the powerplants spread throughout the city...


They're talking about installing 40 gigawatts of solar panels! And I thought the Germans had forced up the price of PV too far....

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