Sharp cuts size of storage battery system

By Sosuke Kudo

Sharp Corp has reduced the size of its storage battery system by about 54% and will release it June 1.

It is a storage battery system for indoor use and can be connected to a cloud server. The manufacturer's suggested retail price of the system (a lithium-ion battery and a PV inverter) is ¥2,280,000.

The battery unit measures 520 (W) x 263 (D) x 500mm (H) and weighs about 69 kilograms. Its capacity is 6.5kWh, which is about 35% higher than that of the previous model.

The PV inverter is a hybrid type and also used for solar panels. Its rated input voltage (solar cell) is DC270V. Its rated output is 4.2kW at the time of linkage operation and 1.5kW at the time of stand-alone operation.

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Sounds great and all... but isnt the Tesla Power Wall only $3000 for a similar size?

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Now just get the cost down.

Very technical article though.

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For storage what does 6.5kWh mean ?

6.5 kW for one hour only ?

Tesla import duties will undoubtedly make the local versions more attractive, especially when the local Support aspect comes into play...

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6.5 kWh means a maximum of 6.5 kilograms watts or 6500 watts for a maximum of one hour. Like turning 100 65 watt light bulbs on for one hour.

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In other words, it's not that much if you're trying to run your house after dark based upon one battery.

Also, like other "rechargeable batteries", how long is it's lifetime before the charge retention degrades beyond 6.5 kW/h ? And, is there a discounted replacement policy ?

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@¥2,280,000 I doubt there'll be many private buyers.

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Agreed, and if Corp. buyers exist, one must wonder what the Kickback is, (corruption), or why the are wasting money!

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In other words, it's not that much if you're trying to run your house after dark based upon one battery.

According to the site below, average household consumption in Japan is about 15kWh per day. So it may be enough to get you through the evening. I'm interested to know if these devices can also be charged from the grid and not just from solar panels. If so, it would allow a more even use of the grid, and perhaps allow taking advantage of off-peak electricity rates. Does anyone know?

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"if only it were cheaper""Tesla will save the day" etc. Come on people. Do the math. Look at your electric bill. People have been trying to sell me these systems for years and they RELY on people being greedy, fearful, and stupid. Are you? The last salesman I talked to made a great spiel, but after he was all finished, I just pulled out a calculator and my electric bill and did the math. I told him if he knocked his price in half, I might consider it.

Do I have your attention? OK. Let's take it from the top.

 A battery for my house! What a great idea. If it is about 7 kWh, that should be enough for use during an evening, when the sun is not shining, but electric rates are still high. I can save a lot of money! And it is great for the environment, right?

But let's do the math, just to be sure. 

Let's assume that the rate for electricity is 30 yen per kWh, but I can get electricity after 11 pm at only 10 kWh. Let's also assume that I have solar panels on my roof, and I can sell electricity to the utility for 30 yen per kWh, and that the system is 100% efficient and no taxes, just to make calculations easy. I can get a system for about 300 man, installed, or I can believe Tesla and wait for their system, which will probably be 100 man, installed. 

How will I use it? I will be GREEN and I will charge it up fully during the day with my solar panels and then use that electricity in the early evening. Assuming I can do that every day and assuming that I am not using that electricity for something else during the day, and that I use ALL of that sweet sweet wattage, then I can "save" 7 * 30 = 210 yen per day. Wow! But if I do that, I am "giving up" the money I could have received from selling that power to the utility. So I am not really "saving" anything.

But what if I am not GREEN, and I just charge my battery up every night, and then use that power during the day, every day? Well, that is (7 30) - (7 10) = 140 yen per day. Wow! And I do not even need solar panels at all! So that is a great deal. That is 140 * 30 = 4200 yen per month, or 5 man per year. Easy money! 

Wait. How much does it cost again? Oh yeah, if I believe that Tesla can actually deliver this system to me now, and if I believe that I can actually install it for 100 man, and if the utility will allow it, then it will pay for itself in only 20 years. Well, that is not so great, but, well...

It is worse than that. After 20 years, you will have charged and discharged this battery 7300 times. So as soon as it gets paid off, you will need a new battery!

Is that "fake math?" Maybe if you just use different numbers it will work out, right? Nope. If you get MORE than 30 yen for your solar electricity, you are better off selling that electricity to the utility. If you get ZERO from the utility for your solar electricity, then you still only make 10 man per year from this system, and the payback is 10 years (people in Australia, Tesla's big market, hope to do this). If electricity rates in Japan DOUBLE, then the payback might be 10 years. If the battery were totally free, it would still take you 2 years to pay for the installation cost (I might do this).

And if the battery cost you 300 man, as quoted above? You will be paying that money back for 60 years.  

Go ahead and badmouth Tepco and the other utilities. They do a great job providing you with cheap reliable electricity. If you think they don't, just buy a battery and try it yourself. Good luck with that.

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You can probably do this yourself, but WHAT variables would change the equations above? Lower battery price. Low interest rates. High fees on electricity usage. Cheap night electricity rates. FIT rates going lower than about 15 yen. All of those might make batteries look cheaper by comparison.

One takeaway from the article is how expensive the batteries actually are when you get them from a reputable dealer. Remember that Tesla sells AT A LOSS. I think it is one reason why it is taking so long bringing its products to market. The more they sell, the more they lose. If you want a product that works properly, and which is guaranteed by Japanese standards, it is going to cost a little more.

The business model of a utility is to keep costs as low as possible because it is a natural monopoly. In countries where utilities are horribly mismanaged, you find people looking for alternatives... grasping at straws... hoping for companies like Tesla to save them. It is tragic. A chaotic market wasting huge amounts of capital. The fact that you can't find a way to get electricity much cheaper than you can from your utility is a testament to how well Japanese utilities are doing their job.

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In the math post above, about line 15 is

I can get electricity after 11 pm at only 10 kWh. 

It should be

I can get electricity after 11 pm at only 10 yen per kWh. 

I also note that some asterisks I used as TIMES symbols in the 7 x 30 parts of the equation were deleted. Maybe people can figure that out.

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