home battery

Should make for some interesting house fires.

The article doesn't offer any clues as to the technology offered. My wild guess(tm) is that it's something like this water based organic battery:

" that could compete with the National Grid as a power source,"

Someone doesn't understand what "storage" means.

Sylvia.

It's probably going to use Musk's lithium ion batteries.

I suspect that most of the Musk ventures will eventually crash. The Tesla may well go the way of the PT Cruiser. "Everybody who wanted one had one."

Elon Musk has plans to build both battery and solar cell "gigafactories." It's only natural to combine the two into a product for disconnecting from the grid, while also preventing an electric grid meltdown if everybody drove electric cars. Combined markets of ecological fanatics, gadget fanatics, and those without reliable power probably adds up to a large enough early-adopter market to start the business.

Musk is busily making the biggest LiIon factory on the planet, if that's any clue.

Cheers, James Arthur

When I read this I thought about the factor of scale a bit and it occurred to me that while other life in the universe may well be very different from our own because of any number of small differences in their environment. But it is very likely they have the same LiIon batteries because chemistry and physics are universal constants.

So Musk's factory is likely *not* the largest LiIon battery factory in the universe.

Reminds me of a joke... a picture of a city block with a number of pizza shops... 1st one has a sign in the window that says, "Best Pizza in the city"... 2nd one has a large sign in the window that says, "Best Pizza in the State!"... 3rd one has a large sign on top of the building that says, "Best Pizza in the WORLD!!!"... last one has a tiny sign in the window that says, "best pizza on the block"...

Will any of that get me decent Internet access?

But was it a LiIon pizza?

Cheers, James Arthur

People won't disconnect from the grid though, because there will always be times when there's been insufficient sunshine. People will expect to use the grid as backup.

The grid will have to charge a lot to allow people to use it as a generator of last resort, and that will make the economics of solar plus batteries even less attractive than they already are.

Sylvia.

You're probably right but I'm not 100.0% sure. Most of the money for the 5 gigabuck factory is coming from Panasonic, not Tesla Motors. There's nothing to prevent either partner from investing or speculating in alternative technologies. It would seem to me likely that Panasonic might buy up any potentially competitive technologies before they begin to produce product. Better yet, before they're even announced. It might be that Elon Musk just spilled the beans a bit early.

PT Cruiser is a product. Electric cars are a market. It's possible to saturate the sales of a product. Saturating a market is much more difficult. Today's seriously expensive Tesla automobiles will eventually morph into something both affordable and practical. That has to happen because we're running out of things to burn to fuel our civilization. Of all the transportation power alternative, electricity has the best chance of replacing petro power (unless you prefer having a mast and sails sticking out of your vehicle). Some person or company will eventually make it all work. Whether it's Musk and friends will remain to be seen.

attery/

On the other hand, sunlight is free, and we've still got at least one more tenfold increase in solar-cell manufacturing volume in the pipe-line, and t he corresponding halving of the unit price per kilowatt.

Engineers Australia hosted a puff from First Solar last night, and while th e speaker wasn't too explicit about how it worked, he seemed totally convin ced that his firm's 100 MegaWatt solar farms could operate with the existin g grid, and made a great fuss about being able to smoothly ramp up the outp ut into the grid, and ramp it down equally smoothly.

Batteries big enough to carry the grid through the night seems to be some w ay off, but dealing with a small cloud passing across the array of cells se ems to be within reach, not that the speaker had a clue about that (and he was asked about it in question time).

" that could compete with the National Grid as a power source,"

Ramping up and down is helpful, but the real problem the grid has with solar power is that the latter is not reliable, meaning that generating capacity has to be available to cope with a solar power shortfall.

Getting through the night is better than nothing, but the grid also needs to be able to cope with the shortfall that arises when the skies are overcast during the day, meaning that the batteries didn't get charged. In practice, there has to be backup for pretty much the entire solar power generation capacity.

This capacity has a cost even when it's not being used, because of the capital used to construct it.

The real cost of solar power is then the cost of the panels, plus the cost of the batteries, plus the cost of the backup generators.

Sylvia.

Not to mention the cost of the carbon emissions... wait.. what?

A bit of geographic diversity makes it lot more reliable. The First Solar talk made the point that their individual solar farms were already bigger than some small clouds.

Overcast decreases solar power for non-concentrated panels, but doesn't eliminate it. You are always going to have excess capacity in any solar set-up.

You will need back up, but with a smart grid and pre-negotiated rapid-disconnect loads the back-up capacity required is going to be a fraction of regular load, and way less than than all the power all the solar panels could generate at noon on a sunny day.

The capital cost is independent of whether the back-up generators are used or not. You've got to have them, but it doesn't make sense to burn fuel that you have to buy when you don't need to.

In Australia the hydroelectric capacity - what there is of it - is a bit different. You want the dams full at the end of the rainy season, but you may need to run them down to make space for potential flood flows before the next rainy season.

That's the capital cost. The running cost of the system includes the cost of the fuel that you have to burn in the back-up generators.

In reality, the existing generating plant is a lot of the back-up capacity. Gas-turbine-based generating plant is particularly well-suited to the back-up role, as is hydroelectric plant.

I have heard this claim repeated a few hundred times, but never seen any actual test reports supporting it.

I have done some tests with a small panel, measuring both current and voltage simultaneously running into a variable resistor. Adjusting that resistor for maximum voltage and current product to simulate an MPPT. In my observation, the _power_ drop was quite significant when some overcast occurred.

If you just measure the open circuit voltage or only short circuit current, you might incorrectly draw the conclusion that overcast or a small cloud doesn't do much harm. Only by running the panel into an MPPT and measuring the current or voltage, you will get some usable readings.

On a sunny day (Thu, 12 Feb 2015 19:11:46 -0800) it happened John Larkin wrote in :

Quote:

blaming poor sales in China "

More to come?

I think you could well be right. Home batteries are going to have to be incredibly reliable to be worth having. We have had a couple of ex RAF NiFe 200 Ah blocks that were WWII war surplus and they still work.

The NiCads that replaced them were destroyed in no time flat by applying the old NiFe charging SOP to the new batteries. They quickly lost capacity and became useless bricks a very expensive mistake.

NiFe capacity wasn't as good but they were squaddie proof and could stand an astonishing amount of abuse without complaint.

There were actually people who wanted a PT Cruiser?

Try looking in some of the text books that dealt with solar power in the late 1970's. In the UK to a very good approximation the incident energy from direct sunlight and indirect scattered light are about equal and about 10% better for an optimally sloped roof.

Most places get more direct sunshine than the UK too.

Solar PV was largely ignored back then because the cells were both expensive and inefficient. The context was for solar thermal.

Photographic exposure guide EV is another measure:

Which gives a working range of 1:16 for the ratio of full sun on snow to deep shade outdoors.

It is something like an order of magnitude drop (or more) in incident power from full direct sunshine to behind a thick cloud - depending on how much thin cirrus there is about to scatter diffuse light around.

OTOH the cooler PV array performs a bit better.

Agreed that you have to measure incident and converter power.