home battery

[Martin Brown]

On 13/02/2015 04:51, John Larkin wrote:

On Thu, 12 Feb 2015 19:51:25 -0800, Jeff Liebermann <jeffl@cruzio.com
wrote:

On Thu, 12 Feb 2015 19:11:46 -0800, John Larkin
jlarkin@highlandtechnology.com> wrote:

http://www.theregister.co.uk/2015/02/12/musk_to_unveil_home_storage_battery/

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:
https://news.usc.edu/64612/usc-scientists-plug-in-to-a-new-battery-thats-cheap-clean-rechargeable-and-organic/

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

http://www.forbes.com/sites/uciliawang/2013/11/05/tesla-considers-building-the-worlds-biggest-lithium-ion-battery-factory/

http://www.nbcnews.com/tech/innovation/elon-musk-wants-tesla-batteries-power-homes-n305071

I suspect that most of the Musk ventures will eventually crash. The

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.

Tesla may well go the way of the PT Cruiser. "Everybody who wanted one
had one."

There were actually people who wanted a PT Cruiser?

--
Regards,
Martin Brown

 

[Martin Brown]

On 13/02/2015 09:41, upsidedown@downunder.com wrote:

On Fri, 13 Feb 2015 00:47:39 -0800 (PST), Bill Sloman
bill.sloman@gmail.com> wrote:

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.

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

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:

http://en.wikipedia.org/wiki/Exposure_value#Tabulated_exposure_values

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

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.

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.

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.

Agreed that you have to measure incident and converter power.

--
Regards,
Martin Brown

 

I put in a solar array and pay nothing for grid power.

How much did you pay for the solar install?

How much did you used to pay for grid power?

How long will it take to get your money back?

Thats the economic view point.
I could ask the same questions about energy investment.


Mark

 

On Fri, 13 Feb 2015 11:19:08 +0000, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:

On 13/02/2015 09:41, upsidedown@downunder.com wrote:
On Fri, 13 Feb 2015 00:47:39 -0800 (PST), Bill Sloman
bill.sloman@gmail.com> wrote:

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.

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

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:

http://en.wikipedia.org/wiki/Exposure_value#Tabulated_exposure_values

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

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.

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.

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.

Agreed that you have to measure incident and converter power.

Each photographic stop represents a power of 2, so 1 or 2 stops below
direct sun light is more or less useless.

It should also be noted that PV panels generate electricity only when
the photon has sufficient energy. Photons below this may increase the
bolometric (total energy) of the sky, but only photons above the
threshold will actually produce electricity.

 

On Fri, 13 Feb 2015 05:12:21 -0800 (PST), Bill Sloman
<bill.sloman@gmail.com> wrote:

On Friday, 13 February 2015 23:39:34 UTC+11, upsid...@downunder.com wrote:
On Fri, 13 Feb 2015 11:19:08 +0000, Martin Brown
|||newspam|||@nezumi.demon.co.uk> wrote:

On 13/02/2015 09:41, upsidedown@downunder.com wrote:
On Fri, 13 Feb 2015 00:47:39 -0800 (PST), Bill Sloman
bill.sloman@gmail.com> wrote:

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.

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

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:

http://en.wikipedia.org/wiki/Exposure_value#Tabulated_exposure_values

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

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.

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.

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.

Agreed that you have to measure incident and converter power.

Each photographic stop represents a power of 2, so 1 or 2 stops below
direct sun light is more or less useless.

It should also be noted that PV panels generate electricity only when
the photon has sufficient energy. Photons below this may increase the
bolometric (total energy) of the sky, but only photons above the
threshold will actually produce electricity.

Clouds don't change the spectrum of the incident light - they just reflect and scatter it.
Thick cloud reduces the local albedo so that most of the energy gets scattered back into space.
It looks dark from underneath, but white from above.

And hence useless for any PV applications.

 

On Fri, 13 Feb 2015 05:07:44 -0800 (PST), Bill Sloman
<bill.sloman@gmail.com> wrote:

On Friday, 13 February 2015 20:41:26 UTC+11, upsid...@downunder.com wrote:
On Fri, 13 Feb 2015 00:47:39 -0800 (PST), Bill Sloman
bill.sloman@gmail.com> wrote:

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.

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.

I didn't say that overcast didn't reduce non-concentrated solar panel output, I just said that it didn't eliminate it.

What is "eliminating" ? 0.1 %, 1 % or 10 % ?

Syliva Else was claiming that "there has to be backup for pretty much the entire
solar power generation capacity" which is nuts.

The worst case scenario is about that.

The peak solar power generating capacity - at noon on a sunny day -
is going to be way higher than the network could absorb

Anyone designing such idiotic systems deserve to be shot.

(at least not without some power storage system - either pumped or batteries -
which currently seems to be much too expensive to be practical).

 

[DecadentLinuxUserNumeroUn]

On Fri, 13 Feb 2015 13:58:33 -0500, rickman wrote:

He is right about there being more than enough coal to keep the fires
burning for a very long time. Fuel is not so much the problem as the
oxidizer to burn it with. Well, let me remove my tongue from my mouth
and say it's really not even the lack of enough oxygen, it's the issue
of the waste products. Burn coal and you get many, many pollutants in
the air such as SO2, NOx, Mercury, other heavy metals, arsenic,
hydrocarons, CO and lets not forget.... CO2!

Yes, burning coal is a major source of that world famous greenhouse gas
CO2. We will never see even a few percent of the total carbon resources
burned because the damage to the environment will become so obvious that
even the modern day dinosaurs will be able to see the asteroid coming
and change our course. The only question is will we be able to turn the
pilot wheel fast enough to avoid the iceberg (mixing my metaphors a bit
here)?

I still say that Yellowstone will "heal" us all.

We deserve it too.

 

[John Larkin]

On Thu, 12 Feb 2015 23:15:29 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Thu, 12 Feb 2015 20:51:22 -0800, John Larkin
jlarkin@highlandtechnology.com> wrote:

On Thu, 12 Feb 2015 19:51:25 -0800, Jeff Liebermann <jeffl@cruzio.com
wrote:

On Thu, 12 Feb 2015 19:11:46 -0800, John Larkin
jlarkin@highlandtechnology.com> wrote:

http://www.theregister.co.uk/2015/02/12/musk_to_unveil_home_storage_battery/

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:
https://news.usc.edu/64612/usc-scientists-plug-in-to-a-new-battery-thats-cheap-clean-rechargeable-and-organic/

It's probably going to use Musk's lithium ion batteries.
http://www.forbes.com/sites/uciliawang/2013/11/05/tesla-considers-building-the-worlds-biggest-lithium-ion-battery-factory/
http://www.nbcnews.com/tech/innovation/elon-musk-wants-tesla-batteries-power-homes-n305071

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.

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."

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.

There's gigatons of coal, oil, and natural gas, enough to last
hundreds of years.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John S]

On 2/13/2015 8:11 AM, John Larkin wrote:

There's gigatons of coal, oil, and natural gas, enough to last
hundreds of years.

How do you know this, John? Do you have a *reliable* reference for this
assertion?

 

[John Larkin]

On Fri, 13 Feb 2015 08:39:32 -0600, John S <Sophi.2@invalid.org>
wrote:

On 2/13/2015 8:11 AM, John Larkin wrote:

There's gigatons of coal, oil, and natural gas, enough to last
hundreds of years.

How do you know this, John? Do you have a *reliable* reference for this
assertion?

Look it up. There's tons of info online.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[whit3rd]

On Friday, February 13, 2015 at 10:32:07 AM UTC-8, John Larkin wrote:

How efficient is a solar panel under a cloud, that's covered in two
feet of snow? How about a thermal concentrator?

Mount your solar panel vertically, aimed south, and the snow just reflects
more sunlight onto it; you don't get less power, you get more.
This is a winter question, right? With the sun low in the sky?

 

[Harry D]

"John Larkin" wrote in message
news:4rqqda56ajmpl4gcqfa0m20fob6p395u4a@4ax.com...


http://www.theregister.co.uk/2015/02/12/musk_to_unveil_home_storage_battery/



--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

I put in a solar array and pay nothing for grid power. I would love to have
a Tesla car, safest in the world, and use it's battery to back up my fridge
when the grid goes down. Turns out that EV batteries are good for home grid
backup.
Just my $.02.
Cheers, Harry

 

I'm an avid reader of Home Power magazine.
http://www.homepower.com
There's one technology which is never even mentioned, probably because
it doesn't work. That's charging a battery pile from commercial AC
power during off peak hours, and using the stored energy during peak
hours, in order to prevent power consumption from going into the more
expensive utility billing tiers. I've tinkered with the numbers for
this using common lead-calcium stationary batteries and it's far from
economical. I haven't bothered to do this for Li-Ion for the same
reason that you don't see Li-Ion UPS power supplies on the market. A
100% fully charged Li-Ion battery has a reduced life expectancy.

if you have time of use pricing, you can save a lot of money by use of simple timers and common sense to schedule the use of hot water heater/dryer/air cond...etc to off peak time.

No expensive batteries and inverters are needed.

I am waiting for time of use pricing to be offered in my area. They already took away the heating rate and I'm already paying for the smart meter.

Mark

 

[John Larkin]

On Fri, 13 Feb 2015 15:47:27 +0200, upsidedown@downunder.com wrote:

On Fri, 13 Feb 2015 05:07:44 -0800 (PST), Bill Sloman
bill.sloman@gmail.com> wrote:

On Friday, 13 February 2015 20:41:26 UTC+11, upsid...@downunder.com wrote:
On Fri, 13 Feb 2015 00:47:39 -0800 (PST), Bill Sloman
bill.sloman@gmail.com> wrote:

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.

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.

I didn't say that overcast didn't reduce non-concentrated solar panel output, I just said that it didn't eliminate it.

What is "eliminating" ? 0.1 %, 1 % or 10 % ?

Syliva Else was claiming that "there has to be backup for pretty much the entire
solar power generation capacity" which is nuts.

The worst case scenario is about that.

Like the US Northeast is experiencing a lot lately. Blizzards that
cover entire states, just when you need a lot of energy to keep from
freezing to death.

http://www.usatoday.com/story/weather/2015/02/13/blizzard-snowstorm-boston-new-england/23348961/

How efficient is a solar panel under a cloud, that's covered in two
feet of snow? How about a thermal concentrator?




--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Fri, 13 Feb 2015 10:09:06 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Thu, 12 Feb 2015 19:11:46 -0800) it happened John Larkin
jlarkin@highlandtechnology.com> wrote in
4rqqda56ajmpl4gcqfa0m20fob6p395u4a@4ax.com>:


http://www.theregister.co.uk/2015/02/12/musk_to_unveil_home_storage_battery/

Quote:
"During the earnings call the company revealed it made a loss of $108m (Ł71m) in its fourth quarter,
blaming poor sales in China
"

More to come?

There's a beautiful Tesla charging station in the parking lot of the
Safeway in Truckee. I've never seen a car charging there. Shoppers
park their gasoline cars in the charging slots when things are busy.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

On Friday, February 13, 2015 at 3:47:43 AM UTC-5, Bill Sloman wrote:

On Friday, 13 February 2015 18:49:12 UTC+11, Sylvia Else wrote:
On 13/02/2015 6:17 PM, Bill Sloman wrote:
On Friday, 13 February 2015 17:42:59 UTC+11, Sylvia Else wrote:
On 13/02/2015 4:09 PM, Kevin McMurtrie wrote:
In article <ck5b0cFru6hU1@mid.individual.net>, Sylvia Else
sylvia@not.at.this.address> wrote:

On 13/02/2015 2:11 PM, John Larkin wrote:

http://www.theregister.co.uk/2015/02/12/musk_to_unveil_home_storage_battery/






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

Someone doesn't understand what "storage" means.

Sylvia.

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

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.

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 the corresponding halving of the unit price per
kilowatt.

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

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.

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.

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

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.

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.

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

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.

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.

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.

--
Bill Sloman, Sydney

As a point of reference, my area's averaging about one sunny day per three
cloudy this winter. (We had gone ~six weeks without seeing the sun, then got
a lucky streak.)

'Cloudy' days produce 2% to 5% output on my polycrystalline reference panel,
compared to full sun.

Cheers,
James Arthur

 

[Jeff Liebermann]

On Fri, 13 Feb 2015 06:11:07 -0800, John Larkin
<jlarkin@highlandtechnology.com> wrote:

There's gigatons of coal, oil, and natural gas, enough to last
hundreds of years.

Perception is everything. I still remember the alarmist headlines
during the 1973-74 "energy crisis" proclaiming that we're running out
of literally everything. There were predictions that we'll run out of
gasoline by the next century. None of that happened, but the effect
on the economy and public buying habits were spectacular.

It might be true that there are gigatons of various fuels in the
ground (I have my doubts), but there are factors that might discourage
or prevent the use of these fuels even if they were cheap and
plentiful. Fears of global warming might put petroleum fuel
consumption in an unfavorable position, as enforced by higher fuel
taxes for research and CO2 mitigation. OPEC has provided a splendid
example of inflexible commodity pricing by constricting the supply in
order to maintain the prices. They're currently also doing a great
job of temporarily lowering fuel prices until all the companies based
on fracking and shale oil begin to fail. Fuel in the ground is
useless unless all the middle men and governments between you and the
fuel are cooperative.

Meanwhile, alternative fuels and sources have the potential for
creating billionaires out of their proponents. All that's needed is
to create the perception that petro fuels are evil, destructive,
depleted, etc, and the alternative fuels and sources will appear quite
attractive (by comparison).

Right now, such alternatives are in the early adopters stage, where
consumers will buy into the new technologies for any imaginable reason
except cost effectiveness. For example, an 80 year old semi-retired
friend just blew $26,000 on grid tied solar installation in a marginal
location. Based on my extrapolation of his current output and
assuming a constant rate of increase in electric power rates, I
calculated that he would break even in about 25 years. However, he
proclaimed that this was of no concern, since the purpose of his
"investment" in solar was a social and political statement that
somehow cleansed his conscience from a lifetime burning the evil
fossil fuels. I had much the same reaction when I calculated the
alleged savings of buying a hybrid automobile.

Eventually, we'll run out of such early adopters and need to deal with
the economic reality of alternative fuels. Of course, there will be
cost reductions and efficiency improvements. My guess(tm) is that
they will not be sufficient to make electric powered transportation
cost competitive with petro fuels. The only obvious alternative will
be to make petro fuels more expensive, which is what seems to be
happening. That also saves the inconvenience of running out of fuels
before the alternatives are ready.

I'm an avid reader of Home Power magazine.
<http://www.homepower.com>
There's one technology which is never even mentioned, probably because
it doesn't work. That's charging a battery pile from commercial AC
power during off peak hours, and using the stored energy during peak
hours, in order to prevent power consumption from going into the more
expensive utility billing tiers. I've tinkered with the numbers for
this using common lead-calcium stationary batteries and it's far from
economical. I haven't bothered to do this for Li-Ion for the same
reason that you don't see Li-Ion UPS power supplies on the market. A
100% fully charged Li-Ion battery has a reduced life expectancy.
<http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries>
Reading between the lines, methinks this is what Elon Musk might be
proposing for his home storage battery. Unless I missed some new
battery technology, it won't work. That's one reason why I guessed
that it might be a different battery technology.

I guess we wait for the official announcement and proposal.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Friday, February 13, 2015 at 1:32:07 PM UTC-5, John Larkin wrote:

Like the US Northeast is experiencing a lot lately. Blizzards that
cover entire states, just when you need a lot of energy to keep from
freezing to death.

http://www.usatoday.com/story/weather/2015/02/13/blizzard-snowstorm-boston-new-england/23348961/

How efficient is a solar panel under a cloud, that's covered in two
feet of snow? How about a thermal concentrator?

My off-grid buddy has ~10kW(?) in PV panels, and uses resistive heaters to
slide off the snow. Has to, otherwise he goes 'dark.'

Even with that, and a prime location, he stills runs a generator ~1,000hrs
a year, maintains two generators, and yes, they fail. The oil-change
interval on at least one of them is 100hrs, about twice a month.

Cheers,
James Arthur

 

[rickman]

On 2/13/2015 9:39 AM, John S wrote:

On 2/13/2015 8:11 AM, John Larkin wrote:

There's gigatons of coal, oil, and natural gas, enough to last
hundreds of years.

How do you know this, John? Do you have a *reliable* reference for this
assertion?

He is right about there being more than enough coal to keep the fires
burning for a very long time. Fuel is not so much the problem as the
oxidizer to burn it with. Well, let me remove my tongue from my mouth
and say it's really not even the lack of enough oxygen, it's the issue
of the waste products. Burn coal and you get many, many pollutants in
the air such as SO2, NOx, Mercury, other heavy metals, arsenic,
hydrocarons, CO and lets not forget.... CO2!

Yes, burning coal is a major source of that world famous greenhouse gas
CO2. We will never see even a few percent of the total carbon resources
burned because the damage to the environment will become so obvious that
even the modern day dinosaurs will be able to see the asteroid coming
and change our course. The only question is will we be able to turn the
pilot wheel fast enough to avoid the iceberg (mixing my metaphors a bit
here)?

--

Rick

 

On Friday, February 13, 2015 at 6:50:56 PM UTC-5, John Larkin wrote:

On Fri, 13 Feb 2015 15:36:04 -0800 (PST), dagmargoo...@yahoo.com
wrote:

As a point of reference, my area's averaging about one sunny day per three
cloudy this winter. (We had gone ~six weeks without seeing the sun, then got
a lucky streak.)

'Cloudy' days produce 2% to 5% output on my polycrystalline reference panel,
compared to full sun.


A guy was installing panels next door, and tried to sell me, too. He
said that power output was down about 50% on cloudy days.

I just spoke to my off-grid pal. I was mistaken about having him having
embedded heaters. He has to scrape his panels with an ice-scraper on an
extension pole. Once they're partly clear, they heat up on their own.
(I must've been thinking of someone else regarding the heaters.)

He's on a mountain top in the dry southwest--perfect solar country. He quoted
some actual output numbers from the past week--his thin-film panels make 10%
on cloudy days, not 50%. (That's real-life data.)

Cheers,
James Arthur