Million Solar Roofs Bill Signed into Law

[daestrom]

Oh dear !

You asked a pertinent question ! Shut that man up !

Actually it would need about 150 million 200 watt panels. Simply because
(a) you
don't get the full power output all the time the sun's shining and also
very
little during the winter months and (b) you get no power at all at dawn /
dusk /
night !

OTOH a power station provides its 3GW day in, day out 24/7 !

Why do you rant on about this? The bill doesn't say anything about the
energy production, nor does it compare the energy production of 3 GW of
solar panels versus the energy production of a 3GW power station.

Seems you have confused the power rating of 3GW of solar with the energy
production of a 3GW plant operating 100% capacity factor.


Having 3GW of solar, which of course only produces during sunny days, does
reduce the number of peaking plants needed. While a base-load power plant
may run 24/7, many peaking units only run a very few hours on only some
days. An equivalent 3GW in peaking units would not be needed if 3GW of
solar came on-line to supply the daily peak load.

Since peaking units, such as the ones these solar panels replace, generate
electricity at very high costs, then the solar panels *can* be an economic
option.

Even without subsidies, at $5 / watt over their lifetime, just four hours a
day, that $5 can generate 25kwh or more. That's $0.20/kwh. Peaking units
can run upwards from $0.20/kwh to as high as $1.50/kwh.

Which is 'utter madness', paying $0.20/kwh peak, or $1.50/kwh??

Is solar a good choice for base-load, or complete replacement? No, of
course not. The average price of grid electricity is cheaper. But it *is*
a good replacement for peaking capacity and peak power costs.

But I suppose where you are it rains too much, and you don't have the kind
of mid-day peaking that we have in the US. Maybe you should do some
research about the places you're criticising.

daestrom

 

[SJC]

Folks,
Solar PV still needs a big breakthrough to deliver on the hopes. In the
UK it would cost $63Bn to generate a full GWe-year from current panels.

For a simple comparison of the total costs of complete systems of
Rooftop power, Coal, Gas, Wind, and Nuclear go to
http://cestar.seas.ucla.edu. Their 'papers' file shows my article on
Electricity and my Uranium article which shows how nuclear could run
10,000 reactors for several thousand years.
California, being sunny, could be 3-4 times more cost effective with
Solar PV, bringing the price down to only $20Bn per GWe-year. Nanosolar
may cut this further. There are many excellent ways to use Solar PV,
but replacing power stations is not yet one of them. Carter tried this
in 1980 - I was working in DoE at the time and read all their Solar
docs. - and the technology has not improved greatly since then.

California should go nuclear, not solar.

Brendan McNamara

I came across these solar maps of Europe, thought they were good.

http://re.jrc.cec.eu.int/pvgis/pv/countries/countries-europe.htm

 

[Eeyore]

I came across these solar maps of Europe, thought they were good.
http://re.jrc.cec.eu.int/pvgis/pv/countries/countries-europe.htm

Much obliged for that !

Where I live for example ( near London UK ) it looks like the yearly solar insolation is ~ 980 kWh / m^2..

So 1 m^2 of solar panel @ 10% efficiency would produce 98 kWh annually or an average of 11W.

The value of the electricity produced would be ~ £10 p.a. The cost of a suitable size panel is ~ £500.
http://www.unlimited-power.co.uk/kyocera_solar_panels_pv_modules_uk.html

Actually, these panels say they offer 15% efficeincy so that's £15 worth of electricity produced each year. I'll
give it a miss thanks !

Graham

 

[SJC]

daestrom wrote (inter alia):

Daestrom, did you really mean to say *is* or *may some day be* a good
replacement?

If our current inadequate solar technology could provide reliable peak
power at about 1/8 the cost of alternatives, the solar industry would
be building peaking plants all over the place, and the politicians
would be talking about taxing "Big Sun" instead of throwing out
pointless subsidies.

I suspect the issue comes back to the (un)reliability of that (solar)
peak power. Until we can store energy efficiently, photovoltaics are
probably going to continue to be a very minor contributor -- and of
course, energy storage would push up that $0.20/kWh quite a bit.
Interestingly, once economical energy storage does become available,
then solar will have to compete with baseload nuclear plants running at
a steady rate 24/7 with storage to handle the peaks.

The renewables group went over pumped hydro a while back. Efficiency
can be better than 70%, including losses for evaporation. So if you want to
store energy, just pump water up a hill and make electric on the way down.
However, since PV is not likely to be much more that a few percent of our
power generation and peak summer loads are so high, putting it on the grid
makes the most sense.

 

[daestrom]

daestrom wrote (inter alia):

Daestrom, did you really mean to say *is* or *may some day be* a good
replacement?

If our current inadequate solar technology could provide reliable peak
power at about 1/8 the cost of alternatives, the solar industry would
be building peaking plants all over the place, and the politicians
would be talking about taxing "Big Sun" instead of throwing out
pointless subsidies.

Perhaps I was being overly optimistic. But the *one* place where PV is a
good match and is likely to succeed is in peaking power production in
climates that use a large amount of A/C (such as southern California). This
is one use where the reliability of PV doesn't become a big factor. When
the sun doesn't shine, the A/C load is lower so not as much peaking power is
required.

IMHO, PV will *not* replace any form of base-load for a long time to come.
So I don't agree with those that believe that PV will enable us to shut down
all the coal/nuclear/<fill in undesirable plant type>.

The economics of PV depend strongly on the cost of peaking power plants and
the nature of the load causing the 'peaking'. For example, here in the
northeast, where peaking is caused by both A/C in summer and heating in the
winter, PV could not replace a peaker since PV would not have the
availability needed in winter.

So, while this initiative may work in California to reduce the costs of peak
power, I don't believe it is a 'universal fix' that can be applied
everywhere.

I suspect the issue comes back to the (un)reliability of that (solar)
peak power. Until we can store energy efficiently, photovoltaics are
probably going to continue to be a very minor contributor -- and of
course, energy storage would push up that $0.20/kWh quite a bit.

But if PV is *only* used during A/C load peaks, then storage is not
required. Yes, this limits PV to a small percentage of installed capacity,
and will not replace base-load. I agree with you on that. But for those
special locales that have major peaking caused by major sunshine (A/C
loads), then PV is a good match up.

Interestingly, once economical energy storage does become available,
then solar will have to compete with baseload nuclear plants running at
a steady rate 24/7 with storage to handle the peaks.

IMHO, *that* combination has got a long way to go before it can compete with
coal/nuclear. THAT quantity of storage, quite frankly, is mind-bogglingly
huge. Imagine just two days worth of storage at 1/3 the baseload for
something like the PJM?? At 4:00 AM this morning, PJM's load was still
~65000 MW. So 48 hours worth of storage of 1/3 of that would be 1040 GW-hr
(1.0e12 Joules). And that's just for 2 days, probably not nearly enough.

And sooner or later, someone will realize that storing that much energy,
whether as pumped water or ??? is going to be just a tad dangerous.
Especially if something can trigger its release all at once (such as a dam
failure).

daestrom

 

[daestrom]

Perhaps I was being overly optimistic. But the *one* place where PV is a
good match and is likely to succeed is in peaking power production in
climates that use a large amount of A/C (such as southern California).
This is one use where the reliability of PV doesn't become a big factor.
When the sun doesn't shine, the A/C load is lower so not as much peaking
power is required.

IMHO, PV will *not* replace any form of base-load for a long time to come.
So I don't agree with those that believe that PV will enable us to shut
down all the coal/nuclear/<fill in undesirable plant type>.

The economics of PV depend strongly on the cost of peaking power plants
and the nature of the load causing the 'peaking'. For example, here in
the northeast, where peaking is caused by both A/C in summer and heating
in the winter, PV could not replace a peaker since PV would not have the
availability needed in winter.

So, while this initiative may work in California to reduce the costs of
peak power, I don't believe it is a 'universal fix' that can be applied
everywhere.



But if PV is *only* used during A/C load peaks, then storage is not
required. Yes, this limits PV to a small percentage of installed
capacity, and will not replace base-load. I agree with you on that. But
for those special locales that have major peaking caused by major sunshine
(A/C loads), then PV is a good match up.


IMHO, *that* combination has got a long way to go before it can compete
with coal/nuclear. THAT quantity of storage, quite frankly, is
mind-bogglingly huge. Imagine just two days worth of storage at 1/3 the
baseload for something like the PJM?? At 4:00 AM this morning, PJM's load
was still ~65000 MW. So 48 hours worth of storage of 1/3 of that would be
1040 GW-hr (1.0e12 Joules). And that's just for 2 days, probably not
nearly enough.

Oops, got my sums wrong. 1/3* 65e9*48*3600=3.7e15 Joules.

(if this were pumped storage at 80%, and the elevation difference was 50 m,
that would be ~9e9 m^3 of water. If the reservoir was 20 m deep, that would
be an area of about 478 km^2. Of course it would be broken up into several
storage facilities, but still, that's a *lot* of water )

daestrom

 

[Eeyore]

Why do you rant on about this?

Because it's bollocks ?

The bill doesn't say anything about the
energy production, nor does it compare the energy production of 3 GW of
solar panels versus the energy production of a 3GW power station.

The publicity does.

Seems you have confused the power rating of 3GW of solar with the energy
production of a 3GW plant operating 100% capacity factor.

The media has.

Having 3GW of solar, which of course only produces during sunny days, does
reduce the number of peaking plants needed. While a base-load power plant
may run 24/7, many peaking units only run a very few hours on only some
days. An equivalent 3GW in peaking units would not be needed if 3GW of
solar came on-line to supply the daily peak load.

So why is the publicity comparing it to 3GW of nuclear ?

Since peaking units, such as the ones these solar panels replace, generate
electricity at very high costs, then the solar panels *can* be an economic
option.

Even without subsidies, at $5 / watt over their lifetime, just four hours a
day, that $5 can generate 25kwh or more. That's $0.20/kwh. Peaking units
can run upwards from $0.20/kwh to as high as $1.50/kwh.

Please show your calculations for $0.20/kWh

Graham

 

[Eeyore]

daestrom wrote (inter alia):

Daestrom, did you really mean to say *is* or *may some day be* a good
replacement?

If our current inadequate solar technology could provide reliable peak
power at about 1/8 the cost of alternatives, the solar industry would
be building peaking plants all over the place, and the politicians
would be talking about taxing "Big Sun" instead of throwing out
pointless subsidies.

I suspect the issue comes back to the (un)reliability of that (solar)
peak power. Until we can store energy efficiently, photovoltaics are
probably going to continue to be a very minor contributor -- and of
course, energy storage would push up that $0.20/kWh quite a bit.
Interestingly, once economical energy storage does become available,
then solar will have to compete with baseload nuclear plants running at
a steady rate 24/7 with storage to handle the peaks.

There's also an issue that the peaking generation still has to be there to
provide the power on 'rainy' days and during the darker months!
http://www.powerfromthesun.net/chapter1/images/figure1_6.gif

You simply can't eliminate the need for it.

Graham

 

[Eeyore]

IIRC, several analyses (including at least one by the Department of
Energy) have concluded the US grid could be up to 20-30% PV before
storage technology would be required. That would make it as significant
a contributor as nuclear and natural gas. Even at half that, it would
still be more significant than hydro.

Wind power is vastly more useful.

And *cheap* !

Graham

 

[Eeyore]

Actually, you seem to have missed the word "peak". Nobody is suggesting
that 3 GW of PV will produce as much energy as 3 GW of conventional
baseload capacity.

The publicity I've seen seems to suggest this though.

In reality it will produce between 15% and 25% as
much as 3 GW of conventional baseload plants, but PV is not a baseload
technology so the comparison is a lousy one.

Tell that to the media !

If you compare PV to other
peaking technologies -- that is, compare apples to apples -- it is a
much more favorable comparison (both energy- and cost-wise).


A baseload power station does, provided it's not down for refueling or
maintenance (coal and nuclear plants average 70-80% uptime, though the
best manage 90%).

I rather thought nuclear was way better than that actually ( and probably the others
too ) .

Peaking power plants run much less often -- IIRC,
their capacity factors average something like 40% in the US.


If you do the sums *properly* you'll see that the typical home has more
than enough roof space to provide for its own energy needs with PV.
There are many, many examples of such homes all over the world, you just
have to open your eyes and look for them.

Ok, let's just look at 3GW peak from a million homes.

Each home would have to generate 3kW at peak insolation. A 1 m^2 panel will generate ~
100W at peak insolation in that area using the best technology currently available..

To generate 3kW would require 30 such panels or 30m^2 ( 300 sq ft ! ) and cost ~
$15,000.

So, you get 3kW of peak only electricity at only certain times of the day and in
summer only for an outlay of ~ $15 billion !

Sounds pretty dumb to me !

How much does good insulation and 'solar glass' cost in comparison ? Peanuts.

Graham

 

[Dan Bloomquist]

Perhaps I was being overly optimistic. But the *one* place where PV is
a good match and is likely to succeed is in peaking power production in
climates that use a large amount of A/C (such as southern California)...

It may not be PV, it may be solar thermal electric...

http://ec.europa.eu/energy/res/sectors/solar_thermal_power_en.htm

And it may get better:

http://www.sandia.gov/news-center/news-releases/2004/renew-energy-batt/Stirling.html

The reason, they could get this down to a buck a peak watt in the next
decade. Maybe thin film is on their heals, but that was the story almost
a decade ago. Whichever, it is about that buck a watt threshold.

Best, Dan.

 

[Dan Bloomquist]

The publicity...

So you have been caught at a strawman rant and now you hold up your
strawman???

 

[[email protected]]

I keep stumbling over the obvious follow up -- if it is such a good idea,
why is it not being done on a large scale today? The obvious answer is
that photovoltaics are not economic today, even for those niche uses.

You surmise that as the obvious answer.

There may be many reasons why home PV installations are not more popular.
Panel availability may be one.

Lack of desire to make a financial commitment might be one.

Some lack the financial standing to make the commitment, even if they might
want to buy a PV system.

Some don't believe that it can be true, that it's a scam.

I project the economic viability of my PV system based on avoided energy
costs, which I calculate each month.

PG&E has a announced another rate hike. This one makes the news because it
will affect "tier 2" levels of users, where the previous 10 years have
seen a drop of 2% in the electric rate, from $0.133 to $0.129/kWh.

My electrical usage has not been constrained to those lower tiers. My
pre-solar usage strayed into the higher realms, where 96-current has seen
rate increases of 80-250%.

PV in California looks like a very good deal to me.

It should look like a good deal to my neighbor, who had $500 PG&E bills
last summer, but the high cost of the system required to offset that level
of usage was too much of a commitment.

There is initial negative cash flow in my projections, but that is a burden
that I believe will be well worth while in the long run. Maybe others
don't take a long view of their investments.

 

[Eeyore]

Which would be 12'x20', easily fit on a rooftop.

Eh ?

That's 240 sq ft !

Graham

 

[[email protected]]

From what you describe, many Californians view the economics of home
photovoltaics as being unattractive.

Again, that is what you surmise.
I would say that more find the physical appearance unattractive, and far
more have never given it any thought at all.

Point is, most Californians have had access to capital to pay for the
front end costs of a home photovoltaic system -- if they had wanted to.

Many of the refinancings were to lower monthly payments and take advantage
of reduced rates. Much of the "cash out" was used to pay down credit card
debt, allowing consumers to add more debt. But, I ramble on about
what I perceive, living in the state.

Most Californians clearly did not want to

Most Californians have never even thought about solar.

It is easy to continue buying energy from PG&E. Those at the lower end of
the economic strata have no choice. They don't own a home, or are heavily
leveraged with debt. The energy rates at the lower usage levels haven't
gone up in 10 years, so, if they don't have high energy consumption, they
have no incentive at all to look elsewhere. With the exception of one day
of publicity about the million solar roof plan, there is no seed planted in
the mind of the public.

Those at the higher end of the economic strata don't care about the cost.
They are more concerned with how the PV panels might disrupt the
architecture. There was a posting in this group within the last month or
so from someone who purchased more panels than he needed, beyond what the
net metering agreements would reimburse, so that he could cover one side of
his roof. The glaring aesthetics of a break in the roof design were more
important than the money involved.

 

[Eeyore]

Under the current electricity market rules, payback for my system will
be achieved in eleven years

Show me the sums !

Graham

 

[[email protected]]

In alt.solar.photovoltaic Eeyore

John Ladasky wrote:

Show me the sums !

My June 17, 2006, accounting from PG&E shows -176 kWh peak,
326 kWh off-peak, 150 kWh overall, billing of $-25.77.
The Peak was charged/credited in Tier 1 and Tier 2 at $.29372.
The off-peak was charged/credited in Tier 1 and Tier 2 at $.08664.

My solar system produced 698kWh, so I consumed 848kWh.
Solar was 82% of my energy, over 100% of my bill.

Using non-solar rates, $146.87 avoided PG&E billing for June.

The projection is for me to avoid $1457 in PG&E charges this year.
My projection includes a ROI break even in year 11, at which point the
avoided costs are projected to have risen to $2730. In order for this to
happen, utility rates need to rise 6.5% per annum. If that fails to
happen, and nuclear power does become too cheap to meter, I will have lost
money. On the other hand, the tier 4 rates have gone up 80% in the last 10
years, 22% since I installed my system, so I should come out okay.

 

[daestrom]

daestrom wrote about energy storage:

Point taken. But I was imagining something along the lines of a coal
or nuclear plant operating at a steady output which more or less
bisected the roughly sinusoidal daily demand curve. For about 12
hours, the plant would be feeding any energy it produced in excess of
demand into the storage device, and for about 12 hours the energy
storage would be making up the difference between demand & the plant's
level output.

However, your point is absolutely spot on. Even that would be a lot of
stored energy. And any conceivable store of a lot of reasonably
accessible energy is always going to have an element of risk.

Your broader point about photovoltaics is also a good one --
photovoltaic energy should be able to fill some niche uses, like power
for air conditioning in sunny locations. I keep stumbling over the
obvious follow up -- if it is such a good idea, why is it not being
done on a large scale today? The obvious answer is that photovoltaics
are not economic today, even for those niche uses. The other possible
answer is that photovoltaics really do not fit the niche properly -- in
many sunny areas, the need for air conditioning goes up after the sun
goes down, because of the increase in Relative Humidity as the
temperature drops.

Well, I just have to 'throw a flag on the play' there

Yes, RH rises as outside temperature falls. But the vapor pressure and
latent heat load does not rise just because of that. If you look at a
psychrometric chart and plot the locations of 90% at 80F and 56% at 95F,
you'll find that the actual moisture content in the air is the same
(humidity ratio is still just 0.0707. The amount of moisture that will be
removed in a well-adjusted A/C unit in both cases is about the same.

RH is very deceptive because it is 'relative' to what the air could contain,
and that value changes with temperature as well. Dew-point can be a much
better way to monitor the humidity levels.

I have no beef against photovoltaics -- but it is no panacea; at the
moment it is not even a factor worth considering. If someone like
William Mook can bring the installed cost of photovoltaics down by a
factor of 50, then it begins to look interesting.

Agreed there. He's been doing some interesting work with focusing systems.
That could provide some 'quantum' price reductions (pun intended

daestrom

 

[Eeyore]

Concentrating Photovoltaics have the capacity to reduce the cost of PV
materials by a factor of 500! This is achieved in two ways. The first
reduces parasitic heating by increasing voltage or reducing resistance.
Sater received a patent on the first concept with his innovative VMJ
(vertical multijunction) design. Swanson received a patent on the
second concept with his point junction or back junction design, which
removed a sparse array from the front of the solar cell. Sater's
design allows increases in light intensity by factors of 1,000 and
more. Swanson allows increases in light intensity by factors of more
than 100!

Err........ So a 1 m^2 PV cell can take 500kW of energy input ( without melting
) ?

Graham

 

[daestrom]

There's also an issue that the peaking generation still has to be there to
provide the power on 'rainy' days and during the darker months!
http://www.powerfromthesun.net/chapter1/images/figure1_6.gif

You simply can't eliminate the need for it.

You don't *need* the peaking generation if the major load during the 'peak'
is related to sunshine (i.e. A/C load). The 'peak' in winter time for some
areas is non-existent. Unfortunately for me, in NY, the peak in winter is
about the same as summer, so PV is *not* a winner here.

But in places like southern California, or Florida, where much of the daily
'peak' is caused by A/C, the peak load disappears on rainy days and 'darker
months'. Don't need a lot of peaking generation to supply a load that isn't
there.

So supplying some or a major portion of 'peak' load with PV is a good match,
*in those specific circumstances*. The fact that PV is a lousy fit where
you are is bad luck. But don't be so provincial that you can't see that
other locales are different and can make better use of PV.

daestrom