Million Solar Roofs Bill Signed into Law

[Tim Ward]

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

Yes.
Interestingly, (to me at least) the solar thermal peaking plant at Kramer
Junction nearly went bust when natural gas prices went up a few years ago.
It turns out the steam for the turbines can be generated either by natural
gas, or the solar array.
Apparently, the peak price times the availability of just the solar array is
not profitable -- at least if you're having to guarantee availability.
They're still running, as far as I know, so they must have figured out
something.

Tim Ward

 

[Eeyore]

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.

Quite so.

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.
OK.


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.

I can see the case but even so, the demand for a/c will significantly lag the
availability of PV power due to thermal time constants, so it'll never be a
perfect match.

Graham

 

[Anthony Matonak]

Concentrating Photovoltaics have the capacity to reduce the cost of PV
materials by a factor of 500!

Hasn't so far. Every concentrating PV system developed so far has
wound up costing pretty much the same as any other PV system.

So, for less than $1,000 - a home can be provided for.

I've got $1,000. Where do I buy one?

Anthony

 

[[email protected]]

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.

7%?

Nick

 

[[email protected]]

Baloney.

Please explain to me how you can turn a 100 watt panel into a 5000 watt one
by concentrating.

That's only 50. Piece of cake

Nick

 

[Anthony Matonak]

New Castle Pennsylvania, August 2009.

Ok, I guess I'll have to get back to you in three years.

Anthony

 

[[email protected]]

The cells also must be designed for such concentrations -- the contacts
on a solar cell designed for 1 sun will quickly burn up under the
currents generated by 500X concentration. Other aspects of the cell need
to be redesigned as well, generally those relating to the internal
resistance of the solar cell, but a well designed concentrator cell will
have a higher efficiency at high concentration than under 1 sun, and
typically a higher efficiency than a similar cell optimized for 1 sun.
Problem is, concentrators aren't very effective in areas that see much
cloudy weather -- the clouds scatter the sunlight and prevent it from
being focused.

How about 2-3 suns on a standard panel with water trickling over
the front surface?

Nick

 

[daestrom]

7%?

Nope, my bad. That's the density. I read the wrong scale.

The humidity ratio is 140.2 grains per pound of dry air (0.02 lbm water per
lbm of dry air)

daestrom

 

[daestrom]

Yes.
Interestingly, (to me at least) the solar thermal peaking plant at Kramer
Junction nearly went bust when natural gas prices went up a few years ago.
It turns out the steam for the turbines can be generated either by natural
gas, or the solar array.
Apparently, the peak price times the availability of just the solar array
is
not profitable -- at least if you're having to guarantee availability.
They're still running, as far as I know, so they must have figured out
something.

Yes, when you start looking at day-ahead or further scheduling, the price
you can get for power varies quite a bit between 'firm' and
'unit-contingent' pricing.

Most power purchase agreements don't have a clause of, "well, if it's not
too hot that day because it's cloudy, we'll forgive you not being
available." Depends a lot on the customer and what their loading looks
like.

And don't even get started about the transmission scheduling fees. Bid with
the ISO for some MW's of transmission capacity and then don't use it? No,
you don't get a refund.

For an independent generator, the variability of PV would have a big impact
on the pricing they could get for their power.

daestrom
P.S. But for the 'million PV homes', those issues aren't quite the same.

 

[[email protected]]

Thank you, Clarence, you spared me the trouble. This is pretty much
the same economic analysis that my PV contractor supplied me. However,
looking over your math, I realized that my electrical use rarely
exceeds Tier 2. I never get into Tier 4. So my monetary payback time
will actually be somewhat longer than eleven years.

My usage on the E1 schedule, prior to solar installation, was heavy T3,
some T4, and a little T5 in the summertime. I provided 18 months billing
data to the salesman, which was used to prepare the ROI and system sizing.
After installing the PV, those high tiers are gone.

On a related subject, my energy payback time -- the time it takes for
my PV system to produce the amount of energy that was needed to
manufacture it -- is independent of the billing schedule. And current
studies show that the energy payback time in sunny places like
Australia or California is eight to eleven years.

http://www.hespul.org/Vous-cherchez-des-statsitiques-des.html
"2.1 Energy Pay-Back Time (EPBT)
For rooftop-mounted PV systems, the range of EPBT is between 1.6 and 3.3
years, with the best case in Perth, Australia and the worst case in
Edinburgh, UK."

 

[Jim Baber]

Jim Baber wrote:

[email protected] wrote:




Hardly surprising for 10kW. To generate 10kW year round would take ~ 10,000 sq
ft !

Graham

My 10 kW system has actually produced an average of 46.122 kWh each day
since it was turned on over 3 years ago on the 15th of June 2003 in
Fresno Ca. Fresno is not the best place for solar, but it is better
than some. Fresno has 2 major problems:

1. In the summer it is too hot, in the 76 days since the 15th of
June, our 5 PM temperature has averaged 99.8 F. and this reduces
the power output of solar cells.
2. There were 42 days last winter when we had our infamous "tule fog"
which does not lift at all. I still got some power most days.
There were only 2 days without any production, but none of those
foggy days were over 9.0 kW for the day. That is a long way from
my average.

By the way Graham, I actually have 1625 sq. ft. of solar panels on my
roof, not 10,000. My wife says the astronauts use us as a landmark when
they land at Edwards AFB. I admit it looks like a lot, but the roof
actually has a total of about 4,750 sq. ft. when you have to buy new
shingles for it. I did just before I put the panels up.


--
Jim Baber
Email [email protected]
1350 W Mesa Ave.
Fresno CA, 93711
(559) 435-9068
(559) 905-2204 (Verizon IN cellphone (to other Verizon IN accounts))
See 10kW grid tied solar system at "http://www.baber.org/solarpanels.jpg"
See solar system production data at "http://www.baber.org/solar_status.htm"

 

[Jim Baber]

Jim Baber wrote to mike4ty4's comment:

Well with 3KW you can still run some stuff. It's better than a total
blackout, and this way the homes can contribute power to the grid instead of just
sucking it up.

I wish that were true, but in order to get any of the benefits from the
rebate program, you MUST tie to the grid, and if you are tied to the
grid, your system MUST shut if the grid shuts down. The power companies
will not allow you to continue to generate power when they shut the grid
down, theoretically because of the dangers to their crews. In order to
avoid problems with the power companies and to prevent overloading their
inverters, most of the manufacturers of inverters capable of grid
connection have included automatic shutdown for their inverters when the
inverter senses the loss of the grid power. Overloading would occur,
because not only would you be supplementing the grid (like normally) you
would be trying to feed the entire grid by yourself and Boulder Dam you
aren't.
--

Jim Baber
Email [email protected]
1350 W Mesa Ave.
Fresno CA, 93711
(559) 435-9068
(559) 905-2204 (Verizon IN cellphone (to other Verizon IN accounts))
See 10kW grid tied solar system at "http://www.baber.org/solarpanels.jpg"
See solar system production data at "http://www.baber.org/solar_status.htm"

 

[[email protected]]

I wish that were true, but in order to get any of the benefits from the
rebate program, you MUST tie to the grid, and if you are tied to the
grid, your system MUST shut if the grid shuts down.

Your system needn't shut down. It must stop putting power onto the grid.
What you do behind a properly installed transfer switch is up to you. The
Outback inverter has a built in transfer switch.

 

[Eeyore]

Jim Baber wrote:

My 10 kW system has actually produced an average of 46.122 kWh each day
since it was turned on over 3 years ago on the 15th of June 2003 in
Fresno Ca. Fresno is not the best place for solar, but it is better
than some. Fresno has 2 major problems:

1. In the summer it is too hot, in the 76 days since the 15th of
June, our 5 PM temperature has averaged 99.8 F. and this reduces
the power output of solar cells.
2. There were 42 days last winter when we had our infamous "tule fog"
which does not lift at all. I still got some power most days.
There were only 2 days without any production, but none of those
foggy days were over 9.0 kW for the day. That is a long way from
my average.

By the way Graham, I actually have 1625 sq. ft. of solar panels on my
roof, not 10,000. My wife says the astronauts use us as a landmark when
they land at Edwards AFB. I admit it looks like a lot, but the roof
actually has a total of about 4,750 sq. ft. when you have to buy new
shingles for it. I did just before I put the panels up.

I confess, I was out by one zero on my number.

I'm going to take a stab at your peak power being indeed ~ 10kW using around 160 sq
metres of panels.

Let's say you need ~ 50 panels for 3kW. Let's say you can get those panels for ~
$500 in bulk.

To fit a million homes with that amount of PV would cost $25 billion in solar
panels alone before even factoring in labour and the cost of the grid-tie
inverters. Easily what ? $ 40 bn ? Damn pricey !

Graham

 

[Eeyore]

It does take a lot of energy to produce a 'traditional' PV
(Si) cell, but they do produce more energy during their
life than went into making them

It takes no more than five years for cell to pay off
the energy that went into making it,

Not in most places.

and considering they
have lifespans measured in decades they certainly are
net producers of energy.

Makes more sense than the lame ethanol/biodiesal scams
you trumpet, which *are* energy losers no matter how
you look at it.

How is bio-fuel a net loss ?

Graham

 

[Eeyore]

That is simply not true. You can get an islanding inverter/charger,
such as the SW4048, and hook it up to a battery bank. The batteries
stay fully charged except when the grid is down or disconnected, for
whatever reason.

If you can afford the batteries as well ! That's a collosal expense to cover
yourself during outages.

Graham

 

[Eeyore]

The most optimistic estimates I've seen indicate that if you put X
amount of energy into growing corn, you get at best 1.20 X in chemical
energy, in the form of ethanol.

You haven't looked very far then.

Current best practice ( and why would any new plant use less than that ? ) is a
2:1 return compared to all energy inputs and that's using corn to make ethanol
which is a bad choice anyway.

Also it doesn't take 'gasoline' to grow corn either.

Bio-diesel from rape seed ( canola ) is about 8:1 IIRC. Once again there are
other better candidates like palm oil.

Graham

 

[Anthony Matonak]

I can send you detailed designs of my plant and product.

I can send you detailed designs of my overunity device.
It doesn't work, of course, but I've got the design.

The truth is best verified by the actual product. Not by
predictions, press releases, designs, messages from UFOs
or the reading of entrails.

Anthony

 

[Eeyore]

Not really. A battery-capable inverter/charger costs a bit more than a
pure grid-tie inverter, but we're talking $1k more. And as for the
batteries, they're not terribly expensive. I've got 24 x T-105
batteries, which have enough capacity to let me run totally off-grid, if
I need to. These batteries cost perhaps $60 apiece. That's $1,440. In
a grid-tie situation, where they are only taxed occasionally, during a
grid outage, these batteries ought to last 8 to 10 years (perhaps more).

So we're talking about less than 10% difference in system cost between a
pure grid-tie and a battery-backed-grid-tie system.

If those batteries last 8 years, your annual electricity bill has just increased
by $180 ! Not counting interest etc. Amortising the cost over a similar period,
your increased bill including the battery capable inverter is ~ $300 p.a. more (
again not counting interest ). Sounds damn expensive to me.

Graham

 

[Eeyore]

Sigh. I wasn't saying that ANY gasoline is used in the production of
corn. I was illustrating the energy budget using a common measure of
energy.

It's a very emotive way to say it though and widely abused. The point is that very little oil derived
products need to be sued in bio-ethanol production.

Well, I'm not sure where you're getting your information. Google for
"corn ethanol energy budget" and you'll find things such as

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/06/27/MNG1VDF6EM1.DTL

...reporting on a study at UC Berkeley indicating that "they determined
that ethanol contains 65 percent less usable energy than is consumed in
the process of making it."

Which doesn't even agree with your next example !

...or this University of Nebraska study
(http://webvideo.unl.edu/downloads/WALTERSPRESENTATION.pdf#search="corn ethanol energy budget"
or http://tinyurl.com/khwlh) that indicated that, at best, rain-watered
corn produced ethanol equivalent to 1.4 times its energy input. And the
amount of corn that can be produced without irrigation is rather
limited. Irrigated corn generates a net excess of 30%.

Other studies show up to 2.12:1 IIRC. Despite corn being a poor choice for bio-ethanol. Sugar beet as to be
used in the UK is much better.

I'm not finding anything for "biodiesel energy budget". Can you offer
any references?

It was a while back I saw it. If you think about it though 8:1 sounds reasonable given that its little more
than processed vegetable oil

Graham