Solar panel related question -- help please

[[email protected]]

Thanks for the links. As the 'panel generation factor' is

used to determine the number of solar panels to be used at

a given site, the following is an alternative scheme that

some of us have put together to determine the number of

panels at the same site.

Let us suppose that the electrical parameters for a given

panel are:

Wp=75 Watts

Isc=4.8 A

Voc=21.4 Volt

Im=4.4 A

Vm=16.8 Volt

Active solar panel area AA = 0.605 sq. meter



Define FF = (Vm*Im)/(Voc*Isc) = 0.718



Then, at STP

Efficiency= (Voc*Isc*FF)/(It*AA)*100% = 12.36% (at STP It=1000 Watts per sq. m)



Now let us suppose that the average insolation at the site

is: 500 Watts per sq. m

Actual efficiency at 500 Watts per sq. meter = 12.36*0.5/100.0 = 0.0618 = 6.2 %

Power produced by the single panel=0.062*500*AA(0.605) = 18.75 Watt per hr

So for a 8 hour period(brightest possible sunlight), the total

power generated by the panel = 8*18.75 = 150 Watts per day

So if the total power requirement is ww Watts, the total

number of panels is ww/150



How does the reasoning look like ? Are there any glaring

mistakes ? Please provide your comments

Yeah, if Watt-peak is 75W at 1000 W/m^2, then it will be 37.5 Watt-peak at 500 W/m^2. According to you it is 18.75.

 

[[email protected]]

Back when stimulus money was flowing like water down a rat hole,
I talked to a number of solar vendors.
None of the offerings stood up to simple questions.

I ran into the same issue when back when they were pushing hot water
solar heating systems. The sell was slick but getting real
information was really hard. Lotsa glowing references, though. The
neighbor bought a system (three panels, IIRC). It was off the house
within three years.

The best looking one was a lease program. You saved money on
your electric bill and used that difference to pay the lease and
you came out ahead. No-Brainer...but wait.
Do you base it on actual savings?
NO, it's predetermined assuming you were one of the first 20 people
out of the 10,000 who applied for the subsidy within milliseconds of the
offering. And there was no guarantee that it would be available next year.
Took me half an hour of probing the vague deflected answers
to get to that point.

I'm surprised you got that answer. I had to chase them around the
flag pole many times to figure out what scam they were pulling. Turns
out it was right out of Abbot and Costello (13 donuts).

I asked for the free site audit...they must have lost my application.

Never trust the numbers from anyone who's trying to sell you something.

Or politicians (same thing, I suppose).

Talking to actual owners is way better...if you can find them.
But that's not foolproof. The placebo effect is very strong.
When I had my house weatherized, I noticed a great savings in energy.
Over time, as I settled back into my old ways, the savings decreased.
And I actually measured it. Most people are just guessing and feel
better if their guesses support their decisions.

There were a lot of weatherization subsidies.
I'm sure it's better for the planet, and the children, but based on the
payback period, I'd probably not have done it on my own dime.

Same for solar. It's great if you can get someone else to pay for it.

As you point out above, can you be sure they're going to be so willing
to pay for it, for the *expected* life of the system. Note that the
seller is getting his money up-front. He's not waiting for 20 years.

 

[rickman]

So, if you really want to get his attention, just name 1 mw/sq-mm as
one Jeroen. He will either consider it an honor, or assault you
violently at your next meeting.

Full disclosure and confession: I still use micro micro Farads. Old
habits are difficult to break.

Jeff, I don't care what they say about you here, I think you're alright.

BTW, I am a real habit sort of guy, but I gave up uuF a long time ago.
I *am* just recently getting used to nF however.

Rick

 

[Don Lancaster]

Snip


Also use the proper derating factor on performance statistics gleaned
from any solar system owner, that spent his hard earned money.

Mikek

About 1500 watts per square meter max in the Arizona desert.
1000 watts per square meter less clouds and tracking typical elsewhere.
About 3 to 5 watthours max daily per panel watt.

Translates to 80 watts peak per square panel meter at the synchronous
inverter terminals at best.

Not one NET watthour of solar electricity has EVER been produced.
Taken as a total to date, pv is simply a gasoline destroying scam.

Easily proven by equating current dimes and kilowatt hours. As the
power utilities clearly do.

Net pv energy breakeven can be anticipated eight to ten years after
the panel price drops under twenty five cents per peak watt. The best
utility pricing today is three times this, the best consumer over ten
times.

But prices are presently in free fall.

A consumer synchronous inverter typically today will consume 150
percent or more of the value of the electricity sent through it.

For a while there, the number of pv and other solar bankruptcies was
approaching one per day.

The usual mistake made by epsilon minuses claiming net pv payback is
counting subsidies as a 1X asset, rather than as a 5X liability that
includes the "iceberg effect" of true collection and distribution costs.

Additional details at http://www.tinaja.com/etsamp1.shtml

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[[email protected]]

Jeff Liebermann wrote:







A VERY, VERY interesting paper! But, it seems that they have the antenna

fabrication pretty well worked out, but no work on the MIM diodes has

been done. So, no practical device has been built or tested.



Jon

Actually, Garret Moddell and his Idaho group has been very active
in the MIM field. In fact, I think a 2011 or 2010 paper examines
the issue and concludes that using existing nano antenna with MIM diodes work in tapping energy from the far infra-red part of the spectrum, at near infra-red, Mother Nature takes over, and skin
and effects become so dominant that rectification is very poor.

 

[[email protected]]

Yeah, if Watt-peak is 75W at 1000 W/m^2, then it will be 37.5 Watt-peak at 500 W/m^2. According to you it is 18.75.

The factor of 2 arises from the FF, and my main
question is whether it is valid to include it in
the computation.

 

[[email protected]]

The factor of 2 arises from the FF, and my main

question is whether it is valid to include it in

the computation.

Insofar as sizing the panels for the required output, it has nothing to do with anything. That kind of thing is only important for MPP trackers. Same goes for the unnecessary inclusion of the active area. What could be simpler than multiplying the daily irradiation energy density per m^2 by the rated panel output power per unit of that irradiation density (1000 w/m^2)? That's all you need.

 

[[email protected]]

About 1500 watts per square meter max in the Arizona desert.

1000 watts per square meter less clouds and tracking typical elsewhere.

About 3 to 5 watthours max daily per panel watt.



Translates to 80 watts peak per square panel meter at the synchronous

inverter terminals at best.



Not one NET watthour of solar electricity has EVER been produced.

Taken as a total to date, pv is simply a gasoline destroying scam.



Easily proven by equating current dimes and kilowatt hours. As the

power utilities clearly do.



Net pv energy breakeven can be anticipated eight to ten years after

the panel price drops under twenty five cents per peak watt. The best

utility pricing today is three times this, the best consumer over ten

times.



But prices are presently in free fall.



A consumer synchronous inverter typically today will consume 150

percent or more of the value of the electricity sent through it.



For a while there, the number of pv and other solar bankruptcies was

approaching one per day.



The usual mistake made by epsilon minuses claiming net pv payback is

counting subsidies as a 1X asset, rather than as a 5X liability that

includes the "iceberg effect" of true collection and distribution costs.



Additional details at http://www.tinaja.com/etsamp1.shtml



--

Many thanks,



Don Lancaster voice phone: (928)428-4073

Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552

rss: http://www.tinaja.com/whtnu.xml email: [email protected]



Please visit my GURU's LAIR web site at http://www.tinaja.com

The technology for distributed energy generation of all types, including fossil fuels, are all antiquated failures. The solar mirror farms that focus huge amounts of solar thermal to a concentrator boiler to power steam driveturbines which power electrical generators is a viable technology. This gets piped at HVDC onto the grid. The grid distributes the energy- no emissions of any kind and vast amounts of existing infrastructure remain in place.We could have built up a few TWatts of capacity by now with all the money wasted on tax credits.
PV solar still has its uses, like powering instrumentation in remote locations, satellites, and small scale auxilliary stuff like pumps and fans in other systems.

 

[JW]

And so on. Google gropers. Much like Jesus among the lepers, there's far
too many of them.

[...]

The factor of 2 arises from the FF, and my main
question is whether it is valid to include it in
the computation.

Welcome to my killfile, Fucko. Say hello to that other thimble-wit, Fred
Bloggs.

 

[amdx]

The technology for distributed energy generation of all types, including fossil fuels, are all antiquated failures.
The solar mirror farms that focus huge amounts of solar thermal to a concentrator boiler to power steam drive turbines
which power electrical generators is a viable technology. This gets piped at HVDC onto the grid.
The grid distributes the energy- no emissions of any kind and vast amounts of existing infrastructure remain in place.
We could have built up a few TWatts of capacity by now with all the money wasted on tax credits.
PV solar still has its uses, like powering instrumentation in remote locations, satellites, and small scale
auxiliary stuff like pumps and fans in other systems.

Here in Florida, many of the billboards have several solar panels
installed. I talked to an installer and ask about batteries, because I
never see any from the ground. He said yes they are there. I wonder
about payback and whether these are subsidized with hard working tax
payer money.
Mikek

 

[Ralph Barone]

A particular solar panel product will specify the output power , Pout,
measured at standard test conditions (STC) which are defined as 1000
W/m^2, 25oC cell temperature, and 1.5 Atm air pressure.

Hey Fred, where the heck is normal air pressure 1.5 atm?

 

[[email protected]]

Hey Fred, where the heck is normal air pressure 1.5 atm?

http://www.greenrhinoenergy.com/solar/radiation/spectra.php

It's not air pressure- it is atmospheres- to account for the actual spectrum of the light reaching the surface after absorption effects of the atmosphere.

 

[[email protected]]

Hey Fred, where the heck is normal air pressure 1.5 atm?

http://rredc.nrel.gov/solar/spectra/am1.5/

 

[[email protected]]

And so on. Google gropers. Much like Jesus among the lepers, there's far

too many of them.

I'm sure Google is absolutely devastated by your disapproval of their practices. After all, what has Google ever done compared to your intellectual prowess.

 

[rickman]

If you are off-grid, then you have to deal with energy STORAGE,
usually batteries, and that can become a substantial task.
Years ago, when the last Diesel submarine fleet was being downsized,
vast arrays of Ni-Cd batteries were available cheaply, but that was a couple
decades ago.

NiCd batteries have a seriously short life compared to the rest of the
devices in solar. Lead acid may be less advanced technologically, but
they have a long lifetime if you don't deep cycle them. I worked for
the railroad once and they had lead acid batteries in service for over
twenty years! Of course they were running at very low duty cycles as
backup for signals, etc.

Also, where can you get electricity for 1 cent / KWh? In a lot of the
US it is now closer to 10 Cents/KWh.

Not only is $0.01 not a realistic price, even $0.10 is pretty low if you
consider all the costs. Including transmission and distribution, I pay
some $0.15/kWh in the eastern US and that doesn't include the misc other
fees on my bill. With that it is closer to $0.20/kWh. So if I were to
go off the grid, this full amount is my reference point for comparison.

Also, here in Maryland the state mandates the utility buys back customer
generated power, but that is only at the generated cost which is
currently < $0.10/kWh. I guess the utility then gets to bill
transmission cost to other customers for my juice they are selling to
them. This would be pure profit.

Rick

 

[Les Cargill]

The sun works much better down in Florida than it does up here in the
pacific northwest....

You know, even oil companies get subsidies from the government from
our hard working tax payer money.

No, they don't as it turns out.Where applicable, they get depletion
allowances as do all mining concerns, and they get machine
depreciation. There's nothing special about any of it.

 

[amdx]

If you pay attention you'll see that a lot of those billboards are
installed where there is no electric service available at 120/240. Some
have no medium voltage distribution lines nearby, as well.

I don't see it that way. I live in a small city with a couple of
four lane roads with plenty of business's and billboards. The power they
need is here.
All I'm aware of are retrofits, not new installations.

BTW, where do live that they have no electric service available?

Mikek

 

[mike]

I don't see it that way. I live in a small city with a couple of four
lane roads with plenty of business's and billboards. The power they need
is here.
All I'm aware of are retrofits, not new installations.

BTW, where do live that they have no electric service available?

Mikek

There's no electrical service in your front yard.

Take the school zone radar speed detector.
Probably costs $200 for that solar panel and batteries to run it.
Now, call up the city and ask how much to dig up the street to
tap into that power pole across the street.
Then call the utility and ask the initial and recurring costs
to get 2 watts of power to your detector.
Then call up accounting and ask what it costs to add another account
to the payment schedule.
Solar is a no-brainer for low-power projects
when you have no viable/cost-effective
SYSTEM alternatives.

 

[mike]

Not only is $0.01 not a realistic price, even $0.10 is pretty low if you
consider all the costs. Including transmission and distribution, I pay
some $0.15/kWh in the eastern US and that doesn't include the misc other
fees on my bill. With that it is closer to $0.20/kWh. So if I were to go
off the grid, this full amount is my reference point for comparison.

That's an interesting point. The distribution costs didn't change much
when you left the grid. So, the rest of us have to pay more.
It's easy to say that one person leaving the grid is good.
It's easy to say that everybody leaving the grid is good.
All that space in the transition is a bitch.

 

[[email protected]]

I don't see it that way. I live in a small city with a couple of
four lane roads with plenty of business's and billboards. The power they
need is here.
All I'm aware of are retrofits, not new installations.

BTW, where do live that they have no electric service available?

I former cow-orker is off-grid in the back sticks of Vermont (90% of
the state). He has a PV/battery system with a generator for backup. A
friend of my uncle's had a generator/battery system because he was
10mi. from "the grid". His house was a beautiful place on the
Menominee River in Wisconsin. There are places where it's just not
practical to tie to the grid; as expensive as the alternatives are,
tying to the grid is even more expensive.