Parking lot sunshades

[Morris Minor]

This is a good idea IMO - keeping parking lots cool by shading them with solar panels. It should save on gasoline too - no need to run the a/c at max for 30 minutes to cool a sunbaked car interior.
http://www.businessweek.com/investing/green_business/archives/2008/05/sun_shades_cool.html/topic:Alternative%20Energy



Thoughts?

[Middle_Path]

Don't think that would work here in Texas where we could use something like that. Those panels would probably be messed up in a year or two from hail damage. Then you've got generic debris like bird poop or tree leaves that would need to be cleaned off as another expense. It just wouldn't work....for now.

[AutobahnSHO]

Ha americans are so dumb you could even charge them $.50 to park under them!! 

[Morris Minor]

Yeah - I was wondering about the maintenance - keeping them clean etc.

[Morris Minor]

Ha americans are so dumb you could even charge them $.50 to park under them!! 

At the parking lots around airports it's very common to charge customers more to park under cover.

[Tave]

Don't think that would work here in Texas where we could use something like that. Those panels would probably be messed up in a year or two from hail damage. Then you've got generic debris like bird poop or tree leaves that would need to be cleaned off as another expense. It just wouldn't work....for now.

That isn't specific to a parking lot. It's something all solar panels everywhere have to withstand.

[MrH]

I still don't understand why people think solar panels are going somewhere.  The advances made in solar panels since their existence is minimal at best.  There has yet to be a giant break through in solar panel technology in 20 years.  They still aren't cost effective within 15 years.

[cawimmer430]

Ha americans are so dumb you could even charge them $.50 to park under them!!  

Everyone can see that Lexus is just a Toyota: except Americans it seems.  

[Tave]

I still don't understand why people think solar panels are going somewhere.  The advances made in solar panels since their existence is minimal at best.  There has yet to be a giant break through in solar panel technology in 20 years.  They still aren't cost effective within 15 years.

Try 2 years for the newest generation.

Improvements in the technology are comming at us from every side: flexible panels, transparent/translucent panels, lighter panels, high-tech materials, better batteries, better system designs, better return, etc...

The industry is definitely growing and evolving.

[93JC]

There's an interesting article about solar power in September's National Geographic. One point the author made regarding the slow advancements in technology has been the IT industry: photovoltaics have been passed over for microprocessors. Computers have followed Moore's law, doubling their speed every few years, but because photovoltaics have largely been dismissed and ignored since the late '70s they haven't progressed at the same rate.

[Rupert]

Shade of any kind is a good idea in a parking lot.

[565]

There's an interesting article about solar power in September's National Geographic. One point the author made regarding the slow advancements in technology has been the IT industry: photovoltaics have been passed over for microprocessors. Computers have followed Moore's law, doubling their speed every few years, but because photovoltaics have largely been dismissed and ignored since the late '70s they haven't progressed at the same rate.

As someone that worked on a solar racing team, I don't believe that statement is true.

First off Moore's law doesn't really refer to speed originally.  It refers to the complexity of systems (density) at a certain cost.  Basically put, transistor count will double for microchips for a unit time.  Applied to solar cells, it would say complexity will double as well.  If anything, that seems to hold somewhat true for solar power as well.  Our systems got around twice as complex in a similar span of time, if not in parts at least in sophistication.

The difference is that for microchips a more direct relationship exists between complexity and performance.  A transistor is a transistor, no matter how small. Doubling your complexity in the same size and thus your transistor count will drastically improve your performance.  Solar cells and solar cell technology are not the same way, a solar cell has an absolute upper limit at 100% efficency.  The most you can hope for is to asymptotically approach 100% in a nonexistant perfect world.  If solar panels increased in performance at an exponential rate like computer chips, we'd exceed 100% efficiency pretty quickly. 

People believe that just because solar panels look like computer chips, that they must have the same properties.  That is not true.  If anything, solar panels are similar to any other forms of energy conversion, like engines.  The gasoline engine has been in development for over a century and has had billions and billons of dollars thrown at it.  It certainly has not gone up exponentially in performance.  If we started with 1 horsepower with the Benz patent motorwagon 124 years ago, and doubled every 2 years according to Moore's law we'd be driving cars with around 4.6x10^18 hp today.  Converted to watts that's about 3.5x10^21 watts.  Interestingly that would be 20,000 times more power than the Earth receives from the sun in total.  Also you would only need 100,000 cars (about the number of cars in a town) to equal the total output of the sun.

Also interestingly it doesn't take that much actual money and investiment for something to follow Moore's law especially if there hasn't been alot of work on it before.  When Moore's law was established in the 60's, computer hardware companies like Intel were very small.  Alot of the earliest work was done at academic institutions.  Ironically while we put together our solar car in the basement in college, we were just down the hall from the room that housed the ENIAC computer.

[MrH]

Try 2 years for the newest generation.

Improvements in the technology are comming at us from every side: flexible panels, transparent/translucent panels, lighter panels, high-tech materials, better batteries, better system designs, better return, etc...

The industry is definitely growing and evolving.

Nearly everything you listed doesn't make them more efficient.  Making them lighter, and flexible may make them more usable, but it doesn't make them anymore efficient.  They haven't improved much in terms of efficiency in quite awhile, and still aren't cost effective within 20 years usually.  Even if we were to design solar panels to be 100% efficient, they wouldn't deliver all that much in terms of output.

EDIT:  I'd like to point out while motor performance hasn't followed Moore's law, they've definitely come a long way in terms of efficiency.  The goal with engine development isn't the same as it is with transistor development, and shouldn't be compared.

[Tave]

still aren't cost effective within 20 years usually.

Uh, I think you need to check the ROI again.

Also, doesn't cost have as much an influence on that equation as efficiency?

[GoCougs]

Again, interesting, but the economics in a free market will prevent it; solar panels, the conversion electronics and power storage. At the heart of it all is the density of the power of the sun is abysmal.

The only solar power method I've seen that it remotely financially viable are the huge mirror farms that concentrate the sun's rays onto a collector of some sort, thereby heating a working fluid (oil, liquid sodium, etc., that is able to hold heat during the night) or runs a Sterling engine, which in turn boils water and runs a steam turbine. In this method there are no solar panels and no batteries, but they only work (or seem to, they're all big) on a big scale and thus are out in the middle of nowhere.

[Tave]

Again, interesting, but the economics in a free market will prevent it; solar panels, the conversion electronics and power storage.  

Solar panel production has been doubling every 2 years since 2002. It's the world's fastest growing energy sector.

[Onslaught]

Everyone can see that Lexus is just a Toyota: except Americans it seems.  

We can see it. We just think that Toyota's are good.

[GoCougs]

Solar panel production has been doubling every 2 years since 2002. It's the world's fastest growing energy sector.

Maybe so, but the sun's power density is extremely low (relative to fossil, nuclear, hydro).

[MrH]

Uh, I think you need to check the ROI again.

Also, doesn't cost have as much an influence on that equation as efficiency?

Maybe it wasn't clear what I meant.  Yes, cost does have just as much of an influence.  What I meant by "still aren't cost effective within 20 years usually" is that they usually don't cover pay for themselves until after 20 years of use.  That's if they work that entire time without needing repair as well.

Solar panel production has been doubling every 2 years since 2002. It's the world's fastest growing energy sector.

That doesn't really mean anything.  Hydrogen fuel cells and ethanol were the wave of the future and the fastest growing, new propulsion method for cars just a couple of years ago.  Now look at the market.  Everyone is yappin about, and dumping money into electric cars.

Just because money is being spent on something, doesn't make it more feasible necessarily.

[Rupert]

That doesn't really mean anything.  Hydrogen fuel cells and ethanol were the wave of the future and the fastest growing, new propulsion method for cars just a couple of years ago.  Now look at the market.  Everyone is yappin about, and dumping money into electric cars.

Just because money is being spent on something, doesn't make it more feasible necessarily.

That wasn't his point. The statement was a reply to Cougs, who said that the free market would never support solar panels. Tave said that it already has.

[GoCougs]

That wasn't his point. The statement was a reply to Cougs, who said that the free market would never support solar panels. Tave said that it already has.

You'll find either government money or altruistic intent behind said panel "market."

Solar panels simply cannot compete on an objective $ basis with fossil, nuclear or hydro, without the government taking significant measures.

[MrH]

That wasn't his point. The statement was a reply to Cougs, who said that the free market would never support solar panels. Tave said that it already has.

Ah, my bad.

But still, short term growth in a largely government funded field doesn't mean long term support from the free market.  I think ethanol and fuel cells are perfect examples of this.  I was simply pointing out that short term growth doesn't give any indication of what's a viable and worth-while energy source.

[Galaxy]

You'll find either government money or altruistic intent behind said panel "market."

Solar panels simply cannot compete on an objective $ basis with fossil, nuclear or hydro, without the government taking significant measures.

Prices for solar panels are coming down rapidly.

Nuclear power would be unaffordable if the government did not underwrite the insurance. No one would take the risk.

[Galaxy]

Maybe so, but the sun's power density is extremely low (relative to fossil, nuclear, hydro).

On average the total solar energy absorbed by the earth?s surface is 3,850,000 exajoules per year. That is almost twich as much as the estimated energy that can be harvested from coal, oil, natrual gas and uranium. Even if the estimates are off by 100, 200, 300% it does not matter.

Currently modern solar panels can convert around 150-200W per square meter, from solar energy measuring 1000W. That might not be very efficient but it means that most houses have a roof surface big enough to sustain them. While the systems do pay pay off within a few years the upfront costs that need to be payed at once are of course a problem.

[Tave]

What I meant by "still aren't cost effective within 20 years usually" is that they usually don't cover pay for themselves until after 20 years of use.  

I know what you meant, but you're just flat out wrong. The ROI on new solar panels is much shorter than 20 years.

Google "thin film photovoltaic"


And no, I still don't think you're getting it.

If a solar panel costs half of what it did yesterday, but returns the same amount of energy, it has just cut it's ROI in half.

Part of this is simple economies of scale. As more and more panels are produced, it will become (it already has become) cheaper to produce them.

Google "crystalline silicon PV prices"

Of course you have to factor-in any subsidies, but even without it is obvious that costs are comming down.

[r0tor]

PJM (aka the "grid" operator for the middle atlantic states and actually biggest in the world) did a study regarding "green" power a little while ago and their effects to the power grid.  The summary of that is solar and wind power has a capacity factor of about 20% (meaning produces power only 20% of the time) and when renewable energy reaches about 25-30% of the total generation on the grid - the elecric grid will basically collapse do the the unreliability of renewables.

....the 20% capacity factor of solar and wind is also roughly verified by experiences of my company as well...

[Galaxy]

PJM (aka the "grid" operator for the middle atlantic states and actually biggest in the world) did a study regarding "green" power a little while ago and their effects to the power grid.  The summary of that is solar and wind power has a capacity factor of about 20% (meaning produces power only 20% of the time) and when renewable energy reaches about 25-30% of the total generation on the grid - the elecric grid will basically collapse do the the unreliability of renewables.

....the 20% capacity factor of solar and wind is also roughly verified by experiences of my company as well...

The fluctuations are a problem but they can be solved. First of all the bigger the grid, the less fluctuations become a problem. A good example of this is the pan european grid, with the exception of a few remote villages and perhaps some Islands, every household dnd business is part of the pan european grid and every utility operator from Italy to Finnland, every wind turbine and solar panel feeds into the grid. If the wind is not blowing in Germany it probably is in Sweden or perhaps the sun is shining in Spain. In Germany itself excess wind power is stored in pump storage hydroplants, you take a efficiency hit but it works. If there is a shortage then gas (natrual or biogas) fed turbines can react much more effectively then difficult to scale coal and nuclear plants. Germany was at 14% renewable energy mix in 2007, probably closer to 16% now.

For the planned Desertec project in Africa the fluctuations become irrelevant. The solar thermal plants use the sun light to boil water (thank the Lord for steam power  ) at the same time part of the solar energy is stored in the form of liquified salt. At night the salt becomes the heat source for creating steam. Since the solar input in north africa is fairly consistant the needed amount of infrastructure becomes quite easy to calculate.


It is a good thing that the PJM company was not put in charge of the Apollo project. They  probably would have said it can not be done.

[Galaxy]

Germany was at 14% renewable energy mix in 2007, probably closer to 16% now.

Disclaimer: That is in regard to electricity production. When you look at total energy consumption (including automobiles) it was at 6.7% in 2007.

[r0tor]

It is a good thing that the PJM company was not put in charge of the Apollo project. They  probably would have said it can not be done.

PJM is not a company, they are the regulators of the largest power grid in the world at roughly 150,000 gigawatts of generation and able to send out or pull in another 100,000 gigawatts from neighboring grids... it puts europes grid to shame.  At 16%, Germany has not reached the tipping point yet. 

Think about it this way - the power being generated at any given time must equal the power being consumed as there is very little energy storage on the grids.  A large portion of the power is created by fossil fuel fired steam plants.  These plants can have start-up times ranging from 18hrs to 1.5 days to reach peak output from a cold start.  Even nuclear plants can have relatively long ramp up rates depending on their design.  The fastest ramp rates are natural gas fired gas turbines and combined cycle plants with startup times ranging in a couple hours - however due to their operating costs they are not very abundant.  Solar power can be completely lost in several minutes and for several days if a storm system blows thru. 

Given that solar and wind plants only are producing power 20-25% of the time, it should be rather obvious you can't count on them producing more the ~25% of the power grids power.

[Raza]

You'll find either government money or altruistic intent behind said panel "market."

Solar panels simply cannot compete on an objective $ basis with fossil, nuclear or hydro, without the government taking significant measures.

Currently....

Because, you know, technology never improves.  Although this typewriter I'm using is pretty fancy.