Solar a viable energy alternative?

[tallgirl]

Well, the Bronze Age started several thousand years ago, so if we've mined half the world's copper, I figure we've got several thousand more years to go

But seriously, just because it's been mined doesn't mean it's disappeared. Metal recycling is a growing business ...

 

[dbuckley]

What an excellent thread.

Is solar a viable energy alternative - in many cases it isn't alternative, 'cos burning coal or gas for electricity generation is using what is stored solar energy...

Mass PV is probably not going to happen in any foreseeable timescale, to a fair number of significant figures 100% of global electricity comes from rotating machinery, and to a bit less precision they are all thermally or hydro powered.

But... there is another approach; use solar energy directly. If you live in a sunny clime, then you can heat water with solar directly, and easily. You can take that hot water, run it through an absorption chiller, and get air conditioning out of it, whilst still having waste heat to keep the pool warm.

I know it's a bit heretical suggesting non-electrical solutions in an electrical forum, but what the heck Here in NZ 47% of the domestic electricity usage is for hot water heating (source), so switching the housing stock to solar hot water would enable a significant reduction in electricity demand.

The real barrier to uptake of solar energy (and indeed many "alternative" forms of electricity generation) is that hydro, nuke and coal power is very very very cheap, and highly available.

To answer an earlier point, the USA is indeed the Saudi Arabia of coal, and has a century of the stuff sitting there, at the current rate of extraction. If the rate of extraction goes up, for example, by converting coal to gasoline for cars, then the number of years the coal will last obviously go down.

 

[dereckbc]

what is the ballpark for dollars per installed watt? I was reading an article which quoted $10 / watt installed (parts and labor for everything, including the frames, etc.)

Well I did some payback estimates sometime ago assuming $5 per watt installed. OK so that was too low. but I am lazy right now and still have the numbers.

A home on average uses 61 kilowatt-hours every 24-hours, so let?s just use 60 KWH to make the math simple.

Now I had to make some assumptions here and assume the home can have net metering from the utility. If not, you are really throwing away a lot more money.

So a bare bones minimum system would be 7.5 KW of solar PV panels to generate 60 KWH per day assuming 8-hours of direct sunlight for each and every day (not going to happen) to generate an average of 60KWH over a 24-hour period so you net 0 from the POCO.

Initial installation cost of the solar PV system is 7500 x $5 = $37,500. Payback time using the extremely high cost of TXU of $.13 per KWH is roughly 13 years. Based on national averages of $.10 per KWH is 17 years. In places like OK where electric rates are $.06 per KWH payback is 29 years.

So now go re-figure using $10 per watt installed and I think you get the idea.

So IMO unless the efficiency of PV radically triples to at least 50% (about 20% at best current, 10 to 15% 25 years ago), and per watt installation cost are cut 50 to 75%, I am not even interested in discussing the option.

 

[PV System]

Sorry about abandoning the thread for a bit. I've been incredibly busy and I spent a week in DC.

As far a PV panels.. As long as the overseas market is willing to pay a premium I don't see anyone dropping the prices soon. I think that production could be ramped up for greater enconomy of scale but I think that no one has made the leap to grater mass production. The common exuse ot the lack of raw materials. I think that is hogwash. several years ago I wanted to develop a product using LCD panels. I could not get anyone to supply them. I was told there was a shortage of raw materials. Now there is a flood of LCD product. The price has lowered to a fraction of what it was. Some venture needs to step up to the plate and start manufacturing the stuff in the masses.

There's a shortage of high grade silicon which is what's used in PV modules. A couple of silicon plants are coming on-line this year which should lower costs of the modules, but the demand for these things keeps going up. In Germany, their net metering setup is so aggressive, that people can install PV systems on their houses, and make substantial money at the end of the year.

PV System, I assume you 'sell' these things for a living??? Alot of the phrases seemed familiar.

In the OP I put it like this...


You know, in the grand sceme of energy production and consumption. At the M/G/T watt level.

While I will agree thet solar can make sense for a relitive few niche market consumers who are willing to sacrifice some of thier consumption to make solar pay off in the residential market. However, most do not fit that niche, or could afford to be part of the million roof initiative, with or without government subsidies that are fading fast. (And a good dose of "feel good", and political currency as an off-set.)

In a duplicate thread on another forum someone posted some interesting math.... Not vouching for accuracy, but this is what I was thinking about when I first posted. Even if solar were only a portion of generation in the US it is still neither economicaly or electricaly viable at this point in time. IMO. Capitol*Real estate*(supply/demand)+maintenance/MWatt output*time= "Can we put wind-generators around the nuke plant?"

ref:

Unless solar makes a huge leap in VA/sq' output, I tend to think that money and resources are better allocated in another 'green' energy source, rather than installing a Model-T on every roof in America. Money would be better spent today putting a 5MW wind turbine on every skyscraper in the country.

I design PV systems for a company that designs and installs them. Am I biased? I try not to be, which is why I'm trying to give out references whenever I can. I doubt I'd have a job if a lot of people and corporations didn't think PV wasn't economically viable.

On a very large scale, I don't think PV will become a viable way of generating power at this time. When electric rates in the US become similar to Europe or Japan, it will be. It will work in certain areas of the country.

I'm assuming you're talking about Steve Fehr's post. That's a lot of math, but his reference values are wrong. For instance, he has 240W/m^2 in the southwest. The solar irradiance used is 1000 W/m^2 but for 4 or 5 hours a day. (Production values of PV systems aren't calculated using solar irradiance, but solar radiation) He has 71 W/m^2 for the northern US. I was out in February with a pyranometer and on a overcast day, I was getting around 300 W/m^2. Steve got these numbers from the Robert Johnston reference. Upon looking at it, Robert doesn't explain how he came up with those numbers; one link is a 404, and the other gives numbered in kwh/m^2/day.

Going back to Steve's post, a lot of his values don't even make sense to me.

"If the south-facing roof of a 200m[super]2[/super] (~2000ft[super]2[/super]) typical house in the US Northeast in winter was covered in a-Si solar panels (assuming no snow):
71W/m[super]2[/super] * 100 m[super]2[/super] * 8.25% * 67% * .85 = 321W (4 houses combined could run a Mr. Coffee)"

200m^2 is a HUGE roof, and covering it with modules gives 321W? On a 41m^2 roof, I can fit an array that would produce about 4500W under real world conditions (and produce about 7100 kwh / year) located in the US northeast.

Wind turbines are great, but always require a lot of work to get the zoning variances and installing those things are rather difficult.

 

[PV System]

I think that the real impediment to people generating solar at their homes is the initial investment as well as the time value of money. When I priced what it would take to go "off the grid" the cost came out to about $50K, minus whatever rebates and tax cuts I'd be eligible for. I think that netted out to about $15K once all was said and done. With my total annual electric bill right at $2,350 per year, I think I can earn almost that much in the stock market on that $15K. Meaning, I could just about pay my entire electric bill if I put $15K into some of the mutual funds I own. So why would I put a bunch of solar panels all over my yard? And if I had to pay all $50K, I could definitely pay my electric bill with a very conservative bond fund with a 4.7% annual return.

Where I think solar becomes viable is on the low end of production, not the "going off the grid" end. I've been looking at having a 13kW Generac installed as backup power and, as I recall, the total cost would be on the order of $10K. For not a lot more, I could install a 1kW array, some number of kWH worth of storage, an inverter and transfer switches. I wouldn't have the same capacity as with the generator, but I would be able to recover some of those costs by reducing what I take from the grid. So, if a 13kW generator is something I really want, I can get to a reasonably close replacement using solar and be able to reduce my electric costs in the process.

I don't know why you would go off the grid. Having a grid interactive inverter is definitely the best way to go (unless you live miles away from the grid and are forced to have an stand alone system). If you want backup power, a generator is a lot cheaper to have and will produce a lot more power than a battery system. The only advantage of battery system is that it's automated. Just make sure that the generator and the PV system are completely isolated from each other.

 

[PV System]

Why ramp up production when low production means Higher prices.. Simple economics.
I 'm not quite convinced that production of wafers for PV need and do cost that much..There have been many products that are produced in limited supply in order to keep prices high.. There are new PV products on the market like the ones from Unisolar These are flexible and can be directly incorperated into the roof system. Reducing the cost of conventional over the roof installations.
I strongly beleive that PV production during the daytime, suppliments the electrical needs when it is most needed at "Peak times"

Simple economics is the supply vs. demand chart. Companies could still produce 150% more solar modules, and while the price would go down, they'd still see better overall profits.

The unisolar thin film is a amorphous silicon which is only about 7% efficient IIRC and requires twice the size of a multi or mono crystalline module.
A correctly sized system will more than adequately provide power to all of your loads and sell some back to the utility. I've seen meters spin backwards in the afternoons in August.

 

[PV System]

stuff

I design grid interactive systems with the occasional battery backup for mostly residential dwellings.

I counted 3 different studies in my paper, and only one payback calculation based on future thin film systems. Here's one from the DOE. This references the same scientists as my previous one, but a much more recent year.

There are some systems out there that are 30 years old; they are few and far between though since PV was very expensive before the 90s.

A lot of your references are based on old data though. Production costs in PV systems have dropped dramatically in the past 10 years (every few months a modular manufacturer announced they've managed to up efficiency a few percent, or they've managed to find a way to use less silicon, etc). Still, all of them seem to be in between 1-8 years.

As you sell these things... I'm sure you would love to pave the world in them, but not so sure about the rest of us

Nuclear fusion would be great and would solve all of our energy needs. We just got to get it to work. Hydro is clean and reliable, but there's few viable spots for it. Wind is clean, but wind turbines are pretty ugly, and require a lot more work (site specific data, zoning variances, etc) to get it installed. Coal's cheap, but has other environmental costs associated with it.

If somebody has another solution, I'm all ears.

 

[PV System]

Hey, I never saw this asked or answered, but for those of y'all who install this stuff, what is the ballpark for dollars per installed watt? I was reading an article which quoted $10 / watt installed (parts and labor for everything, including the frames, etc.) and thought that was entirely absurd, but with all the rebates here in Austin (Austin Energy rebates up to $15K per homeowner at $5K / kW), I wonder if the price hasn't been artificially inflated by the free money running about.

Prices that I've seen are $8-9 a watt. Like everything else, always shop around.

Just looking to open a can of worms.

How many electricians see Solar (PV) as a viable energy alternative?

The most cost efficient and most reliable solar system used to save money would be to install a clothes line and hang your clothes out to dry. The electric dryer uses a substantial amount of electricity.:smile:

I'd agree with this.

 

[robbietan]

Nuclear fusion would be great and would solve all of our energy needs. We just got to get it to work. Hydro is clean and reliable, but there's few viable spots for it. Wind is clean, but wind turbines are pretty ugly, and require a lot more work (site specific data, zoning variances, etc) to get it installed. Coal's cheap, but has other environmental costs associated with it.

If somebody has another solution, I'm all ears.



How about geothermal? I understand that it is like hydro in the sense that few locations have it but what we have here in the Philippines are substantial reserves that somehow make up for the few locations.

 

[dbuckley]

Geothermal works fine, here in NZ 7% of our power comes from geothermal. Of course, NZ is just an ickle country, and that 7% is just a bit over 400MW, or less than half a Yankee nuke (of which you have a fair number)... drop in the ocean...

 

[Bob NH]

Nuclear fusion would be great and would solve all of our energy needs. We just got to get it to work. Hydro is clean and reliable, but there's few viable spots for it. Wind is clean, but wind turbines are pretty ugly, and require a lot more work (site specific data, zoning variances, etc) to get it installed. Coal's cheap, but has other environmental costs associated with it.

If somebody has another solution, I'm all ears.

How about nuclear fission.

The only reason we don't have spent fuel reprocessing, and storage in Nevada, is political. The French generate about 50% of their electricity with nuclear. Nuclear generates power at night, wintertime, and when the wind isn't blowing.

If you analyze a nuclear-electric economy, you find that a lot of the imported oil can be replaced with nuclear power produced by plants that are built by US labor. Liquid hydrocarbon fuels can be reserved for transportation. Natural gas can be used for process feedstock and industrial fuel.

Nuclear power available during off-peak can be used to charge local transportation batteries.

We don't have to wait for fusion. We have to slay the fear and nimby dragons and get on with what works now.

 

[mpross]

nuclear fission/ethanol

nuclear fission/ethanol

Bob,

I am with you on building more nuke plants. This is a great way to supply the base load.

When I worked at a plant here in Iowa (~600 MW BWR), many co-workers said that people are still scared from the TMI accident, or even Chernobyl. Another major concern is of course the spent fuel.

If we got into full-swing production of nuclear reactors, I think that it would also be great to build them to produce hydrogen as a primary function. Someday we could fuel our cars with hydrogen, instead of gasoline.

One more thing for derekbc: I am not being critical, but I am curious about your earlier statement (page 3 on this thread) about ethanol. Do you really think that it is a scam? I hear many people say that it takes more energy to produce ethanol than what you get out of it. Isn't this true for many things we build? Such as a power plant heat cycle.

Since I live in Iowa, I hear all the great things that ethanol is doing for the regional economy, and I also hear the bad too. It is all so politically clouded for me

I wonder what President Hoover would do in today's "energy crisis". He was the great "Engineering President".

Cheers.

Matt

 

[Bob NH]

If we got into full-swing production of nuclear reactors, I think that it would also be great to build them to produce hydrogen as a primary function. Someday we could fuel our cars with hydrogen, instead of gasoline.

Since I live in Iowa, I hear all the great things that ethanol is doing for the regional economy, and I also hear the bad too. It is all so politically clouded for me

I wonder what President Hoover would do in today's "energy crisis". He was the great "Engineering President".

Cheers.

Matt

Ethanol is a scam. It is a political scam to get the farm vote.

Find out how many farmers in Iowa are using ethanol in their tractors? None!

Ethanol has about 70% of the energy content of gasoline, and less than that compared to diesel fuel. But it costs the same as or more than gasoline, and is subsidized by our taxes.

Are there any E-85 pumps in Iowa? How much E-85 is sold in Iowa. I suspect little or none, because I credit the people in Iowa with not being stupid. People got a credit for buying E-85 vehicles, but they burn gasoline in them.

Hydrogen is a great fuel for rockets because it has high energy per pound. But do you notice the size of that big tank on the Space shuttle? It would have very little range for an automobile because the energy density is so low. And there would need to be transportation and storage for a volatile cryogenic fuel.

 

[robbietan]

"Pollute?" How?

If you want net metering, go write your state politicians. Most are very willing to help the solar industry. What state are you in?


Unfortunately, I am in the Philippines, where net metering is not an idea that can be 'intelligently grasped' by the politicians here.

From what I've read, putting solar panels on the land will make that land unsuitable for anything else. like you cant grow crops or build homes due to the heat being generated by the PV. and solar needs more land area per MW than conventional power plants. but thats what opponents will probably say.

With some of the islands here totally off the grid, it is wise to have a study on how solar PVs can help the residents there.

 

[jack horner]

The best "Green Energy" is the good old fashion clothes line. This is the only viable solar alterative I know that will pay for it's self.

 

[winnie]

I like to think about energy as follows:

There is lots of energy all around us, more free (in the thermodynamic sense) energy than we can possibly use. _Just_ looking at solar, the amount of energy delivered by the Sun to the Earth is 500 to 1000x the energy that humans use in the same time period. Then we have all of the energy stored in the rocks in the form of unstable isotopes...tremendous. The total currently stored in the volume of the earth, relative to the cold of space: lots of delta T and useable energy there.

What _costs_, and what we care about, is not the amount of energy available, but instead the cost of gathering it up and putting it into a useable form.

Fossil fuels are simply very inefficient bio-fuels, which themselves are simply inefficient solar power concentrators. When you buy a gallon of gas, you are really buying a whole bunch of solar kWh, _very_ inefficiently processed.

Wind power: again, inefficient solar power. But here again you don't pay for the large solar collector surface. The large surface inefficiently converts solar power into air motion. You pay for the machine that converts the air motion into electricity, and the net result per watt is cheaper than solar power, at least for now.

So called biofuels are again inefficient solar power. Instead of building solar cells, you grow plants, and let them do the processing. You have to pay a farmer to tend the crops, you have to pay for land surface, you have to pay to process the crops, etc. Currently more expensive than fossil fuels, but this has the potential to change if liquid fossil fuels become more expensive, or if the costs of CO2 emission are determined to be significantly greater.

None of these processes delivers more energy than is put in. But for a process to be viable, it must at the least deliver more energy than is used up to gather it.

Regarding Ethanol. It doesn't matter if growing corn to make ethanol is 10% efficient or 1% efficient with regard to the solar energy that goes into the plants; the solar energy is free ( *note). What _does_ matter is how much human labor and how many human gathered resources go into the entire process. If, for example, you had to dump lots of fuel into your tractor, or lots of fertilizer into the soil, then you might find a net loss of 'energy in a form that you care about'. Some people make this claim, and I find it plausible: the total fossil fuel energy that goes into making ethanol is greater than the liquid fuel energy that comes out of the process.

IMHO this is not a problem with biofuels in general, but instead a problem of the development of biofuels in a tremendously subsidized artificial market environment. Remember that the oil that we are talking about replacing _is_ a biofuel, so we have a demonstration that biofuels _can_ work, once we figure them out.

It makes no sense to grow _food grade_ crops, using the necessary fertilizers/pesticides/irrigation/etc., in order to then process a fraction of that crop into fuel.

IMHO bio-ethanol will only become viable if farmers learn to grow crops tuned to ethanol production, and processing is not based on an attempt to subsidize corn farmers, but is instead based upon finding the best bio-source of ethanol.

IMHO bio-diesel is currently more viable than bio-ethanol. Oil producing plants generate a product that is much closer to the final liquid fuel than starch producing plants for fermentation to ethanol. I suspect that the first really viable bio-fuel (meaning one that costs less than the alternatives that it is replacing, without any subsidies) will be bio-diesel from salt water algae. For 'fuel farming' you need to be able to use low grade land, and you need to be able to use low grade water. Corn just doesn't cut it.

Sorry to ramble for so long.

-Jon

*note: when I said that the solar energy is free, I side stepped the point that given two crops, the more efficient one will use less land area to make the same fuel output, so efficiency actually does matter.

 

[dbuckley]

It makes no sense to grow _food grade_ crops, using the necessary fertilizers/pesticides/irrigation/etc., in order to then process a fraction of that crop into fuel.

IMHO bio-ethanol will only become viable if farmers learn to grow crops tuned to ethanol production, and processing is not based on an attempt to subsidize corn farmers, but is instead based upon finding the best bio-source of ethanol.

Well said.

The other issue is, of course, that it is more attractive for farmers to grow crops for oil replacement rather than crops for food, and in extremis, that can be a bit of a problem, food being rather essential.

 

[al hildenbrand]

IMHO bio-ethanol will only become viable if farmers learn to grow crops tuned to ethanol production, and processing is not based on an attempt to subsidize corn farmers, but is instead based upon finding the best bio-source of ethanol.

There is, at least, one interesting alternative to Corn.

Switchgrass, when one figures in all the carbon emissions of both production and consumption of the produced ethanol, is a carbon negative process.

Biofuels derived from low-input high-diversity (LIHD) mixtures of native grassland perennials can provide more usable energy, greater greenhouse gas reductions, and less agrichemical pollution per hectare than can corn grain ethanol or soybean biodiesel. High-diversity grasslands had increasingly higher bioenergy yields that were 238% greater than monoculture yields after a decade. LIHD biofuels are carbon negative because net ecosystem carbon dioxide sequestration (4.4 megagram hectare–1 year–1 of carbon dioxide in soil and roots) exceeds fossil carbon dioxide release during biofuel production (0.32 megagram hectare–1 year–1). Moreover, LIHD biofuels can be produced on agriculturally degraded lands and thus need to neither displace food production nor cause loss of biodiversity via habitat destruction.

 

[petersonra]

So far, no one has come up with any "alternative" energy sources that are even remotely economically feasible on any wide spread basis, except with massive subsidies.

The closest one to being economical is nuclear, and that has political problems that make it a long shot, even though it is probably our best hope for any immediate new energy source.

 

[dbuckley]

You're absolutely correct. Look from the other end of the telescope - if there were a more profitable way of providing energy that could compete with what is there today would the utilities not already be doing it?

The planets storehouse of fossil energy is being burned through, and it cannot go on forever. So at some point, unless something really bizarre happens (like some basic laws of physics being repealed) we are going to have less energy than we have today. You can debate the 'when', but the 'if' is not up for negotiation. Coal is a good (but polluting) stopgap (a century at most?), nuclear as we do it today is of finite life as its raw materials are also a finite resource, but using breeder reactors gets more energy for less input uranium, plus some military use byproducts. Fusion looks like it will always be fifty years away, and experimentally it has yet to achieve an output over it's input. Praise be for hydro, we cant burn the water away - can we?.

Conservation of energy (ie use energy more efficiently, and/or just do less stuff) will push out the when, but there will always be a when.