sailor What is the current efficiency of PV cells & their storage systems? What potential is there for improvement? Where lies the problem?
Of all the major PV companies out there, NONE of them claim that solar electirc is a replacement for other forms of energy.
Working for a manufacturer of Photo-Voltaic modules, I loudly acknowledge the following facts:
- They will not be the cheapest for a LONG time.
- They are not as efficient as most of the other current forms of energy production (in the short term).
- They don’t work in the dark…DUH!
However, the state of technology today has increased their viability immensly.
One of the main ingredients in making them more “efficient” is to produce them faster with the same energy input. Years ago, in the dark days of PV, it would take days if not weeks to produce a single panel large enough to produce usefull power output. These early panels were of silicon based semiconductors. Either you hook a bunch of small wafers together into a large frame or you tried to grow a large monolithic crystal of silicon.
Imagine a 2’ x 4’ frame with a herd of 4"-5" disks or squares inside of it. Leave room for the spacing needed to hook them together in series and you come up with about 60% of that 2’ x4’ panel actually producing power. Next you have to seal this whole mess in an environmentally comfy enclosure.
The company I work for produces a thin film semi-conductor PV on a sheet of standard 2’ x 4’ glass substrate. We can produce eight 2’ x 4’ substrates every two minutes. The coating is directly on the substrate and depending on how it is processed, various voltage/current configurations can be made. Sealing the film side of this substrate with either a cover glass or a conformal coating make it impervious to the elements. Of course there are downsides: baseballs, falling rocks, enormous bird droppings…etc. But as long as the panel doesn’t break, it will work when the sun comes up. If the sun doesn’t come up…a non-functioning solar panel will be the least of your worries.
The cheapest explanation of the solar philosophy is this:
If some of the electricity is from solar, less of the electricity is from other fuel sources. The less you burn today, the more you have for tomorrow.
I could go into the “save the planet” speech, but personally I’m kind of tired hearing myself. I do not profess to be a tree-hugger by any stretch of the imagination. Any of you who know me personally know this to be more than true. I eat meat in disturbing quantities and like it.
Converting your house over to solar electric is expensive. The panels themselves are usually the lowest cost component in the system. The killer is what is referred to as balance of systems.
PV panels output a DC voltage. The world runs on AC so you need an inverter to wiggle the voltage up and down. One could convert one’s entire house over to DC appliances, but that would add some cost also. Secondly, due to the unavoidable fact that solar energy requires mean old Mister Sun, you also would also need a bank of storage batteries if you wanted electricity at night.
Expanses of panels hooked to the grid would provide extra power during the power hungry air-conditioning days of summer.
My own philosophy: Every penny that those bastards at Edison don’t get from me is a personal victory against Evil.
By the way, those other leaders in PV research and production are big oil companies. Maybe they know something they aren’t telling us.
Or, just use solar when it’s available and use the regular power grid at night/during cloudy days/etc.
No batteries needed.
No, I was being generous.
BTW, I noticed the warranty on the system was for 20 years. You probably ought to get your break-even time down to the warranty time.
On the other hand, if you have a house or cottage a long way from the nearest power line, it’d be nice to have a system like this available.
If the energy is there, science will find a way to use it. It’s just a matter of time.
Remember, that all energy is either solar, geothermal/tidal or nuclear. Oil and gas are just stored-up solar energy.
According to a recent Scientific American article, we have use approximately one half the the Earth’s oil and gas reserves. Prices should start climbing dramtically within the next decade since we’ve extracted all the “easy” oil and have to look to more difficult sources. Once the price of oil rises sufficiently, serious R&D in solar energy and fusion power will become more cost-effective in relation.
Photovoltaic cells are not the only way to use solar energy. Biomass has been mentioned as an alternative. Clorophyll is more efficient than silicon, and even its low energy density is offset by the enormous area that low-maintenance plants can cover. Another reasonable solution is to put a big-ass mirror in the desert and heat up some water to drive a steam turbine. Again, not particularly efficient, but it should be relatively safe and you can’t argue with the fuel costs.
As our civilization expands, our energy needs will continue to increase. Conservation can perhaps eke out a few more years, but we aren’t getting any more oil; we will have to find ways to exploit alternative energy sources to preserve our level of civilization.
>> if you have a house or cottage a long way from the nearest power line, it’d be nice to have a system like this available.
Yup. that’s what they are used for but the cost of energy is not comparable to what you get from your friendly utility company.
A major factor also is that small home power systems require maintenance which is extremely expensive. The only way to get around this is with economies of scale: a huge solar farm. But then you still have the main problem that you are still not competitive and you have to add the cost of owning so much land. I remember seeing a study somewhere on the net that the energy produced by such an experimental farm hardly paid for the cost of owning the land.
Being technically inclined and a tinkerer myself, I often go into dreamy studies for installing some panels on my sailboat and in the end I always give up because it just is not justified in spite of how much I’d like to have it.
Sucellus I welcome your input a you obviously know what you are talking about. Living in DC I am tired of listening to people here who think wishful thinking makes things happen. Not only do they know squit about the facts, they are just not interested in learning about them because they may not support the conclusions they have already reached.
some links: http://www.homepower.com/ . . . . http://www.solarpv.com/
ZenBeam, I think your financial analysis falls far short as you do not account for any financial cost in the initial investment. Let me try to do something a bit more complete:
The true cost of the system, including subsidies is $16564 which amortized over 15 years at 9% means $168 / mo. Add another $32 / mo for maintenance and you get a cost of $200/mo.
For that you would be lucky if you got 1.4 x 6 x 30 Kwh/mo = 250 Kwh
Cost of Kwh = 80 cents
or more than ten times what it costs you to buy it from the power company (and this does not take into account the tylenols you’ll need when the system is giving you problems which would otherwise be the power company’s problems).
BTW, I just checked and here in DC I pay 5.267 cents / Kwh for the first 400 Kwh (I hardly ever exceed that). After that it goes up to 9 cents.
In any case I would have to be connected to the power grid as the solar system does not accumulate energy and would ot provide enough. Taking into account I have to be connected to the grid, my options are
A) Grid only. I get my energy cheap and with no capital investment on my part
B) Grid plus solar system: I invest $16000 of my money for the privilege of paying 15 times more for the energy that I generate than if I bought it from the power company.
Maybe some financial guru can convince me B is the way to go.
Oops, Phobos, I almost forgot about your question. You can find info about PV panels at http://www.solarpv.com/products_and_services.html
Regarding storage of electrical energy using batteries that’s another joke. Batteries are one of the most polluting items you can think of and their life is very limited.
I have calculated this for my boat. Manufacturers tell you a lead-acid battery can be cycled up to 500 times but I find this is stretching the truth and, in any case, batteries lose capacity over life. So, as a rule of thumb, I calculate a battery will give you over its lifetime the equivalent of 100 full discharges.
Let me do the math again then. A large 12 V marine deep cycle battery will sell for about $1 / Ah of nominal capacity. For that dollar I’ll get 100 Ah out of it over its lifetime which is about 1.15 Kwh.
In other words, even if the energy to recharge it is FREE (which it is in my case since electricity is included in my dock fee) every Kwh I use out of the battery costs me 87 cents.
Add to that the cost of generating the power and the inefficiency of the batteries (you have to put in about 40% more than you get out) and you get the picture.
In other words: cost of buying a Kwh at home from the power co: 5.6 cents
Cost of storing it in a battery for later use: 87 cents
I guess the vast right wing conspiracy is also preventing the development of better batteries, not only here but in the whole world. 
Is this also in the aformentioned article, or is this personal speculation?
True, once the economics drive it that way. But I think we are not looking 10 years down the road until we get to super-expensive oil ($100/bbl), but more like 30 years or more.
Biomass is fine, but do not underestimate the simply ENORMOUS amount of land area it takes to generate 1000 MW year-round.
According to Evan Hughes, Manager of Biomass Energy at the Electric Power Research Institute (who I met personally at a conference and talked to over dinner, so THAT is my cite):
-
it takes roughly 1000 acres of good agricultureal land per MW of actual harvest land at an energy density of 5 dry tons/acre/year. You also have to include another 5-20 or so acres of land per 1000 for process space. To replace 1000 Mw then takes, at a minimum, 1,005,000 acres of good agricultural land.
-
5 dry tons/acre is a realistic value for todays tech, but 13 dry tons/acre have been achieved in a laboratory setting. It is estimated that this must reach a density of 20 dry tons/acre in order to be cost-effective at today’s rates.
-
According to EPRI, at best biomass could only contribute from 10-25% of our current energy demand.
-
You cannot assume a 100% Greenhouse gas reduction, only about 93%. Still much better than 0% though.
-
Recent extended trials of large biomass co-fire burns include:
- TVA Allen Station (27 biomass MW, sawdust)
- TVA Colbert Station (3 biomass MW, sawdust)
- NYSEG Greenidge Station (11 biomass MW, wood)
- GPU Seward Station (3 biomass MW, sawdust)
- MG&E Blount St. Station (5 biomass MW, switchgrass)
- NIPSCO Michigan City Station (23 biomass MW, sawdust)
So you can see that interest continues, but only on a very small scale. I will say from my PERSONAL experience (as an expert in the field) that every single utility I have worked with in the last few years have been actively exploring ways to cofire biomass for economic, carbon reduction, and just purely environemtnal reasons (if you believe corporate Mission Statements).
Actually, you can argue with the cost and hassle. See the Solar 1 and Solar 2 projects for reference. There is a reason why they went nowhere…
I strongly disagree with the downplay on conservtion. One side task I do frequently is energy audits of residential areas, businesses, and so forth. The US has an incredibly wasteful society, and in many cases I find that energy demand can be slashed by up to 15% easily in residential areas with no decrease in the Standard of Living (SoL). In one very special case here in KC we found that 20% reductions were possible via demand-side management, with no SoL decrease. With a “moderate” (depending on your definition) SoL decrease this can be extended to be close to a 35-50% decrease in energy consumption. And think of the reduction in emissions as well!
I see demand-side issues as being much more cost-effective and practical now, rather than supply-side issues such as solar research.
I’ve had litle experience in solar power but I’m interested in any alternative power.My last experience was a solar panel I built. The panel was made exclusivly as a solar window being 4’x8’.I purchased a 4x8 sheet of foil backed polystyrene and painted the foil black.I then made a 4x8 wood frame from scrap wood.After assembling the thing I purchased a 100cubic ft per min fan from radio shack. I was able to raise the temperature of the air in my unheated basement in the winter from forty degrees to 50 degrees. I measured the temperature at the imput and at the output.I felt the experiment was a success.Unfortunately the house we live in now does not have south facing basement windows.
I currently use a solar powered elcctric fencer.The little PV charger is about 5"X7" and contains 16 cells. It does an excellent job of keeping a motorcycle battery charged.
The thing has been operating every day since march when I found it at a flea market.
Gee I guess it depends on what you expect from alternative power as to weather you are for or against it.
If you are naieve enough to expect miracles well I guess you can figure on disapointment.
Yep there are two other threads where we try deperately to stay on topic, however you are outdoing yourself in this one. I know from teaching power transfer theory some years ago that you could only hope to drive the lightest of loads (such as those you mentioned) with PV cells (but students came up with some very creative projects) but I never thought about it on a much grander scale such as commercial power. All of the cost/efficiency arguments made here are well taken, and I agree with the central point that we won’t see useable horsepower from solar until sience sees the need to make it so (natural resources begin to run out).
Perhaps this will involve some combination of increased efficiency of PV cells & some miracle breakthrough wherein power hungry loads become obsolete.
Oh damn. Somebody unplugged my perpetual motion machine. :mad:
Anthracite you are right (of course) about conservation and I would go further because quality of life is a very subjective concept. I use very little energy by using as little AC and heating as I can get by with. I do not see this as worse quality of living, just adapting to the seasons. I wear more clothes in winter, less in summer.
My 85 year old neighbor is on some government assistance program that pays for her utilities and she keeps the entire house like an oven in the winter. I can’t stand it in there for very long.
I go to homes where the overuse of the heating or AC is overwhelming to the point of making me feel uncomfortable. And look at people buying SUVs like crazy. Then instead of looking at ourselves, we blame corporate greed, the utility companies, the oil cartels etc. Anything but ourselves.
OTOH, I have to say something else about conservation in the long term: it won’t work unless we stabilise the population numbers. If each of us consumes half as much in resources and there’s three times as many of us, we’re still consuming 1.5 times as much. So the most efficient way to conserve energy is to avoid making more people who will need to use it.
barbitu8: “Solar energy may not be the answer, but what about geothermal energy?”
It’s being exploited. I’m only familiar with California but in that state there has been a geothermal plant for years near Calistoga and a newer plant near Calexico. There are even geothermal plants generating electricity in Indonesia, one of the worlds biggest oil producers. The problem is, there aren’t many suitable sites for geothermal energy production.
(Don’t tell Ukulele Ike but the geothermal plants in Indonesia were built by big, greedy, OIL companies.)
A question for Sailor: A lot of people in Mexico seem to have water tanks on the roofs of their house. I know that they put the tank there so that they have water pressure 24/7, not for hot water. However, it seems to me that in a tropical country or even subtropical country, this is a simple and cheap way to be able to take at least one warm shower every evening through much of the year. Yet most tropical countries I have visited do not have roof water tanks. Couldn’t a used 50 gallon drum painted black with a $4.50 valve from a toilet mounted on your roof and a connected with a few dollars worth of 3/4" pipe provide some savings on hot water from May to October even in DC?
Yes, solar heat and solar electricity are two very different animals.
I’ll say little about solar electricity. Solar heat, on the other hand…
IMHO the active solar heating system talked about in the sixties and seventies do seem to be a bit of a dead end in terms of upkeep and efficiency. But they were retrofitted onto existing structures, correct?
Some friends of mine built a house which was designed from the outset to capture and store heat. They literally do not need to fire up their wood stove at any time during the year, even in midwinter!
I slept in the unfinished house one February night when it was -28C outside, and the daytime temperature never rose above -15. Even with only partial insulation on the walls, and the fire in the wood stove out, the temperature inside the house never dropped below 6C! All I needed was a thick pile of blankets. 
Now, the house is close to finished: it has all its insulation, and a larger stove. My friends are working on interior finishes and other details.
How was this done? Extreme insulation in the roof (RSI8 or something/~R50). Thick (half-metre/1.5-foot) rammed-earth walls, with their insulation on the OUTSIDE, so that the walls can warm to room temperature and store heat in their mass. Huge windows on the equator-facing (in our area, south) side of the house, none on the polar-facing (north) side. Careful design of the shapes of the rooms and their arrangement, so that the low winter sun shines on the thick earth walls and heats them, while the high summer sun is shaded by the edge of the roof.
Indeed, during the summer, the house remains cool, because, with no sun shining on the interior walls, their temperature never rises to that of the external air. Hence, no need for mechanical cooling as well.
As a side effect, the design included garden-planters along the south wall under the windows. Now my friends can sit at their kitchen table, reach over, and pick fresh salad for dinner, while the snow falls… Me, I’m waiting for the orange tree to grow.
In this way, it’s quite possible to build a house capable of heating itself using only the sunlight that falls on it… but the house has to be specifically and thoroughly designed for it. My friends’ house is as purpose-built to heat and cool itself without additional mechanical aid, as a Porsche is built to go fast on roads. But it differs as much from a traditional North American stick-built house as the Porsche differs from a Model T.
It’s clear to me that because incoming solar heat is so diffuse, effective use of solar heat requires a far greater depth of design than simply adding another mechanical system to a previously-existing design.
This is not to say that traditional stick-built houses can’t be a lot more efficient than they sometimes are. My friends’ previous house was a prefab Viceroy, with big windows on the south and lots of insulation. They had heating bills of $50 a month or so in the winter, while their neighbours, who had a smaller house, had ten times and more the monthly heating bill!
My site about the house: http://www.sunspace.org. Now you know where my login name comes from…
Right now in my house:
-
There are 5 rooms with a total of 7 lights on, with no one in them. One is a ceiling fan/light combo, running at half speed.
-
There are 4 desktop PC’s, one laptop, one firewall - all running, while I use just one PC to post this.
-
The AC is set to the normal frigid “70”.
-
Ironically, there is a very small electric space heater on in the basement, to keep the cats from getting too cold.
-
A television is on, but no one is even on that floor.
-
A printer is on and idle, but will not be used for many days…
I’m wasting a lot of electricity here. I just don’t notice because:
- I’m preoccupied most of the time,
- MOST of it (the lights and TV) is the SO’s fault, and
- Thanks to very cheap electric power (the electric bill is normally about $130-150 or so) the cost is such a ridiculously small amount relative to our income that we don’t pay attention to it.
So, I am being very wasteful. And yes, I turned everything mentioned off (except the Cat Heater) before posting this.
Sunspace, yes, I agree that when things are designed to include things they are much better than retrofits. No question about that. I have read many books about energy efficient housing and like the idea. Unfortunately these houses are more suited to big lots and deep pockets. My old house was built some 75 years ago and any retrofits are expensive. When you get to a certain point, you are better of tering the house down and building a new one.
yeah, as I said I have solar panels and they really do not do that much but add this: In the winter water arrives barely above freezing temperature, sunlight is at a minimum and the yield of the solar panels is close to zero.
In the summer the water arrives easily at 80F = 27C and needs very little heating. The panels are collecting at their peak and the antifreeze solution overheats which is bad for it. The only way is to dump heat so I find myself doing things like using buckets of boiling water to flush the toilet.
To answer your question about having some storage on the roof, I do not think it would work. You need to have a greenhouse that lets in the light and keeps in the heat. If I just put a tank on the roof in the winter, the water will freeze. It will lose more heat by conductivity than it will gain by irradiation. Solar panels are built specifically for their purpose.
Note that in tropical countries the heating needs for water are minimal. In Cuba they had a little electric showerhead that heated the water as you showered but this is because the water is pretty warm to begin with. There’s no way you can do that in DC. (By the way, it looked so dangerous I didn’t dare turn it on).
I did some work in bottling plants for soft drinks in Mexico city. Now, in the carbonation process you need the beverage at very low temperature. In St Johns, Newfoundland, this was never a problem, but in Mexico city the refrigeration needs were fenomenal. Just this cost will make a difference between making the same product in Canada and in Mexico.
A machine can manufacture anywhere between 15K and 40k liters/hr. If you need to chill that flow by 25 - 28 C it gets expensive.
But getting back to roof tanks in Mexico, I do not believe they would provide any substantial heating. It could even be possible that heat losses at night would be greater than the heat gained during the day.
Anthricite
Surely you are kidding about the cats heater.
>> Surely you are kidding about the cats heater
I now have a new theory that all the energy crisis is the fault of people who own cats. We should put the cats on treadmills producing vast amounts of electric power, enough to power the entire continental US without having to worry about pollution etc.
No, I am not. The cats have all their beds downstairs, and it gets frigid with the A/C on. Since I am seriously decadent and energy wasteful, they have a little mini space heater to keep their beds warm and snuggly. This also helps in Winter too, otherwise they would have cold paws!
And, we found that the space heater greatly (actually, disproportionately IMO) lowers the relative humidity in the lower level, thus making the place much more wholesome and much less mildewy. In fact, it feels like every other part of the house.
(Sets her teeth, and waits for the “Cat Heater” mockery and flames to start pouring into this thread…)