Environmentally sustainable base load power

[cornbread_r2]

Some think that liquid metal batteries or something similar can help smooth the intermittent power-producing problems inherent with wind and solar.

 

[Loren Pechtel]

Some think that liquid metal batteries or something similar can help smooth the intermittent power-producing problems inherent with wind and solar.

There's a lot more hype about new battery technology than viable new batteries. I'll take a wait and see approach.

 

[Togo]

EV 13 means 1/4 of the light--and thus a quarter of the power.

That doesn't follow. What level of illumination is the most efficient for the array you're considering, and how strong is the tail-off after that point?

 

[Loren Pechtel]

EV 13 means 1/4 of the light--and thus a quarter of the power.

That doesn't follow. What level of illumination is the most efficient for the array you're considering, and how strong is the tail-off after that point?

If the array doesn't peak at near full sunlight you're going to lose even more power that way.

 

[Togo]

That doesn't follow. What level of illumination is the most efficient for the array you're considering, and how strong is the tail-off after that point?

If the array doesn't peak at near full sunlight you're going to lose even more power that way.

No, the efficient way would be to peak at modal conditions. There's still nothing to suggest that power generated has a linear relationship with light intensity, unless you have a source? It would follow if the efficiency of conversion were near 100%, but that's nowhere near true.

 

[Loren Pechtel]

If the array doesn't peak at near full sunlight you're going to lose even more power that way.

No, the efficient way would be to peak at modal conditions. There's still nothing to suggest that power generated has a linear relationship with light intensity, unless you have a source? It would follow if the efficiency of conversion were near 100%, but that's nowhere near true.

It's slightly worse than linear:

http://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-light-intensity


Simply deciding that reality is how you would like it to be doesn't work very well.

 

[Togo]

No, the efficient way would be to peak at modal conditions. There's still nothing to suggest that power generated has a linear relationship with light intensity, unless you have a source? It would follow if the efficiency of conversion were near 100%, but that's nowhere near true.

It's slightly worse than linear:

http://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-light-intensity

Um, thanks for the link, but you've given me an article on light intensities above that of provided by sun, and a graph showing how the relationship between resistance and voltage varies with intensity. I can't where it actually supports what you said.

This might be an interesting article, since it discusses how solar arrays can be networked, and what kind of power output you get from them in cloudy conditions:

http://geomodelsolar.eu/_docs/paper...ct-on-PV-power-production-in-South-Africa.pdf

 

[skepticalbip]

http://www.streetdirectory.com/travel_guide/125965/computers/effects_of_clouds_on_a_solar_panel.html

It's slightly worse than linear:

http://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-light-intensity

Um, thanks for the link, but you've given me an article on light intensities above that of provided by sun, and a graph showing how the relationship between resistance and voltage varies with intensity. I can't where it actually supports what you said.

Is this closer to what you were looking for?

http://www.streetdirectory.com/travel_guide/125965/computers/effects_of_clouds_on_a_solar_panel.html
Will Clouds Affect My Solar Panels?

Clouds do affect solar panels. The amount of power your solar panels can produce is directly dependent on the level of light they receive.

In full, bright sunlight, solar panels receive maximum levels of light. During those "peak" sunlight hours, your solar panels will produce power at their maximum capacity.

When clouds cover the sun, light levels are reduced. This does not shut down power production, however. If there is enough light to cast a shadow, in spite of the clouds, your solar panels should operate at about half of their full capacity. Thicker cloud cover will reduce operations further. Eventually, with heavy cloud cover, solar panels will produce very little useful power.

Solar power density is about 1.4 KW/square meter under full sun at the Earth's surface. Solar panel effeciency is about 15% so can produce about 210 watts/ square meter under those conditions. However on light cloudy days when shadows can be seen the power output is reduced to about half or 105 watts. More cloudy days will reduce the output even more.

 

[steve_bnk]

Photo detectors are characterized by quantum efficiency. A current or voltage per photon.

Absorption occurs when the energy of the photon matches the band gap voltage of the material.

It is 'quantum mechanical'. As a mechanical analogy when the frequency of the photon matches the resonant frequency of the atom/system absorption occurs.

Photo resistors are characterized as change in resistance per photons.

To be pedantic D-Star is the unit of measurement. Note that irradiance, radiance, and intensity have meanings that may differ by discipline.

http://en.wikipedia.org/wiki/Specific_detectivity

Radiant intensity is defined in terms of a solid angle. To a small solar panel the looks like a distant point source radiating into a solid angle.

http://en.wikipedia.org/wiki/Radiant_intensity

'...In radiometry, radiant intensity is a measure of the intensity of electromagnetic radiation. It is defined as power per unit solid angle. The SI unit of radiant intensity is watts per steradian (W·sr⁻¹). Radiant intensity is distinct from irradiance and radiant exitance, which are often called intensity in branches of physics other than radiometry. In RF engineering, radiant intensity is sometimes called radiation intensity..'

http://en.wikipedia.org/wiki/Intensity_(physics)

'...In physics, intensity is the power transferred per unit area. In the SI system, it has units watts per metre squared (W/m²)...'

http://en.wikipedia.org/wiki/Irradiance

'...Irradiance is the power of electromagnetic radiation per unit area (radiative flux) incident on a surface. Radiant emittance or radiant exitance is the power per unit area radiated by a surface. The SI units for all of these quantities are watts per square meter (W/m²), while the cgs units are ergs per square centimeter per second (erg·cm⁻²·s⁻¹, often used in astronomy). These quantities are sometimes called intensity, but this usage leads to confusion with radiant intensity, which has different units.
All of these quantities characterize the total amount of radiation present, at all frequencies. It is also common to consider each frequency in the spectrum separately. When this is done for radiation incident on a surface, it is called spectral irradiance, and has SI units W/m³, or commonly W·m⁻²·nm⁻¹.
If a point source radiates light uniformly in all directions through a non-absorptive medium, then the irradiance decreases in proportion to the square of the distance from the object...'

The term in the data sheet is irradiance, the term I am used to in radiometry.

Datasheet for a solar cell. See graphs at bottom page 2. Quantum efficiency and spectral response.

http://ixapps.ixys.com/DataSheet/SLMD121H09.pdf

'...Relative Lighting Power Density

The figure above compares relative power density for various lighting conditions in units of Watts per square meter (W/m^2).

The reference standard condition is 1 Sun and is equal to 1000 Watts
per square meter of sunlight irradiance at a constant 25°C cell temperature and at 1.5 Air Mass(Air Mass stands for a well defined light spectrum which appears if the sunlight goes through the earth’s atmosphere at a defined angle)....'

 

[steve_bnk]

Factor in power conversion efficiencies and be pessimistic on top of that. Say 50 w/m^2 out in the desert ona clear day and Sun overhead.


1 mega watt/50 watts = 1e6/50 = 20000m^2/mega watt.


That is a rectangle 142x142 meters.


Major existing solar voltaic utilities.Israel is going solar in a big way.


http://en.wikipedia.org/wiki/List_of_photovoltaic_power_stations


I can't find the link. A southwest utility built a station using off the shelf panels and distributed off the shelf small DC to AC inverters. Standard electrical catalogswitchgear.


I have a major problem when I hear Obama say we need R&D and innovation in energy. It has all beendone. All's we have to is implement.


Coal has a powerful lobby.


Several utilities have a hold on new private home systems connecting to a local grid and selling energy tothe utility. It can affect rate structures, and it may affect maintaining 3 phase load balance at the transformers.




http://money.msn.com/saving-money-tips/post--utilities-launch-campaign-against-home-based-solar


'...It's all about net metering


The campaign centers on a practicecalled net metering. Laws in many states let solar homes send excesselectricity back to the utility. Those homeowners are compensatedwith credit on their bills.


Carrie Hitt, an official with the SolarEnergy Industries Association, an industry group, told Money TalksNews that 46 states have some form of net metering.


Some states, like Kansas, requireutility companies to get a share of their power from renewablesources.


The utilities claim net metering dumpsunfair costs on customers who don't have solar panels. It leavesfewer households covering the costs of keeping utility systemsrunning, they say...'


Politics is preventing us from headingtowards energy independence.

 

[steve_bnk]

nm

 

[bilby]

Storage concerns aside, solar power is still too expensive.

Right now, I can buy a 4.5kW rated system from Origin Energy, that costs $6,765, fully installed. That system, according to the Clean Energy Council, will in a good 45m² unshaded site in Brisbane, facing North or North-West, generate an average 6,899kWh per year, based on typical weather conditions.

Electricity here is expensive, and I pay 26.73c/kWh for it; so my potential savings are 6,899kWh x $0.2673/kWh = $1,639 per annum, or on average, $136.59 per month. That means it would take over four years for the system to have paid for itself, even discounting the cost of the upfront capital expenditure, and any maintenance, repair or depreciation. I have moved house three times in the last four years; had I installed a solar power system in each place, I would be about $13,000 out of pocket.

Assuming (and it is a big assumption) that I can settle here and never move again, I could buy a system today.

If I borrowed against my home at my bank's current home mortgage rate, I will pay 5.23% APR for the $6,765 additional loan. At those rates, it will take four years and eight months before I have saved enough in power bills to pay off the loan plus interest, and am making any return at all on my investment - assuming I don't move house, and that the inverter and panels run at the projected output rate consistently for all that time without maintenance, repair or replacement.

I am simply not prepared to gamble nearly $7,000 on the probability that nothing will go wrong - particularly not a change in circumstances requiring me to move house, and donate my solar power system to the next buyer - in the best part of five years.

If electricity was to rise to nearer 60c/kWh, then it would be a 2 year ROI, which would be a bet I would be prepared to take; or if power prices remained stable, but the installed cost of a 4.5kW unit came down to about $3,100 (also giving a 2 year ROI).

In summary, domestic solar power is about twice as expensive as I am prepared to pay at present. I hope the cost will continue to fall; when the falling cost and/or rising power price makes a 2 year ROI possible, then I will take the plunge.

Until then, I would prefer to buy nuclear power (at any retail price below 60c/kWh) rather than coal power at roughly the same price*.




*Nuclear and coal are roughly the same price - according to the OpenEI figures on Wikipedia, Coal costs between 40 and 80USD/MWh, while nuclear costs around 60USD/MWh. PV Solar costs around 280USD/MWh, while onshore wind - the least expensive of the non-nuclear renewables - is comparable in cost to nuclear and coal (but of course, has the problem of long periods of calm weather to overcome).

 

[Togo]

Storage concerns aside, solar power is still too expensive.

Right now, I can buy a 4.5kW rated system from Origin Energy, that costs $6,765, fully installed. That system, according to the Clean Energy Council, will in a good 45m² unshaded site in Brisbane, facing North or North-West, generate an average 6,899kWh per year, based on typical weather conditions.

Electricity here is expensive, and I pay 26.73c/kWh for it; so my potential savings are 6,899kWh x $0.2673/kWh = $1,639 per annum, or on average, $136.59 per month. That means it would take over four years for the system to have paid for itself, even discounting the cost of the upfront capital expenditure, and any maintenance, repair or depreciation.

Do you really pay the same rate day or night? Most places daytime electricity is more expensive, and night cheaper, but if you're in an area where the main consumption is air conditioning, maybe that doesn't hold true.

It's also worth pointing out that electricity generated above your consumption doesn't get you nearly as much - the prices selling back to the grid are much lower than the cost savings of not taking from the grid in the first place, so power generated doesn't always translate into a cost saving. A storage heater might help.

Assuming (and it is a big assumption) that I can settle here and never move again, I could buy a system today....

...In summary, domestic solar power is about twice as expensive as I am prepared to pay at present. I hope the cost will continue to fall; when the falling cost and/or rising power price makes a 2 year ROI possible, then I will take the plunge.

The problem doesn't seem to be the cost though, but rather that you move too often to want to spend money on your property. I was in the same boat in my last place - since I intended to move there wasn't any point in improving it. By the same logic I also didn't replace the kitchen ceiling (water damage), retile the bathroom, or paint it, inside or out. That's not really because of the price of paint though.

By contrast, my in-laws have bought solar panels precisely because they're retiring, and they can spend their pension money on it. Given that annuity rates are pretty awful at the moment, reducing fuel bills in the future makes more sense.

Until then, I would prefer to buy nuclear power (at any retail price below 60c/kWh) rather than coal power at roughly the same price*.

Certainly, if you're planning on moving, buying electricity from a power plant makes more sense that installing your own generation system. But that's nothing to do with solar versus nuclear. If you were sitting outside a huge solar facility, and someone was offering home fusion plants for $7000, you'd have exactly the same problem.

 

[bilby]

Do you really pay the same rate day or night? Most places daytime electricity is more expensive, and night cheaper, but if you're in an area where the main consumption is air conditioning, maybe that doesn't hold true.

I pay a lower rate at night; but any savings from solar will come off the peak rate consumption at the rate quoted. Obviously solar would be an even worse prospect if some of the savings were at the lower rate - but that is unlikely to be the case unless there is a major shift to solar that pushes the daytime cost down.

It's also worth pointing out that electricity generated above your consumption doesn't get you nearly as much - the prices selling back to the grid are much lower than the cost savings of not taking from the grid in the first place, so power generated doesn't always translate into a cost saving. A storage heater might help.

heating is unnecessary in this climate except in the coldest days of winter. I use a 2kW fan heater, perhaps for an hour in the morning, for maybe four or five weeks a year - maybe 70kWh/year in total for heating. Most of my power is used for cooling and refrigeration, which are big energy drains in this climate.

Assuming (and it is a big assumption) that I can settle here and never move again, I could buy a system today....

...In summary, domestic solar power is about twice as expensive as I am prepared to pay at present. I hope the cost will continue to fall; when the falling cost and/or rising power price makes a 2 year ROI possible, then I will take the plunge.

The problem doesn't seem to be the cost though, but rather that you move too often to want to spend money on your property.

It is both. A four to five year ROI is just not good enough - I can get the same return, without the risk of a blown inverter costing me thousands, from other investments - or simply by paying more off my home loan. The savings are enough to pay for the electricity I don't generate from sunlight; so economically, it makes little sense - at current prices.

I was in the same boat in my last place - since I intended to move there wasn't any point in improving it. By the same logic I also didn't replace the kitchen ceiling (water damage), retile the bathroom, or paint it, inside or out. That's not really because of the price of paint though.

By contrast, my in-laws have bought solar panels precisely because they're retiring, and they can spend their pension money on it. Given that annuity rates are pretty awful at the moment, reducing fuel bills in the future makes more sense.

It certainly makes sense if the hardware is subsidised to bring costs down; or if power is expensive; or if there is a generous 'feed-in bonus' - ie you are paid more for power you put into the grid than you pay for power you take out. None of those things are true here.

Until then, I would prefer to buy nuclear power (at any retail price below 60c/kWh) rather than coal power at roughly the same price*.

Certainly, if you're planning on moving, buying electricity from a power plant makes more sense that installing your own generation system. But that's nothing to do with solar versus nuclear. If you were sitting outside a huge solar facility, and someone was offering home fusion plants for $7000, you'd have exactly the same problem.

Indeed. But right now I am not planning to move for many years. I have only raised this as a matter of risk - two equal returning investments are not equal if one is inherently more risky than the other.

I am in the process of putting in a new kitchen here that cost more than the 4.5kW solar array mentioned above; I can justify the new kitchen in terms of its utility compared to its cost - but solar costs about twice what it needs to (or electricity costs about a third of what it needs to) to justify the outlay.

I fully intend to keep an eye on the prices and to go solar once it is viable to do so. Solar is getting cheaper all the time; and electricity prices keep rising, so it might well be viable in a few years. It isn't today though - and I am in a great location for solar. It really only works today for people with access to subsidies that are not available in my location.

 

[Loren Pechtel]

It's slightly worse than linear:

http://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-light-intensity

Um, thanks for the link, but you've given me an article on light intensities above that of provided by sun, and a graph showing how the relationship between resistance and voltage varies with intensity. I can't where it actually supports what you said.

Yeah, the text only refers to above 1 sun--but note the calculator on the page. That goes both up and down.

This might be an interesting article, since it discusses how solar arrays can be networked, and what kind of power output you get from them in cloudy conditions:

http://geomodelsolar.eu/_docs/paper...ct-on-PV-power-production-in-South-Africa.pdf

Note that even your link says heavy cloud means very little power production. Note, also, that most of South Africa is a pretty dry place, you're not going to get a lot of time when big areas are covered in clouds.

 

[Loren Pechtel]

Is this closer to what you were looking for?

http://www.streetdirectory.com/travel_guide/125965/computers/effects_of_clouds_on_a_solar_panel.html
Will Clouds Affect My Solar Panels?

Clouds do affect solar panels. The amount of power your solar panels can produce is directly dependent on the level of light they receive.

In full, bright sunlight, solar panels receive maximum levels of light. During those "peak" sunlight hours, your solar panels will produce power at their maximum capacity.

When clouds cover the sun, light levels are reduced. This does not shut down power production, however. If there is enough light to cast a shadow, in spite of the clouds, your solar panels should operate at about half of their full capacity. Thicker cloud cover will reduce operations further. Eventually, with heavy cloud cover, solar panels will produce very little useful power.

Solar power density is about 1.4 KW/square meter under full sun at the Earth's surface. Solar panel effeciency is about 15% so can produce about 210 watts/ square meter under those conditions. However on light cloudy days when shadows can be seen the power output is reduced to about half or 105 watts. More cloudy days will reduce the output even more.

Sure of that 1.4 kw/m^2??? I think that's the energy density in space, not on the ground.

And if there's enough light to cast shadows the clouds are pretty thin.

 

[Loren Pechtel]

Storage concerns aside, solar power is still too expensive.

Right now, I can buy a 4.5kW rated system from Origin Energy, that costs $6,765, fully installed. That system, according to the Clean Energy Council, will in a good 45m² unshaded site in Brisbane, facing North or North-West, generate an average 6,899kWh per year, based on typical weather conditions.

Electricity here is expensive, and I pay 26.73c/kWh for it; so my potential savings are 6,899kWh x $0.2673/kWh = $1,639 per annum, or on average, $136.59 per month. That means it would take over four years for the system to have paid for itself, even discounting the cost of the upfront capital expenditure, and any maintenance, repair or depreciation. I have moved house three times in the last four years; had I installed a solar power system in each place, I would be about $13,000 out of pocket.

Given those economics I would jump at it--why do you think the new owner wouldn't pay anything additional for the house with the solar installation??

(Or are you in a rental? Capital improvements in a rental never make sense.)

 

[bilby]

Storage concerns aside, solar power is still too expensive.

Right now, I can buy a 4.5kW rated system from Origin Energy, that costs $6,765, fully installed. That system, according to the Clean Energy Council, will in a good 45m² unshaded site in Brisbane, facing North or North-West, generate an average 6,899kWh per year, based on typical weather conditions.

Electricity here is expensive, and I pay 26.73c/kWh for it; so my potential savings are 6,899kWh x $0.2673/kWh = $1,639 per annum, or on average, $136.59 per month. That means it would take over four years for the system to have paid for itself, even discounting the cost of the upfront capital expenditure, and any maintenance, repair or depreciation. I have moved house three times in the last four years; had I installed a solar power system in each place, I would be about $13,000 out of pocket.

Given those economics I would jump at it--why do you think the new owner wouldn't pay anything additional for the house with the solar installation??

(Or are you in a rental? Capital improvements in a rental never make sense.)

There doesn't appear to be any significant increase in the prices paid for houses with or without solar power systems around here. I don't know why that is, but market irrationality is not unusual, so there may not be any good reason at all. On the other hand, one rational reason may well be the same reason why I didn't buy a place with solar already installed, despite not having to pay for it if I did - there are other more important factors - location, layout, structural soundness, etc. that outweigh the simple existence of a solar power system.

Capital improvements in a rental here would almost certainly be unlawful; and certainly stupid. Rentals here are typically based on short leases - 6 months is typical, a year is rare, more than that almost unheard of - and no alterations to the property are allowed without landlord approval. No sane person would buy his landlord a $7,000 gift, unless they had a much more direct relationship than merely landlord and tenant.

Lots of people around here are going solar; but IMO it isn't yet a good enough deal. It is rather like buying a computer (and indeed, Moore's Law seems to apply to solar panels as well as to processors); Why buy today, when in a couple of years the same money will get you something far better - or the same system will cost far less?

Ultimately the maximum ROI a person will accept is a personal decision. I take a conservative view, and want a 2-3 year ROI. 4-5 years is too much IMO. YMMV.

One additional factor - at the moment, as I said, a lot of people are going solar in my area. This is largely due to 'hard sell' tactics which I am loathe to encourage - door to door solar sales are a pestilence in this suburb right now. It also means that there are many 'fly by night' operators doing shoddy installs and/or using sub-standard parts. I would rather be a late adopter, after the most of the shonky dealers have moved on because the more gullible customers have all been sold half-baked systems, and the remaining potential customers are too discerning for their shady business model.

 

[Togo]

Um, thanks for the link, but you've given me an article on light intensities above that of provided by sun, and a graph showing how the relationship between resistance and voltage varies with intensity. I can't where it actually supports what you said.

Yeah, the text only refers to above 1 sun--but note the calculator on the page. That goes both up and down.

And shows me how the relationship between resistance and voltage varies with intensity. Again, I'm not sure how that supports what you said.

This might be an interesting article, since it discusses how solar arrays can be networked, and what kind of power output you get from them in cloudy conditions:

http://geomodelsolar.eu/_docs/paper...ct-on-PV-power-production-in-South-Africa.pdf

Note that even your link says heavy cloud means very little power production.

Indeed so. But not zero, and certainly not zero all day everywhere.

Note, also, that most of South Africa is a pretty dry place, you're not going to get a lot of time when big areas are covered in clouds.

??? So is most of Australia.

One additional factor - at the moment, as I said, a lot of people are going solar in my area.

A large capital investment is never going to appeal to everyone. If it's appealing to lots of people, that's probably enough, isn't it?

Around my way (London) the RoI is more like seven years, but there's also a problem with planning regulations. The lady who put solar panels on the side of her house got complaints from the neighbours - she lives in a conservation area where they take the appearance of the house very seriously. If you're putting black solar panels on a black tile house facing the correct direction, then fine, but most roofs aren't that well aligned.

 

[bilby]

Yeah, the text only refers to above 1 sun--but note the calculator on the page. That goes both up and down.

And shows me how the relationship between resistance and voltage varies with intensity. Again, I'm not sure how that supports what you said.

This might be an interesting article, since it discusses how solar arrays can be networked, and what kind of power output you get from them in cloudy conditions:

http://geomodelsolar.eu/_docs/paper...ct-on-PV-power-production-in-South-Africa.pdf

Note that even your link says heavy cloud means very little power production.

Indeed so. But not zero, and certainly not zero all day everywhere.

Note, also, that most of South Africa is a pretty dry place, you're not going to get a lot of time when big areas are covered in clouds.

??? So is most of Australia.

One additional factor - at the moment, as I said, a lot of people are going solar in my area.

A large capital investment is never going to appeal to everyone. If it's appealing to lots of people, that's probably enough, isn't it?

Around my way (London) the RoI is more like seven years, but there's also a problem with planning regulations. The lady who put solar panels on the side of her house got complaints from the neighbours - she lives in a conservation area where they take the appearance of the house very seriously. If you're putting black solar panels on a black tile house facing the correct direction, then fine, but most roofs aren't that well aligned.

Roofs here are usually white or silver (and are more often corrugated steel than any other material). A house with a black or dark roof would be unbearably hot. Light coloured tiles are more common in newer homes; and the worst McMansions have dark tiles that presumably look good to architects in Melbourne or Sydney, but are really not right for the Queensland climate.

That does make discrete solar installations a touch tricky. But it is not a big factor here, we don't have huge numbers of heritage listed homes, except in the middle of the major cities - and even there, much of the old stuff has long since gone.

Our oldest buildings are barely 200 years old.

Most places also have loft insulation to keep the heat out - the loft space can easily be 50^oC, and you don't want to have a ceiling at that temperature, so good insulation is a must - and a roof vent to let the hot air out.