Is now a good time to invest in solar?

[OmCheeto]

Back to the question? Do I need a pump?

Yes.

I did an experiment last summer using 1/2 inch 100' long black irrigation hose and a $22 http://www.cabelas.com/link-12/product/0001519012155a.shtml?cmCat=perf&rid=0987654321&cm_mmc=Performics-_-CSE-_-GoogleBaseUSA-_-0001519012155a&mr:trackingCode=DB6184C8-958E-DF11-A0C8-002219318F67&mr:referralID=NA". The system collected ~2.3 kwh of thermal energy in about 3.5 hours.

With no pump, you are just going to heat the water in the hose.

Some numbers:
flow: 1.6 gpm (~ 24 watts pump)
area of hose: 0.27 m^2
system fluid capacity: 32 gallons
max delta T / hr: 11 'F
To = 61.7'F
Tf = 90.9'F

Eek! Late for work. BBL.

 

[OmCheeto]

...to be connected to a radiator in the basement. ...

It sports about 100' of black hose in the collector...

You also have to remember that if the system is unpressurized, the weight of the water will draw a vacuum on your black hose. It had better be a robust hose, otherwise it will collapse.

(been there, done that. Black garden hose on the roof to the rubbermaid at ground level experiment. FAIL! Hose collapsed.)

 

[mugaliens]

I'm thinking MHD is the only solution

The only method of natural flow of the water would be through natural convection, and for that to work the heat source has to be below the radiator.

(slaps forhead) For some reason I was forgetting the fact the collector is about 4' above the radiator. You're right, of course. A pump is definitely required. This brings to mind some sort of passive system, though, much like a hammer pump... heh-heh... Perhaps a waterfall pump?

Just get a small pump, they aren't THAT expensive...

I've checked with Home Depot and Lowes, but aside from sump (bilge) pumps, all I get from them are blank stares, so I went to two pool places, but their pumps are way too big and designed to be used in pump houses (they leak). I need a small, non-leaking pump.

Does anyone have any links to pumps between 0.1 gpm to 5 gpm with which they've worked, are cheap, and are long-term reliable?

Eek! Late for work. BBL.

Lol - thanks for the numbers! Between your factors on kW-hr, time, and area, I can calculate some better estimates for here, but I'd need to know some measure of your area's solar influx on a median basis, either annual, seasonal, or monthly basis (I don't need to know your area).

You also have to remember that if the system is unpressurized, the weight of the water will draw a vacuum on your black hose. It had better be a robust hose, otherwise it will collapse.

(been there, done that. Black garden hose on the roof to the rubbermaid at ground level experiment. FAIL! Hose collapsed.)

Only about 4' to 6' of head. Shouldn't collapse a heavy-duty rubber garden hose (which I'm using for the collector). Besides, most of these systems are pressurized. I won't need much. The gas/water/radiator system in my home in Germany was pressurized at about 35 psi, but the green range was something like 20 to 45 psi. The landlord said "keep it around 30." I'd increase system pressure by means of the attached faucet to 35 psi, then check it once a month. About once every eight months I'd use the faucet, and walla!

Question is - where'd missing water go?? ! I never saw any leaks... Perhaps several micro-leaks which simply evaporated before they became puddles?

Anyway, this very modern and very efficient system did have its pump in the closet, along with a drain. I never saw a drop of water which might go down the drain, but that re-raises the question of microleaks. Who's a plumbing expert, here? Are microleaks (those which leak, but evaporate before they drip or puddle) common? I know such leaks can be avoided altogether in plumbing via well-executed materials and construction techniques. I also know of certain leak-sump systems which are effectively closed, but they're not cheap. Other, more exotic systems involving ferrofluids make effective zero-breach seals, but only up to http://en.wikipedia.org/wiki/Ferrofluidic_seals" .

Is there any way I can seal this system in toto, without resorting to such exotic measures? Perhaps by enclosing the pump in a pressurized environment equaling that of the fluid pressure? Symbiotic stacks* would do, but may lead to the encroachment of fluid on the pump body, and pose serious cooling issues with most pumps, which are air-cooled.

Pump supply system pressure itself is used to provide fluid to a a simple pipe column (or same-head air pressure vessel) which maintains pump housing pressure, thereby equaling the exit pressure at the bearings. Still - how does one continue to air-cool the pump? I'm thinking one might need a second system, a cooling system for the pump housing, but then... How does one seal that?

 

[OmCheeto]

(slaps forhead) For some reason I was forgetting the fact the collector is about 4' above the radiator. You're right, of course. A pump is definitely required. This brings to mind some sort of passive system, though, much like a hammer pump... heh-heh... Perhaps a waterfall pump?



I've checked with Home Depot and Lowes, but aside from sump (bilge) pumps, all I get from them are blank stares, so I went to two pool places, but their pumps are way too big and designed to be used in pump houses (they leak). I need a small, non-leaking pump.

Does anyone have any links to pumps between 0.1 gpm to 5 gpm with which they've worked, are cheap, and are long-term reliable?



Lol - thanks for the numbers! Between your factors on kW-hr, time, and area, I can calculate some better estimates for here, but I'd need to know some measure of your area's solar influx on a median basis, either annual, seasonal, or monthly basis (I don't need to know your area).

Insolation, kWh/m²/day 1.15 1.99 3.01 4.05 4.89 5.27 5.59 5.08 3.92 2.34 1.34 1.01
January through December

Only about 4' to 6' of head. Shouldn't collapse a heavy-duty rubber garden hose (which I'm using for the collector). Besides, most of these systems are pressurized.

I've changed my mind about your hose collapsing.
My prototype had the pump at ground level.
If your system is open to atmosphere above the level of the collector hose, then it shouldn't collapse. And I can think of no good reason why your system should be pressurized, other than by the head provided by your expansion tank. And that's where I'd put my pump.

I would answer your other questions, but I'm late for work again.

 

[mheslep]

Insolation, kWh/m²/day 1.15 1.99 3.01 4.05 4.89 5.27 5.59 5.08 3.92 2.34 1.34 1.01
January through December

In NJ? Tilted to latitude or flat? There's a difference in result.

 

[OmCheeto]

In NJ? Tilted to latitude or flat? There's a difference in result.

Jersey? I'm an Orygoonian. You've obviously mixed me up with Artman.

And what the hell is MHD?

 

[Astronuc]

Solar Power Projects Face Potential Hurdles
http://www.nytimes.com/2010/10/29/business/energy-environment/29solar.html

BrightSource Energy has a $2 billion project in the Mojave desert in S. California. The project, Ivanpah, is the first large-scale solar thermal power plant to be built in the United States in two decades. Apparently this is one of nine projects planned for California and Arizona. However, they seem to need substantial financial support from the federal government in the form of loan guarantees, tax credits and/or subsidies.

And even then the economics is still questionable.

The competitiveness of large-scale solar thermal plants in California also depends on the cost of natural gas, the state’s dominant source of electricity. According to Mr. Bullard, gas-fueled plants can produce electricity for about 10 cents a kilowatt-hour. After including the government subsidies, solar thermal plants are expected to generate power at 13 to 17 cents a kilowatt-hour, which the industry says is close enough in price to be competitive.

. . . .
Tessera Solar, based in Houston, has received federal approval to build two solar power plants that together would generate nearly 1,400 megawatts from 54,900 large solar dishes installed on 10,000 acres of government land. The company is seeking loan guarantees to help finance more than $4.6 billion in construction costs.

. . . .

 

[mheslep]

Solar Power Projects Face Potential Hurdles
http://www.nytimes.com/2010/10/29/business/energy-environment/29solar.html

BrightSource Energy has a $2 billion project in the Mojave desert in S. California. The project, Ivanpah, is the first large-scale solar thermal power plant to be built in the United States in two decades. Apparently this is one of nine projects planned for California and Arizona. However, they seem to need substantial financial support from the federal government in the form of loan guarantees, tax credits and/or subsidies.

And even then the economics is still questionable.

I find it difficult to ever cut the government involvement away from energy projects, so that one can see at last the thing just for what it is. Yes the solar projects get subsidies, but then a major recurring cost for solar plants is property taxes - the government giveth and the government taketh away. Property taxes are less out the middle of nowhere, but that then requires expensive transmission, once again requiring negotiation with every town, country, and state government the lines pass through.

 

[knickick]

Hi Artman. I think this will help you in your question http://www.sunpowerport.com.

 

[Artman]

Time for another report. With Winter fast approaching and the days getting shorter, I've noticed a definite decline in energy production from the system. On what we would call a "Screaming Sunny Day" which is a cloudless, haze-less day our production is only about 30 (down almost 20 from Spring and Summer). It still peaks at a decent level during the height of the day about 7.5 kW to 8.0 kW out of 8.8 kW design.

The system has produced overall 10.582 MWh for around 11 months of operation (Started mid Jan) and the design was for 11.000 MWh per year. So, with 1 month still to go, I think we will finish above design levels.

SREC sales have been good at around $600 as well.

One of the big benefits that I have noticed is that we could live more comfortably without it costing us more money for energy. We ran our AC on days that were a bit too humid for comfort in the Summer where we would have maybe just used fans before, and we've been using electric space heaters now to supplement the fossil fuel heat. Our meter is still about 750 kWh below 0.

 

[mheslep]

Small digression: I wonder if the EV/PHEV makers will eventually accommodate direct DC battery charging given the proliferation of residential solar panels. Avoiding the DC/AC inversion improves efficiency, and certainly reduces capital cost if the the panels were dedicated to only DC loads so that no inverted is required.

 

[Fish4Fun]

Small digression: I wonder if the EV/PHEV makers will eventually accommodate direct DC battery charging given the proliferation of residential solar panels. Avoiding the DC/AC inversion improves efficiency, and certainly reduces capital cost if the the panels were dedicated to only DC loads so that no inverted is required.

Really it has more to do with the Solar installation & the car. If there were a "standard" battery voltage (12V, 24V, 36V, ... , 275V, 375V) then the task might be simply a matter of matching your grid tied inverter input voltage to your car's charging voltage, but you would still require a "charge controller" to regulate the current into your car's batteries, and really, an AC to DC charger is not much more or less efficient than a DC to DC charge controller.

Artman,

I find your story and this thread fascinating. I have been researching Renewable Energy for quite some time, but have never been able to make Solar PV work on paper. The Federal Tax Credit of 30% combined with my State's (NC) $10,500 Tax Credit Maximum are not quite as attractive as NJ's SRECs. NC has started a 10% Renewable Energy Tax paid by all consumers of Grid Power, and created mandates for the percentage of grid power that has to come from renewable sources, but there are as of yet, no real incentives to consumers other than what local POCOs might offer. Net Metering is available only if the POCO decides to offer it, and the State treats renewable energy savings as income! By law, only 20% of any Renewable Energy Improvements are added to the property tax assessment; however, the property tax assessment process is so subjective in my area that the State law is meaningless.

The POCO in my immediate area will grudgingly allow you to sell excess power back to the grid only @ wholesale. Wholesale prices are to be determined by them, but the excess cannot exceed your monthly bill. You of course have to pay for all of the equipment/inspections/permits etc, and there is a monthly maintenance fee for having the equipment you purchased connected to their lines.

So, for ME the "Time is Not right" for solar PV. Essentially left to stand on it's own merits, as it is here in NC, the "break even point" is ridiculous. Assuming I installed a 20kW PV array, and could average 60kW a day, and assuming I could actually use 20kW's of that power rather than sell it back to the grid, I would "save" ~$60/month (our current rate is $0.09675/kWh) off my power bill. I would also receive "credit" for the surplus ~1200kWh/month @ ~$0.04/kWh = $48, for a total "savings" of $108/month.

If I could install the 20kW array for $5/W (I don't think this can currently be done), I would have an investment of $100,000. Assuming I could get 0% 15 year money, and received $30,000 in Federal Tax Credits and Managed to get ALL of the $10,500 State Tax Credits (virtually impossible), I would have $330.56 a month loan service on the $59,500 minus my $108 "savings", for a net loss of $222.56/month, or $40,600 over the course of 15 years. 31 years after the initial 15 year period (46 years total), the system would have "paid for itself". Obviously this bleak outlook would improve if electricity prices doubled or tripled over the term.

Current pricing on solar arrays is largely a function of "sub prime" silicone wafers purchased from the semiconductor industry. With modern IC makers' emphasis on higher and higher quality wafers, the price of "sub prime" keeps falling, and with it the price of solar cells. I think this trend will continue for some time into the future unless the growing of silicone crystals makes a giant leap forward, or the demand for sub prime wafers outstrips the secondary market. If the retail price /kWh reaches ~$0.25, and the cost of solar arrays drops to ~$2/Installed Watt, Solar becomes viable w/o subsidies.

Solar PV that is economically viable w/o subsidies is what I would truly like to see, sadly it pretty much requires electricity prices to double or triple. Right now, the only Home Owner Renewable Energy that has the potential to stand on its own is Solar Heat. I can make a good case for solar collectors & storage paying for itself in 10 years or less. When we built our house we oriented it with a 72ft x 25ft roof pointing due South. I had a heat exchanger installed in the HVAC system, and I have plans to install a solar collector array and a 2000 gallon Hot Water storage tank as soon as I have an extra $10,000. The system should supply 100% of DHW (Domestic Hot Water), 100% of the heat energy for my Hot Tub and >50% of our Winter Household Heat demand.

Our baseline consumption is 2200kWh/month, an estimated 1200kWh of which goes to generating heat. @ $0.10/kWh this is $120/month. (Obviously most of the savings is in the Winter). $10,000 @ 4% for 10 years ~ $100/month, leaving me +$20/month before any tax credits. Obviously a hot tub is a "luxury item" that makes the collection of heat a bit more viable (~$50/month average) in my case, but home heating alone in many areas may well make such a system worthwhile.

You mentioned looking into a heat pump, perhaps you should consider the addition of a solar heat collection system to go along with your solar PV array. If you augmented your heat pump with the solar hot water you could save as much as 1kW/M^2 of collector area (actual savings more likely ~500W/M^2). Evacuated Tube arrays cost ~$500/M^2 + Storage Tanks + Plumbing. Assuming 500W usable heat/M^2, this places the cost of solar heat @ ~$2/Installed Watt. That's a bargain!

If you went with a "Water Source" heat pump that used the solar heated water for its source in the Winter, and a well for its source in the summer, you could really save on heat/AC. Using 65F water for AC and 80F+ water for heat would make your heat pump SUPER efficient!

Sorry for the rambling, I just really enjoyed reading through this thread, and I obviously had a lot to say... Again, congrats on your amazing story; I only wish my State were willing to pay me to put in a solar array! With the Tax Credits and other incentives available to you in NJ, I think you made a great investment! I look forward to reading your updates in the future.

Fish

 

[mheslep]

Really it has more to do with the Solar installation & the car. If there were a "standard" battery voltage (12V, 24V, 36V, ... , 275V, 375V) then the task might be simply a matter of matching your grid tied inverter input voltage to your car's charging voltage, but you would still require a "charge controller" to regulate the current into your car's batteries, and really, an AC to DC charger is not much more or less efficient than a DC to DC charge controller.

Yes I suppose the scheme I suggest only works with panels dedicated solely to vehicle charging, as there always has to be a converter in the loop somewhere, whether DC/AC or DC/DC. In the case of dedicate panels, there need be only one converter, the one that will always come with the EV. Still that would be less expensive than charging a EV from a traditional solar system like Artman's here, which would be: panels -> DC/AC inverter -> house circuit -> car AC/DC converter -> car battery.

 

[Fish4Fun]

mheslep,

At the risk of hi-jacking this thread, AND arguing with someone who has invested over 2k posts on this forum, I would like to suggest that one of the "features" of EV's like the "Tesla" is the ability to charge "anywhere there is power". I cannot think of any way designing the car to be charged directly by a solar array would improve marketability of the vehicle.

The single largest problem I see with directly charging an EV from a solar array is the loss of any energy credits associate with the array (these are typically garnered from the inverter meter). The second major problem is that unless you primarily drive at night and sleep during the day, charging your car all day is not really practical. Ignoring these points, for the sake of argument, here is some data associate with the charging of the Tesla EV:Figures for the Tesla taken from their website:

Battery Pack Specifications:

Nominal Pack Voltage: 375V
Storage Capacity: 53kWh (141 1/3 AH)
Maximum Discharge Rate: 200kW (533 1/3A)

(Taken from http://webarchive.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf )

The High Power Wall Charger Specifications are as follows:

Maximum Current: 70A
Voltage: 208-240V, Single phase
Maximum Power: 16.8 kW

(Taken from: http://www.teslamotors.com/goelectric/charging/high-power-wall-connector )

A full charge is the energy equivalent of ~ 8 liters of gasoline, in today's market we will call that about $8. The charging time of the charger @ 16.8kW input is 4 hours (67.2kWh). We must assume the charging efficiency is 53kWh/67.2kWh = 78.9% and this efficiency likely represents a 88.8% converter efficiency and a 88.8% charging efficiency. At $0.10/kWh 67.2kWh = $6.72. I do understand your desire to cut the inverter out of the charging loop, but a grid tie inverter should be pretty close to 90% efficient, this would make the overall charging efficiency 78.9% * 90% = 71%.

Assuming 20k miles per year driving and the stated 245 miles/charge ~82 "full charges" would be required (obviously most charges would be "partial", and charging would occur daily) 82 * 67.2kWh = 5.5MWh/year. @ $0.10/kWh this = ~$550. The difference between 78.9% efficiency (a theoretical DC charge Controller + Battery Losses) and 71% efficient (Grid Inverter + Charger + battery Losses) would only amount to ($550/.71) - ($550/.789) = $77.56/Year. (Actually this number is a bit high, I should have used 53kWh, but the difference is trivial).

Compared to battery life (pessimistically 6 months, optimistically 3-5 years), any energy savings associate with charging would appear completely moot. @ ~$36,000, even a 36 year life span would place the cost of the batteries at almost twice the cost of charging.

Anyway, if you would like to continue this discussion, let's open a new thread to fully explore it rather than hijacking this very excellent thread on a Solar Installation. I certainly mean no disrespect to the thread starter, nor you.

Fish

 

[mheslep]

mheslep,

At the risk of hi-jacking this thread, AND arguing with someone who has invested over 2k posts on this forum, I would like to suggest that one of the "features" of EV's like the "Tesla" is the ability to charge "anywhere there is power". I cannot think of any way designing the car to be charged directly by a solar array would improve marketability of the vehicle.

The single largest problem I see with directly charging an EV from a solar array is the loss of any energy credits associate with the array (these are typically garnered from the inverter meter).

Yes, maybe so, but that's bookkeeping of subsidies problem, not a technical problem.

The second major problem is that unless you primarily drive at night and sleep during the day, charging your car all day is not really practical. Ignoring these points, for the sake of argument, here is some data associate with the charging of the Tesla EV:Figures for the Tesla taken from their website:

Battery Pack Specifications:

Nominal Pack Voltage: 375V
Storage Capacity: 53kWh (141 1/3 AH)
Maximum Discharge Rate: 200kW (533 1/3A)

(Taken from http://webarchive.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf )

The High Power Wall Charger Specifications are as follows:

Maximum Current: 70A
Voltage: 208-240V, Single phase
Maximum Power: 16.8 kW

(Taken from: http://www.teslamotors.com/goelectric/charging/high-power-wall-connector )

A full charge is the energy equivalent of ~ 8 liters of gasoline, in today's market we will call that about $8. The charging time of the charger @ 16.8kW input is 4 hours (67.2kWh). We must assume the charging efficiency is 53kWh/67.2kWh = 78.9% and this efficiency likely represents a 88.8% converter efficiency and a 88.8% charging efficiency. At $0.10/kWh 67.2kWh = $6.72. I do understand your desire to cut the inverter out of the charging loop, but a grid tie inverter should be pretty close to 90% efficient, this would make the overall charging efficiency 78.9% * 90% = 71%.

Assuming 20k miles per year driving and the stated 245 miles/charge ~82 "full charges" would be required (obviously most charges would be "partial", and charging would occur daily) 82 * 67.2kWh = 5.5MWh/year. @ $0.10/kWh this = ~$550. The difference between 78.9% efficiency (a theoretical DC charge Controller + Battery Losses) and 71% efficient (Grid Inverter + Charger + battery Losses) would only amount to ($550/.71) - ($550/.789) = $77.56/Year. (Actually this number is a bit high, I should have used 53kWh, but the difference is trivial).

Compared to battery life (pessimistically 6 months, optimistically 3-5 years), any energy savings associate with charging would appear completely moot. @ ~$36,000, even a 36 year life span would place the cost of the batteries at almost twice the cost of charging.

Yes I grant that the efficiency savings is small. As above, my point is that the solar array to charge a DC charged EV can completely do without the capital cost of an inverter at all. There are already pilot solar arrays so dedicated - Google has solar arrays to charge pilot EVs in its parking lot. Given all EVs charge off AC power right now, that means Google must have expensed an inverter - uselessly if the EV's could also handle a DC charge.

 

[Naty1]

Artman: Great project analysis and reports...

Time for another report. With Winter fast approaching and the days getting shorter, I've noticed a definite decline in energy production from the system. On what we would call a "Screaming Sunny Day" which is a cloudless, haze-less day our production is only about 30 (down almost 20 from Spring and Summer). It still peaks at a decent level during the height of the day about 7.5 kW to 8.0 kW out of 8.8 kW design.

Is this to be expected...or does it suggest a slightly different orientation of the panels might have been better...or neither?

 

[Artman]

Artman: Great project analysis and reports...

Thanks. I'm trying to keep you guys up to date.

Is this to be expected...or does it suggest a slightly different orientation of the panels might have been better...or neither?

Yes, it was expected. Our panel angle was around 40 deg, which is close to our Latitude, making it optimized for Spring and Fall. We had a cloudy fall so we've been using our reserve kW from the meter (We've dropped from around negative 1000 to around negative 500 in two months).

I went out and checked our sunlight at off-peak hours and I noticed that the panels are getting a lot of shade from tree branches early and late in the day with the shallow angle of the sun right now. So I imagine until we get past the Solstice our ratings will just continue to drop a bit. Still, overall the system built up a nice reserve prior to heading into winter and we're hanging in there enough on production to allow us to use electric unit heaters to supplement for comfort heating.

Fish4Fun, too bad about NC programs. They don't sound very conducive to putting in a system.

The single largest problem I see with directly charging an EV from a solar array is the loss of any energy credits associate with the array (these are typically garnered from the inverter meter).

This is not the case with us. We are under 10 kW at which point our production is estimated. We also have a commercial meter as part of the system in addition to the inverter so a reading can be taken of that if the Authorities change their method of accounting.

 

[Naty1]

Fish4:

(our current rate is $0.09675/kWh)

You sure that's the total cost about 10 cents per KWH, not just "distribution" or "supply" ?

When I looked at homes in New Bern, almost 2 yrs ago, I found the local electric rates were like NJ...about 18 cents per KWH...

 

[gmax137]

Oddly, just as I was reading the previous post, my wife handed me our current electric bill. Here in Connecticut, it's 13 cents for generation and 7 cents for distribution.

 

[mheslep]

Oddly, just as I was reading the previous post, my wife handed me our current electric bill. Here in Connecticut, it's 13 cents for generation and 7 cents for distribution.

Yep. What is going on up there? Virginia rates in cents/kwh are residential:10.6, commercial:7.5. and industrial:6.6. Connecticut's industrial rate is 2.15X higher than Va. How can Connecticut expect to have any kind of job base with power that expensive? I suppose having that new http://www.elp.com/index/display/article-display/3421342111/articles/electric-light-power/generation/natural-gas/2010/02/Deadly_explosion_hits_Connecticut_gas_fired_power_plant_.html" back in Feb. didn't help.

http://www.eia.doe.gov/electricity/epm/table5_6_a.html

Edit: more curious. Since 2000 Virginia's power company Dominion Power http://www.eia.doe.gov/cneaf/nuclear/state_profiles/connecticut/ct.html"

 

[gmax137]

...I suppose having that new http://www.elp.com/index/display/article-display/3421342111/articles/electric-light-power/generation/natural-gas/2010/02/Deadly_explosion_hits_Connecticut_gas_fired_power_plant_.html" back in Feb. didn't help.

Well, the rates were high before that, I'm pretty sure they've been high for years.

http://www.eia.doe.gov/electricity/epm/table5_6_a.html

Thanks, that's an interesting table. I'd like to know more about the reasons behind the variation from state to state, but that should be another thread.

 

[mheslep]

Interesting: this source shows New Jersey as the top ranked state for residential solar investment.
http://solarpowerrocks.com/reports/spr-report-card-2010-part-2-state-by-state-summary-grades/

 

[mheslep]

Price of solar continues to fall sharply. PV silicon panels per Watt, not corrected for inflation.
http://www.solarbuzz.com/Photos/moduleprices11-1.jpg

Year: $price, (% from prior yr)
Jan 2011: 3.38 (-13.7%)
Jan 2010: 3.92 (-15.6%)
Jan 2009: 4.65 (-2.3%)
Jan 2008: 4.76

 

[russ_watters]

"Continues to fall sharply" seems a little misleading to me. It looks to me like from that graph it went up for about 3 years in the mid-2000s. While I'm sure there is a general downward trend, it probably also reflects economic conditions, so I'd be shocked if the last two to three years of sharp downward trend continued.

 

[mheslep]

"Continues to fall sharply" seems a little misleading to me. It looks to me like from that graph it went up for about 3 years in the mid-2000s. While I'm sure there is a general downward trend, it probably also reflects economic conditions, so I'd be shocked if the last two to three years of sharp downward trend continued.

Maybe. But then looking at the full ten year period I'd be surprised if the -37% per decade declining trend didn't continue (5.4-3.4)/5.4. Also those prices are not corrected for inflation. So the 2001 price in http://data.bls.gov/cgi-bin/cpicalc.pl?cost1=5.4&year1=2000&year2=2010", giving a 50% per decade trend in real terms.

 

[russ_watters]

Maybe. But then looking at the full ten year period I'd be surprised if the -37% per decade declining trend didn't continue (5.4-3.4)/5.4. Also those prices are not corrected for inflation. So the 2001 price in http://data.bls.gov/cgi-bin/cpicalc.pl?cost1=5.4&year1=2000&year2=2010", giving a 50% per decade trend in real terms.

So a ten year interval is more useful than the 3 year interval from your previous post? Would the 10 year peariod from 1995-2005 give a similar figure? What was the decrease the previous decade? How long has this trend been going on?

I just get very antsy seeing stats and predictions like this because it's been an MO for enviro activists and bad reporters to misuse statistics to imply unlikely and even impossible advances in wind and solar power growth...not so prevalent as it used to be as those trends have mostly broken, but the internet it still littered with bad claims about advances in solar and wind. When a market - any market - is tiny and changing so fast, it is easy to get caught-up in misleading or even meaningless percentage changes. For example:

“Solar is now the fastest growing energy industry in the U.S., employing nearly 100,000 Americans and generating billions of dollars of economic growth for our economy,” President and CEO of the SEIA Rhone Resch writes.

By 2015, as you can see in the graph above, the solar industry is expected to grow several times over, perhaps even reaching a total of 10 GW of installed solar power capacity, enough to power 2 million homes.

“We can install so much solar energy that we will eliminate the need for any new coal or nuclear power plants in the U.S. ever again,” Resch writes.

http://cleantechnica.com/2010/10/13/solar-power-blowing-up-in-the-united-states/

Just please don't get caught-up in the same type of fallacy.

Here's an article from August of 2008 that seems to have accurately predicted the past three years of drop and also predicts we've already seen most of the drop expected by 2015 (ie, the next 5 years won't see anywhere near the drop of the last 3). And it may even level off by 2015

FOR 40 years or so, the price of solar panels fell steadily, as volumes grew and technology improved. But in 2004 Germany enormously increased subsidies for solar power, prompting a surge in demand. The supply of pure silicon, the main component of most solar cells, did not keep pace. Its price rose from $25 a kilogram in 2003 to as much as $250 this year, abruptly halting the downward march in the price of panels. If making energy from sunlight is ever to become as cheap as burning fossil fuels, the price of silicon will have to fall.

New Energy Finance, a research firm, expects the output of silicon for the solar industry almost to double next year. It has asked big buyers and sellers what prices they have agreed on this year for silicon to be delivered in the future. The responses suggest that participants in the industry expect prices to fall by more than 40% next year, and over 70% by 2015 (see chart).

http://www.economist.com/node/12010071?story_id=12010071

The accompanying graph shows the following silicon prices ($/kg):
2008 $200
2009 $120 -40%
2010 $90 -25%
2011 $80 -11%
2012 $70 -12%
2013 $60 -14%
2014 $55 -8%
2015 $53 -2%

Now I'm not sure what fraction of the cost is represented by the commodity but if the above ratios hold, it could be 40-50%. That means the overall drop in panel prices from 2010 to 2015 would be 13-17%, with prices going pretty much flat after that.

 

[mheslep]

So a ten year interval is more useful than the 3 year interval from your previous post?

Yes. That's >3x more data over time, so we have more a similarly increased confidence in its prediction power, but of course no guarantee that the trend will continue.

Would the 10 year peariod from 1995-2005 give a similar figure? What was the decrease the previous decade? How long has this trend been going on?

I don't have older data from the same source, but there is http://www.1366tech.com/v2/" going back to the 70s from a long time PV technology (not a manufacturer) researcher/MIT prof and entrepreneur, PV energy cost not power this time. He also presented the information in Congressional testimony:

I just get very antsy seeing stats and predictions like this because it's been an MO for enviro activists and bad reporters to misuse statistics to imply unlikely and even impossible advances in wind and solar power growth...not so prevalent as it used to be as those trends have mostly broken, but the internet it still littered with bad claims about advances in solar and wind. When a market - any market - is tiny and changing so fast, it is easy to get caught-up in misleading or even meaningless percentage changes.

I agree there's hype surrounding the business and claims warrant skepticism. The solarbuzz industry survey is the best (ie oldest, continuous, best known) I know of; I'm certainly open to counter data.

Here's an article from August of 2008 that seems to have accurately predicted the past three years of drop and also predicts we've already seen most of the drop expected by 2015 (ie, the next 5 years won't see anywhere near the drop of the last 3). And it may even level off by 2015
http://www.economist.com/node/12010071?story_id=12010071

Thanks, will look at that later.

Edit: take another look at the article. The Si fall is from a bubble, caused by the German PV demand driven by their subsidies that kicked in 2004 which caught production unprepared. The year before, in 2003, the price of Si was $25/kg.

The accompanying graph shows the following silicon prices ($/kg):
2008 $200
2009 $120 -40%
2010 $90 -25%
2011 $80 -11%
2012 $70 -12%
2013 $60 -14%
2014 $55 -8%
2015 $53 -2%

Now I'm not sure what fraction of the cost is represented by the commodity but if the above ratios hold, it could be 40-50%. That means the overall drop in panel prices from 2010 to 2015 would be 13-17%, with prices going pretty much flat after that.

Yes I read from some of the same sources that for Si PV panels, PV grade Si currently accounts for ~half of the cost of the total panel; perhaps it used to be much more. It's not clear from the Economist chart what form of Si they are pricing; semiconductors require very high (~99.9%) purity. Many of the historical technology improvements also correlate with the drop in price. Several of those impact the amount of Si required, or just increase PV cell efficiency (2X increase over ~20 years). For instance, the stock Si shipped to a PV mfn comes in the form of expensive http://upload.wikimedia.org/wikipedia/commons/thumb/5/59/Polycrystalline_silicon_rod.jpg/220px-Polycrystalline_silicon_rod.jpg" . The PV mfn then cut the ingots into PV cell wafers, wasting a substantial amount of Si as dust which can not be economically reused. Then came ultra thin wire saws (see the above PV energy chart), making the wafer cuts much more efficient, which would allow drop in the kWh per panel price, completely independent of stock Si prices.

 

[mheslep]

On the the Cleantechnica piece on SEIA:

“Solar is now the fastest growing energy industry in the U.S., employing nearly 100,000 Americans and generating billions of dollars of economic growth for our economy,” President and CEO of the SEIA Rhone Resch writes.

Don't know about fastest growing. Could be. The revenue in the billions must be correct, as the US market 2010 was market was that large in just panels alone, not including the fabrication machinery sales led by US giant Advanced Materials.

By 2015, as you can see in the graph above, the solar industry is expected to grow several times over, perhaps even reaching a total of 10 GW of installed solar power capacity,

I assume this refers to solar PV only, which is now ~1GWp total in the US, as solar PV plus thermal was already 8GW total a couple years ago. That requires a ~35% annual US installation growth rate to reach 10GWp cumulative in five years from the current ~1GWp. Given the http://en.wikipedia.org/wiki/List_o...ge_systems_in_planning_or_under_construction", along with residentials like Artman's here, I'd say 10GWp total by 2015 is likely.

enough to power 2 million homes.

Bogus. Not by solar alone, even if source is concentrated solar thermal with storage.

“We can install so much solar energy that we will eliminate the need for any new coal or nuclear power plants in the U.S. ever again,” Resch writes

Bogus x 2.

 

[Artman]

Bogus x 2

Yup.

Solar is currently only a supplement and can reduce the need for auxiliary coal plant operation. If enough solar installations are placed in operation it may prolong the time until the need to add more nuclear or coal generating plants, but the grid needs to meet its demand, even at night and cloudy days.

As of today our system is at 11,100 kWh and has exceeded design expectations by 100 kWh for the year. Still a few weeks left to generate before the anniversary of putting it online. We went online on the 21st of January 2010.

 

[WhoWee]

It's been 6 months - does anyone have any updated info?

 

[dlgoff]

It's been 6 months - does anyone have any updated info?

He's probably partying with all his energy savings money. But yea. Update please.

 

[David Morrow]

Hello all, first time here, am doing a research paper for undergrad degree. Renewable energy, here is my question, The power out of a small pv inverter is suppose to push its energy onto the grid past the net meter, how does this current get past the first step down transformer if that transformer has 7200 V coming into it from the other side?

 

[mheslep]

Hello all, first time here, am doing a research paper for undergrad degree. Renewable energy, here is my question, The power out of a small pv inverter is suppose to push its energy onto the grid past the net meter, how does this current get past the first step down transformer if that transformer has 7200 V coming into it from the other side?

The transformer can move energy in both directions. That is, the low voltage from you inverter is eventually stepped up the the HV side of transformer.

 

[Artman]

Wow, more than 6 months. Sorry about that. Time for an update.

It's been about a year and six months since we went solar. A few new things have happened: the electric company zeroed our meter on the anniversary date for our connection or there abouts. It's hard to tell from the records, we check our meter daily, but we apparently hooked up at a good time because we were nearly at zero then anyway, which is what you want. We were bouncing back and forth across the zero line for a few days.

We also put in a heat pump (more on that in a later post) and a heat pump water heater, and more insulation, so our house is all electric currently, with oil heat backup. With the addition of the more efficient HP and the HP H2O heater, we've been still gaining ground as we did last year through the year down at about 520 kWh below zero. Not bad, and comfort is great.

Got to go, more later.

Sorry it's been so long.

 

[dlgoff]

Wow, more than 6 months. Sorry about that. Time for an update.

It's been about a year and six months since we went solar. A few new things have happened: the electric company zeroed our meter on the anniversary date for our connection or there abouts. It's hard to tell from the records, we check our meter daily, but we apparently hooked up at a good time because we were nearly at zero then anyway, which is what you want. We were bouncing back and forth across the zero line for a few days.

We also put in a heat pump (more on that in a later post) and a heat pump water heater, and more insulation, so our house is all electric currently, with oil heat backup. With the addition of the more efficient HP and the HP H2O heater, we've been still gaining ground as we did last year through the year down at about 520 kWh below zero. Not bad, and comfort is great.

Got to go, more later.

Sorry it's been so long.

Thanks for the update. Can't wait to hear about your other improvements; especially the heat pump water heater.

 

[mheslep]

I see the SREC price for NJ continues to hold above $0.60 / kWh, by far the highest in the US, while the price has collapsed elsewhere.
http://www.srectrade.com/new_jersey_srec.php

 

[WhoWee]

Thanks for the update. Can't wait to hear about your other improvements; especially the heat pump water heater.

Yes, what type of booster is on the water heater?

 

[Naty1]

I just posted about a NJ alternative approach here:

https://www.physicsforums.com/showthread.php?p=3483872#post3483872


"I am having my home evaluatehttp by SunRun, Home Depot and bpsolar. There was a booth in a Home Depot store in NJ.

The "deal in brief": I supply the roof area for solar and they get permits, build, install, maintain and pay for the entire solar system. Then they sell me power under a 20 year contract at a discount to PSE&G power. Unless I have to modify my roof or replace shingles, there is no out of pocket expenditure for me."

 

[WhoWee]

I just posted about a NJ alternative approach here:

https://www.physicsforums.com/showthread.php?p=3483872#post3483872


"I am having my home evaluatehttp by SunRun, Home Depot and bpsolar. There was a booth in a Home Depot store in NJ.

The "deal in brief": I supply the roof area for solar and they get permits, build, install, maintain and pay for the entire solar system. Then they sell me power under a 20 year contract at a discount to PSE&G power. Unless I have to modify my roof or replace shingles, there is no out of pocket expenditure for me."

Are you replacing the roof now/first?

 

[Naty1]

I have to be a preliminary site evaluation, be approved to participate, then an engineering evaluation...I have no data yet so I am open.

I am going to post in the thread I started so as not to disrupt this great discussion...I am posting some interesting information as soon as I sign off here.

"Are you replacing the roof now/first?"

Depends on engineering evaluation and cost...in theory, I can remove and replace just the upper portion,south facing side, of my four roof surfaces. Roof shingles should be good for another 15 years or so I guess.

 

[Naty1]

I see the SREC price for NJ continues to hold above $0.60 / kWh, by far the highest in the US, while the price has collapsed elsewhere.
http://www.srectrade.com/new_jersey_srec.php

Can you explain your post...Looks like in September rates dropped to $167!, although I do not understand such a huge change...

 

[dlgoff]

Can you explain your post...Looks like in September rates dropped to $167!, although I do not understand such a huge change...

I'm glad you found this thread. I think you need to be careful with this:

...they sell me power under a 20 year contract at a discount to PSE&G power.

You will probably get very little savings. It might be better to rent a room.

 

[Naty1]

You will probably get very little savings.

could be,,,the Home Depot rep mentioned 15% to 20%...
I'm either "selling" anything here nor recommending anything, just posting whatever I learn.

The discount given to me must depend on the SREC rate the company gets from selling power to PSE&G. If I can save money over an extended time, I'm interested enough to check out the details but not whole heartedly enthusiastic at this point.

What happens for example if the company goes bankrupt or fails to maintain the installation?? I can easily visualize them disappearing as the life expectency of the installation approaches...

"It's all in the fine print."

 

[WhoWee]

could be,,,the Home Depot rep mentioned 15% to 20%...
I'm either "selling" anything here nor recommending anything, just posting whatever I learn.

The discount given to me must depend on the SREC rate the company gets from selling power to PSE&G. If I can save money over an extended time, I'm interested enough to check out the details but not whole heartedly enthusiastic at this point.

What happens for example if the company goes bankrupt or fails to maintain the installation?? I can easily visualize them disappearing as the life expectency of the installation approaches...

"It's all in the fine print."

No doubt. Do they require a minimum average usage or a guarantee of usage?

 

[OmCheeto]

"It's all in the fine print."

I would definitely scan in the contract and post it here. I can understand the tax incentive for businesses to own, and depreciate, their property, while selling you a commodity over a long term period.

http://www.youtube.com/watch?v=GVwWE_WOY0Q".

ps. I traded a solar panel installation(50 watts) for an air conditioner last week. But the damn kid said it would take him years for the system to pay off when I told him he'd have to invest $60 for a deep cycle battery. I was like; "Dude. I'm trading you a $250 solar panel for a $100 beat up old air conditioner... The sun shines during the day. You want to power your lights at night. You need a place to store all that energy. When the power goes out, due to a hurricane or something, you'll have the only house in the neighborhood with the lights still on. That's freakin' braggin' rights dude!". I'm still waiting on his response.

pps. don't know if you are a facebook kind of person, but the following made me smile yesterday:

https://www.facebook.com/oevadotorg...838638019.165959.138510433019&type=1&theater"

 

[mheslep]

Can you explain your post...Looks like in September rates dropped to $167!, although I do not understand such a huge change...

Yes that was back in July. The new data does show a huge drop in SREC price as you say. I can't explain the drop, but it highlights a concern with SREC options - no guarantee on the future price at which you can sell your solar electricity. Actually I suppose it was bound to happen. That state could not afford to pay out at 4X the price of regular electricity for too long. This drop is a point in favor of the 20 year contract people. The SREC prices become their problem not yours.

There are a number of companies doing these deals in the US. Until recently, the big ones have been on the West coast.Edit: Here's a backstory on PPA company SolarCity. There's been a lot of interest from commercial business in PPAs
http://www.technologyreview.com/tr35/profile.aspx?trid=970&mod=tr35_riverofnames
http://www.solarcity.com/commercial/portfolio/manufacturing/

 

[mheslep]

I'm glad you found this thread. I think you need to be careful with this:
You will probably get very little savings. It might be better to rent a room.

Why do you say this? His out of pocket is zero in a PPA, if he wants. Only concern that comes to mind is a turn over in the event of a house sale. But then, resale value needs to be considered for any modification done to the house, solar's no different.

 

[Naty1]

Actually I suppose it was bound to happen. That state could not afford to pay out at 4X the price of regular electricity for too long.

Iagree: That's the major thing I could not understand when I considered my own solar installation several years ago...that and well over $5/watt first cost at the time...it makes NO sense for government to subsidize relatively wealthy individual homeowners via tax credits and paying higher rates for electricity for otherwise uneconomical solar energy...somebody has to provide money to do that...those who pay regular electric rates. It's another silly big government waste.

Can you explain your post...Looks like in September rates dropped to $167!, although I do not understand such a huge change...

Yes that was back in July

Thanks, just wanted to check as I had not looked at rates in a long time...

Only concern that comes to mind is a turn over in the event of a house sale.

If a potential buyer gets an electric discount, it should be attractive; if not, I'm screwed. Another issue I posted in my own thread: any tax assesment on solar?? I don't remember...and that can always change.

 

[Naty1]

I just went to the official NJ website on SREC rates and there is no decline in rates reflected there:

http://www.njcleanenergy.com/renewab...g/srec-pricing

?


Some interesting SREC background here:

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

"In addition to providing cash flow security and stability, long-term SREC contracts are often required by banks or other lending institutions unwilling to accept market and legislative risk associated with SREC markets..."

 

[dlgoff]

Why do you say this?

Because of this.

"It's all in the fine print."