ECN Forum Forums General Topics of the Trade General Discussion Area Yearly household usage in kWh

I use about 30 kwh(higher in winter, lower in summer) a day. Solar hot water with Electric back up, Hot Tub in basement,oil fired furnace,laptops, tvs, lights, satelite recievers etc. Just came home and the TV was on and no one was home. 11 yr old left it on when he left for school

It's hard for any discussion about power NOT to get political, because the issue of power has become so politicized in recent decades.

Discussions about power outages can especially become very political, which is why I refrain entering those discussions whenever they are brought up. I might have plenty of knowledge and insight, instead I just keep my mouth shut for this reason. But it's impossible NOT to bring up politics, when politics is SPECIFICALLY what prevents the things necessary to bring and ensure reliable power distribution such tree trimming, building of new power plants, installation of new lines, and so forth... all of which are typical causes of power outages.

Without power, none of us would have jobs. Period.

I wish none of this were the case, and sparkys could just toil away doing what they do best... but as long as politics inhibits us from doing what we need to do - which is essential for a modern society - how can we NOT bring it up?

Nonetheless, my apologies if my post crossed the line.

Joe

I can not agree as the topic here is not power production.

The topic is how much power do you use?

You seem to have a very strong view of power production and have tried to infuse that in at least a couple of threads.

I get along fine in a few electrical forums without going political I ask that you try to do the same.

Bob

This is no longer true. New a-Si PV cells have full energy payback in as little as 2 years, and flexible polymer cells are being developed that are even cheaper, both in terms of dollars and energy.

It's still wildly impractical as prime power, though.

* Average Solar Flux for North America: 150 W/m[super]2[/super] -This is representative of the US Northeast and Europe, and accounts for weather.
* Best Average Solar Flux in the US southwest is 240 W/m[super]2[/super]
* Northern US December average 71 W/m[super]2[/super]
* Winter levels will be appx 80% of this value
* US Annual Energy Consumption in 2003: 6.22 ExaWatt-hours (equivilent to 325 billion tons of oil)
* Typical electrically heated household energy use during coldest week of winter: 24,000W
* Typical instantaneous power requirement for a refrigerator: 1200W
* Combined contribution of solar, geothermal and wind in 2003: less than 2%
* Solar Panel Efficiency: 8.25% (commercially mass produced a-Si, the only feasible material at the scale we're talking! See Unisolar whitepaper #1 below.)
* Thermal de-rating of solar panels for US winter weather: 15% for a-Si, 35% for crystalline silicon.
* Typical loss due to dirt, dust, etc: 3%+
* Inverter efficiency: 94%
* Wiring efficiency: 97%
* Transformer efficiency: 95%
* Battery efficiency: 80%

* Energy required to manufacture a-Si panels:120 kWh/m[super]2[/super] (432 MJ/m[super]2[/super]) as a generously conservative estimate. I don't know if this counts mining, refining, transportation, installation, cabling, power conversion, substations, transmission, etc, etc and I'm pretty sure it doesn't.
* Energy required to mount an a-Si panel: appx 120 kWh/m[super]2[/super] (432 MJ/m[super]2[/super])

* Solar energy absorbed annually per m[super]2[/super] in US Southwest desert:
365 days * 24 hours * 240W/m[super]2[/super] = 2,100 kWh

* Solar energy absorbed annually per m[super]2[/super] in US Northeast:
365 days * 24 hours * 150W/m[super]2[/super] = 1,314 kWh

* Losses in conversion, wiring, etc:
.97 * .94 * .97 * .95 * .80 = 32% loss, 67% efficiency

* Break-even point for energy for a-Si Solar Panels and installation in US Southwest desert:
240kWh/m2 / (240W/m2 * 8.25% * 67% * 24 * 365) = 2.1 years

* Break-even point for energy for a-Si Solar Panels and installation in US Northeast:
240kWh /m2 / (150W/m2 * 8.25% * 67% * 24 * 365) = 3.2 years

For this that missed the significance of this, it means spending 2-3x our entire annual energy consumption on solar panel production alone.

If the south-facing roof of a 200m[super]2[/super] (~2000ft[super]2[/super]) typical house in the Arizona desert was covered in a-Si solar panels:
240W/m[super]2[/super] * 100 m[super]2[/super] * 8.25% * 67% = 1300W (about enough to run a refrigerator)

If the south-facing roof of a 200m[super]2[/super] (~2000ft[super]2[/super]) typical house in the US was covered in a-Si solar panels:
150W/m[super]2[/super] * 100 m[super]2[/super] * 8.25% * 67% = 829W (about enough to run a typical PC desktop with 17" CRT monitor). It would take 42 houses like this to provide the energy one house requires for electric heating.

If the south-facing roof of a 200m[super]2[/super] (~2000ft[super]2[/super]) typical house in the US Northeast in winter was covered in a-Si solar panels (assuming no snow):
71W/m[super]2[/super] * 100 m[super]2[/super] * 8.25% * 67% * .85 = 321W (4 houses combined could run a Mr. Coffee). It would take 75 houses like this to provide the energy one house requires for electric heating.

Cost of 8% efficient a-Si solar panel: appx $1000/m[super]2[/super]
Cost of installation: appx $100/m[super]2[/super]
Cost of 10kW inverter: $12000 (For surge. An electric range draws 10kW.)
Cost of storage batteries: $200/kWh
Cost of cabling: appx 1x material cost
Cost of electrical installation: appx 2x electrical material cost

100m[super]2[/super] of solar panels: $100,000
Cost of panel installion: $10,000
Batteries required to store 2 day’s worth of energy at 1300W average: $13,000
Cost of inverter: $12000
Cost of electrical installation: $20,000
Total cost of 1300W Arizona or 564W northeast partially-solar-powered house calculated for above: $155,000.

Area of solar panels in the southwest US desert required to supply US with total electricity demands:
6.22Ewh / (1300W * 24 * 365) = 54,000 km[super]2[/super]

Number house-sized solar panels spread evenly throughout the US required to supply US with total electricity demands:
6.22Ewh / (829W * 24 * 365) = 856 million house-sized panels (compared to 120 million households in the US, which includes aparments and townhouses)- works out to about a quarter acre of solar panels per every family in the US. BUT, that's lopsided as most of that comes from the summer. If we go by straight winter values, it works out to closer to 17 acres of solar panels per family.

US GDP: $ 11.75 trillion
856 million house-sized panels: $158 trillion


Sources: http://www.eia.doe.gov/emeu/cabs/usa.html http://www.johnstonsarchive.net/environment/solartechnote.html http://www.uni-solar.com/uploadedFiles/0.4.2_white_paper_2.pdf http://www.uni-solar.com/uploadedFiles/0.4.2_white_paper_1.pdf http://www.nrel.gov/docs/fy04osti/35489.pdf http://en.wikipedia.org/wiki/Solar_power


Since we're using very large numbers here:
1,000 Thousand Kilo k
1,000,000 Million Mega M
1,000,000,000 Billion Giga G
1,000,000,000,000 Trillion Tera T
1,000,000,000,000,000 Quadrillion Peta P
1,000,000,000,000,000,000 Quinillion Exa E

* It would literally take a solar panel larger than Wales to supply UK with their annual electrical consuption. And probably require most of Scotland to be turned into hydoelectric resevoirs to feed the grid at night and on rainy/cloudy days.

http://www.eia.doe.gov/emeu/cabs/usa.html
In 2003, the United States generated 3,848 billion kilowatthours (Kwh) of electricity, including 3,691 billion Kwh from the electric power sector plus an additional 157 billion Kwh coming from combined heat and power (CHP) facilities in the commercial and industrial sectors. For the electric power sector, coal-fired plants accounted for 53% of generation, nuclear 21%, natural gas 15%, hydroelectricity 7%, oil 3%, geothermal and "other" 1%. During the first eight months of 2004, electric power generation rose about 2.2% year-over-year.

Natural gas-fired power generation has greatly increased its share of the U.S. power mix over the past few years, from just 9% in 1988 to 18% in 2002, although it fell back in 2003, to 16%, due in large part to higher gas prices during 2003. Investment in coal-fired power generation generally has been less attractive than natural gas in recent years due to relatively high capital costs and longer construction periods. As a result, coal's share in the U.S. power mix has fallen from 57% in 1988 to 51% in 2003. The share of nuclear power generation in the U.S. power mix has remained relatively flat over the past 15 years or so, increasing slightly from 19% in 1988 to 20% in 2003. Oil's share has fallen from 5% in 1988 to 3% in 2003.

On a national level during 2003, the retail price of electricity averaged 7.40 cents per Kwh, up 2.6% from 7.21 cents per Kwh in 2002. Electricity prices in the United States fell every year between 1993 and 1999, but this trend reversed in 2000, 2001, and 2003. For the first eight months of 2004, electricity prices were up 1.7% year-over-year, to 7.57 cents per Kwh.

As of 2002, U.S. net summer electric generating capacity was 905 gigawatts (GW). Of this total, 76% was thermal (35% coal, 19% natural gas, 18% "dual-fired," 4% petroleum), 11% hydro, 11% nuclear, and 2% "other renewables" (geothermal, solar, wind). The amount and geographical distribution of capacity by energy source is a function of, among other things, availability and price of fuels and/or regulations. Capacity by energy source generally shows a geographical pattern such as: significant nuclear capacity in New England, coal in the central U.S., hydroelectric in the Pacific West, and natural-gas-fired capacity in the Coastal South.


the EIA's electricity numbers :

I must take exception to the statement that I've tried to "infuse" my views on power production into threads. All I did was respectully respond to TWO OTHER posts that specifically mentioned solar energy. Now if I went on a rant about solar energy when it wasn't even mentioned, then you'd have a point.

But please tell me how it's NOT political to start a thread comparing US electric consumption versus other countries - the underlying premise being we consume too much power??? That is EXTREMELY political! But apparently you didn't seem to have a problem with that.

I guess certain views are acceptable here, while others aren't (like mine) which is fine, this is a private forum and as moderator you decide who and what stays or goes. But to claim that I was "infusing" something I was not just does not appear genuine, but that is fine.

No need to respond to this aspect of the thread any further... I get it... feel free to delete and/or ban if need be.

Joe

My interest wasn't in saving the world or really even saving any money. I was just thinking about keeping my pool blue in an extended power failure. I can live without AC if the pool is working. The solar to run it is going to be close to what it cost me to build it in the first place.

I am still thinking about this problem but the model doesn't look like it's going to be the normal inverter/battery deal. I am thinking about a DC pump motor running directly off the array now.

IMO, it is not about this board being political, it is about this particular thread, which is about ones power consumption.

The bill from the utility tells me we (two people in an apartment without gas) use just over 1 000 kWh/year. This does not include the hot water and the heating as both of these come from the district heating. (The electricity cost has gone through the roof and is now nearly US$300 per year, all included!)