[Kosh]

Just saw this gem on tv:

PORTLAND - Construction began Tuesday morning on a solar energy station at the end of the TriMet MAX line near Portland State University.
 
The $370,000 Solarworld project is expected to produce more than 67,000 kilowatt hours of power each year.
 
TriMet said renewable energy generated by the solar panel system will go directly into Portland General Electric's power grid, offsetting the energy required to power electrical systems.
 
TriMet expects to get back about $3,680 per-year in energy credits.
 
Some critics say it will take TriMet too long to pay it off.
 
Solar energy experts say most solar panels have a lifespan of 20-30 years.

For a little background information Trimet is the local mass transit agency and usually does a pretty good job. The intent of this little project is to partially power the light rail. Beyond its cost problems, one other problem is reliability. Anyone who has ever been to the northwestern US knows that most of the year is rain, clouds and more rain, not much sunshine. 

[redsniper]

67,000 kilowatt hours of power

Uuuuuugggghhhhhhhhh..... Units?! Can anyone use them???

[Klaustrophobia]

what's wrong with the units? 

[Polpolion]

I closed the page the second time I was interrupted by an add, and at that point the only thing I saw wrong with the thing was "67,000 kilowatt hours of power per year". For those of you who haven't taken a physics class in a while, the Watt is the unit of power, equal to 1 joule of work done per second. When people say "kilowatt hours" they usually are referring to energy or work, but I'm sure it's nothing but bad reporting using power synonymously with energy.

As for the cost-benefit of all of this, I'm hesitant to say too much because I just don't know that much. The money saved per year, solar panel lifetime, and the total cost are probably all correct, but given the obvious lack of money saved I'm guessing most of that $370,000 is overhead that won't be needed to be re-spent when the panels are replaced. Course, I didn't watch the video so I could be totally wrong, in which case pls enlighten me.

[Wanderer]

Except kWh is the standard unit for energy when some one is billing you. Any one who has had to pay electric/energy/power bills is quite well aware of the fact. Joule happens to inconveniently small unit for anything but lab experiments (and it often is inconveniently large unit for those) and is based on inconveniently small unit of time.

[Polpolion]

All true. My qualm was that they called kWh a measure of power, not that they weren't using something like megajoules.

[Nuke]

kwh is watts*time. power is just watts. not an unusual mistake for a writer or reporter to make. there is a reason they're not engineers.

[Klaustrophobia]

in non-engineering/academic use, the terms "power" and "energy" are pretty much used interchangeably. 

[MarkN]

67,000 kWh per year is actually a correct unit within some parts of the power industry. Given that a year is 8760 hours (not accounting for leap years), this is a power output of 7 kW, or enough power to run 7 washing machines, 2 kettles or 1 storage heater. Of course it is enough to run 280 flouresant tube lights, but compared with real power plants, this is nothing. Even a wind turbine is usually 1000kW these days, while a small gas power plant would be 500,000 kW, and coal and nuclear plants are often 2-4 million kW. Add to that they could, with a little more investment get a linear Fresnel plant, or if they can get planning permission, a heliostat (or power tower) which would produce up to 10 times the maximum power output, still produce power (at a much reduced rate) when it is cloudy, and store power until it is needed. Unfortunately being microelectronics rather than heavy industry, solar panels are very fashionable)

Disclaimer: I work in the power industry, and the only sort of solar my company works on is using a heliostat (producing 10,000 times as much power as this installation)

[Turambar]

portland seems a little north to be very efficient at capturing solar power

[MP-Ryan]

portland seems a little north to be very efficient at capturing solar power

You'd be surprised, Oregon actually has a pretty favorable climate for solar energy capture.

[Polpolion]

in non-engineering/academic use, the terms "power" and "energy" are pretty much used interchangeably.

Would you call the construction of a large solar panel array a non-engineering use? If people want to be informed of how the technology their society runs on works, they should be using the terms correctly. Hell, they should be using the terms correctly all the time, but it's just plain stupid if they care enough to read/write news about power generation but not enough to know what power is.

[swashmebuckle]

I'm in Portland too, and whenever I look out my window, the two things that usually strike me are the overcast skies and the huge solar array on my neighbor's roof.  On the one hand, it was only a good buy for him because of the government subsidies, so I feel sort of ambivalent about it, but on the other hand, it put people to work during the recession and at least it isn't fossil fuels, though I'm sure a ton of those were burned during the production and installation of the equipment.

I feel like you sort of have to let the buzz ride on stuff like this though.  I sort of doubt that the alternative being considered was a modern nuclear plant or something else useful; it's probably this or nothing.  Considering the futility of most of our public works projects atm (this road needs another lane!), I'll take what I can get.  Until someone mans up at the national/international level and builds a high speed rail corridor to Seattle/Vancouver, we'll just have to settle for hippy **** like good public transit and bike accessibility.  Or maybe it's a Field of Dreams thing where we will get actual sunshine once they finish construction, in which case it's the best investment in Pacific NW history.

[LordMelvin]

Maybe it's a Field of Dreams thing where we will get actual sunshine once they finish construction, in which case it's the best investment in Pacific NW history.

If that works, put me down for three.

[Klaustrophobia]

in non-engineering/academic use, the terms "power" and "energy" are pretty much used interchangeably.

Would you call the construction of a large solar panel array a non-engineering use? If people want to be informed of how the technology their society runs on works, they should be using the terms correctly. Hell, they should be using the terms correctly all the time, but it's just plain stupid if they care enough to read/write news about power generation but not enough to know what power is.

no, but an article mentioning it to the general public is non-engineering use.  this is really not a big deal.

[Polpolion]

The people that don't know the difference may not mind, but I'd like my news to tell me things that are correct. 

[Kosh]

portland seems a little north to be very efficient at capturing solar power

You'd be surprised, Oregon actually has a pretty favorable climate for solar energy capture.

Yes, having lived here for most of my life makes it surprising for me too. Half the year is usually almost nothing but clouds and rain.

For those of you who also dont know, 3/4 of Oregon's electricity comes from hydro, one of the only two renewables to have ever been economically competitive and dependable (the other being geo). Solar is dramatically more expensive.

On the one hand, it was only a good buy for him because of the government subsidies, so I feel sort of ambivalent about it, but on the other hand, it put people to work during the recession and at least it isn't fossil fuels, though I'm sure a ton of those were burned during the production and installation of the equipment.

Those subsidies wont last forever, like all artificially inflated markets renewables will have their reckoning.

[Bobboau]

$370,000
$3,680 per-year

ok, so in about 100 years it will have paid for it's self.

except if you factor interest into things it would have like 54 million by that time.

[Al-Rik]

Solar is dramatically more expensive.

Well, the main benefit is that anyone who has enough money can put some panels on his roof and get money from the government for it.

It's much better than a paying a greedy big company a fair and lower price for energy, because the greedy company doesn't make profit or isn't it ? 

[redsniper]

Oh god dammit. MarkN puts me to shame. kW is power (the time rate of energy), so multiplied by time makes it energy, kWh, but then divided over a year and it's back to power. Derp.

Well fine. I'll still wager that the guy writing the article didn't know any of that.