The Lightbulb Goes On!

[elfs]

Across the street from the incubator is the Pemco insurance building, and one of the big deals is this sign on the side that proclaims in big letters, "The solar panels on the roof of this building are generating 3.3KW of power!" And I used to wonder, exactly how much power is that? What is that in meaningful terms?

Today, it's a grey day and the sign is showing a pathetic "0.11KW of power." And then it hit me: holy chao, that's 110 watts. That's two lightbulbs. The proud LED sign braying out how much energy they're generating probably takes more power to run than the solar cells generate.

Comments

[herewiss13.livejournal.com]

I haven't done the math, but to be fair: LED lights are a _lot_ more efficient than normal bulbs.

[gromm.livejournal.com]

Let's just assume that those LEDs are 3W each then (which are some of the brightest around, by the way - for comparison, 1W is typically what each bulb in an LED flashlight provides). That means there can be no more than 36.6 LEDs in that sign to break even on a day like today. Or maybe 110, but I'd bet on the former number. If you use CFL bulbs, then that comes out to about 10 light bulbs by the way. ;)

As for what 3.3Kw in meaningful terms is... well, your dryer is probably between 4.5 and 5.5Kw. It would be a much better idea to dry your clothes on a line than to use solar panels *that* way. ;)

Your TV is probably around 200-300 W, and your computer probably between 100 and 250 W depending on what it's doing (I measured that with a kill-a-watt, by the way). Unless the dryer (or the stove, if it's electric) is on, 3Kw is considerably more than your house will draw at any given moment in time.

For example, my house averages about 20Kwh per day in the summer, without AC (according to my hydro bill, which gets that average from two months of usage divided by X days in those months). My dryer probably uses about 1/3 of that, the fridge about 1/3 of that (it uses less when it's on, but it does it way more often), and the rest is light and electronics.

So when it's cloudy, yes, those solar panels produce SFA. When it's sunny, it really does matter.

Oh, no

[ideaphile.livejournal.com]

There's no way in heck those LEDs are consuming 3W each! They're probably more like 20 mW.

If I'm correct in estimating the sign has 32 x 80 LEDs, its peak power consumption is probably around 50W for the illumination, with the average more like 20W given the usual ratio of on-to-off pixels.

I suspect the system controller consumes a lot more than that, but if the whole thing consumes more than 100W average, I'd be surprised. Looking around online, indeed, that seems to be about right for various commercial LED signs.

So 100W continuous is 216 WH over the course of three months-- only a little more than a quarter of the energy generated by the solar cells in the same time.

And I gather Pemco had the sign before the solar panels anyway, so the panels are really a separate issue.

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Re: Oh, no

[gromm.livejournal.com]

Sure it's possible (http://www.mec.ca/Products/product_detail.jsp;jsessionid=1w6DLV9fF09XyRp12s2HhjncyBlnPwjThmnGTLTk2ZW8myLGlB14!-825556489?PRODUCT%3C%3Eprd_id=845524442629488&FOLDER%3C%3Efolder_id=2534374302696981&bmUID=1259732479153).

But then, I haven't seen the sign either.

Re: Oh, no

[ideaphile.livejournal.com]

A sign made of those superbright LEDs would need water cooling and radiators as large as Pemco's solar array! Plus it would blind everyone who looked at it.

Also, mine (http://www.amazon.com/dp/B001H4MWA4) are brighter (http://www.amazon.com/dp/B0020XF0JQ). :-)

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Solar Pie and the PEMCO solar roof

[(Anonymous)]

Hello Elf,
Thank you for entering into the conversation about solar energy in Seattle. When Solar Pie partnered with PEMCO Insurance to put on the solar array it was to create this kind conversation about solar energy. Our hope was to give people in Seattle a platform to experience solar energy real time. Most people would not expect that any power would be made on cloudy, rainy and dark Seattle days. The sign will broadcast a solar production number until sunset. Most days you will see the production number go to .10 kWh of solar production.

The Solar Pie solar roof array atop the PEMCO building produced 8,000kWh of safe, clean and renewable solar power to date. The solar energy produced by the PEMCO solar array would provide 88% of the power for the average Seattle home. In addition the PEMCO roof has prevented 13,600 pounds of carbon from being released into the atmosphere. An added benefit is that 200,000 cars pass by that roof every day. It is our hope that those who see the sign are like you and engaging their mind and asking questions.

We have many challenges before us as we look to the future. Our goal is that we work every day toward a future that is powered by the safe, clean and infinite power of the sun. A good question is how do we get there from here? What do we do on days when the solar production is low? How do we store this energy for night-time use? How do we meet these challenges? How can we together shape a better world? These are big questions. It is our hope that this partnership with PEMCO is a step toward that better world.

I have included the mission and vision statement for Solar Pie:
Solar Pie Vision Statement
– Creating a safe clean sustainable energy future for the United States through the adoption of solar power.
• Solar Pie Mission Statement
– Solar Pie accelerates the adoption of solar technology nationally by expanding awareness of the efficacy of solar power. Solar Pie advocates, facilitates and promotes the installation of awareness building solar arrays by corporate partners. We do this through a replicable process in which we:
– Identify and engage corporate partners with visible roofs
– Provide expert consultation to facilitate the solar installations
– Maximize awareness of each project and the energy it generates
– Engage Communities via web based tools
– We use these projects to demonstrate that solar power is a safe, clean, sustainable energy source achievable for the majority of people living in the United States. We thereby translate solar power from an idea to a widely used and accepted source of power.

Thanks again for engaging in the conversation, we invite you to join us.
Carolyn & Scott Sherwood
Co-Founders-Solar Pie
http://solarpie.org/

Re: Solar Pie and the PEMCO solar roof

[ideaphile.livejournal.com]

So that whole thing, which reportedly cost $100,000, has generated a total of $800 worth of electricity in three months?

Call it $3,200 per year-- that's a 30-year payback period, which is to say, it's a huge net loss in every way.

And if the $100,000 figure includes the effect of any government subsidies (most solar systems do), the real payback period from the perspective of Planet Earth is actually longer.

Solar's great for San Diego, but grossly irresponsible in Seattle.

If you people cared about the environment, you'd take that system down from the Pemco building and ship it off to someone in Phoenix or Albuquerque where it'll generate-- well, I don't know for sure, but probably at least four or five times as much energy over its lifetime.

It sounds like you're doing solar because you want to APPEAR environmentally sensitive. Liberal guilt strikes again.

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Re: Solar Pie and the PEMCO solar roof

[(Anonymous)]

Hello ,

Forums for discussion are valuable because you have an opportunity to share your thoughts and listen to feedback from others. Often times you come away with a new and slightly different perspective.

We both agree that a clear sky is better for making solar energy. But that is one factor in solar production. Temperature is a second factor. It may on the surface seem like the simplest of solutions to put all of the solar panels in the Southwest however the solar panels on top of the PEMCO building perform best at 77 degrees. Warmer than that..say a baking hot summer in Phoenix or Albuquerque just when you think you would be racking up the solar production numbers the panels will be much less efficient . Solar in Seattle will outperform Phoenix or Albuquerque during the summer. While more sun is better that is no reason to throw away the sun’s energy that falls on Seattle. It is not either or, it is both.

Semiconductors are priced on what is known as the learning curve. The first unit cost is way out of proportion to the total costs. But those early costs have to be incurred to get to the total. The first PC we bought cost about $15,000 (very small hard drive). That is a reflection of the PC when it was in the innovator or early adopter stage in market acceptance. If no one spent that money the market would not have matured. In 1984 GPS systems cost $12,000. Today you can by a smaller, faster, better and far less expensive GPS for $159. Was it wrong to have purchased a $12,000 GPS system in 1984 or a $15,000 PC in 1983? If no one had developed either marketplace we would not have $500 laptops with internet and 200 gigabyte hard drives.

Your point about the cost is exactly why the awareness and knowledge building from the PEMCO roof display is so important. It is a part of creating the marketplace for solar where market forces can drive the cost of solar down just as it has for PC’s, GPS, Printers. Flat Screen TV’s, Digital Cameras, and Internet Access. In the three years since we installed the solar array on our home prices have fallen by a third.

The market for solar is in its infancy less than ¼ of 1% of the energy produced in this world comes from solar technologies. Why would we ever expect such an immature market to be priced or behave as a mature market? Our goal is to have some small part in driving down cost of solar so it is within reach of everyone.

Lastly, every ton of carbon saved is an improved chance for survival. Solar is a safe, clean and infinite energy source. It is all good.

Best,
Carolyn & Scott Sherwood
Solar Pie

Re: Solar Pie and the PEMCO solar roof

[ideaphile.livejournal.com]

While the efficiency of the panel may drop slightly at higher temperatures, that's a red herring; shame on you for bringing it up.

We're talking about the difference between (say) 13% of Seattle sunlight and 11% of Tuscon sunlight-- that is, more sun is always better.

You must know that. Why the attempt to mislead?

You are not collecting "the sun's energy that falls on Seattle". You're only collecting the sun's energy that falls on your solar array. There would be vastly more energy collected in other places.

Yes, it is "either"-- either the array is in Las Vegas or it's in Seattle. Never "both."

Yes, people bought early, expensive products in other markets, and that helped those markets develop. But you're effectively trying to grow THIS market using heavy doses of fertilizer and pesticides. It is not growing naturally.

We can "save" tens to hundreds of times as much carbon by spending all this solar development and subsidy money in other ways. Carbon is a ridiculous metric for comparing energy sources, anyway. It has nothing to do with "survival."

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