Archive for December, 2007
$1 per watt solar panels
On December 21, 2007 in Uncategorized
Found this on Slashdot today:
“A Silicon Valley start-up called Nanosolar has shipped its first solar panels — priced at $1 a watt. That’s the price at which solar energy gets cheaper than coal. While other companies have been focusing their efforts on increasing the efficiency of solar panels, Nanosolar took a different approach. It focused on manufacturing. ‘The company [has developed] a process to print solar cells made out of CIGS, or copper indium gallium selenide, a combination of elements that many companies are pursuing as an alternative to silicon.’”
According to InfoWorld, Google is backing them. This is great because google has so much damn money that they might be able to make the shove needed to once and for all bring the cost of solar electricity down significantly.
Unfortunately it doesn’t look like we will be seeing $1/watt photovoltaics any day soon, because the first commercial panels will become part of a Nanosolar exhibit; the second will be auctioned off on eBay; and the third will be donated to the Tech Museum of Innovation in San Jose, from what this news.com article says. In the same article, it mentions that
“In a previous interview, Roscheisen said all of Nanosolar’s anticipated production in 2008 has already been ordered.“
So it looks like it will be at least 2009 before I can get my hands on these $1/watt solar panels they are raving about..
Solar Space Heater
On December 16, 2007 in Uncategorized
Working on the solar space heater design a bit more I came across a program called CoDePro on the University of Wisconsin Madison’s website, which is a collector design program that supposedly makes it easier to design collectors, calculate efficiency curves of the collectors in various conditions, and compare this data to experimental data. I will install it later today after some Christmas shopping, and see how it works.
On the design side of things, I am leaning towards a flat plate type collector outside with the old water heater tank actually acting as a storage tank in the closet of the bedroom this heater will be going in. The cast iron radiator I have will be going in the bedroom itself.
The way the house was built, it should be possible to have the collector below the tank, and the radiator above it. Thinking of mounting the tank horizontal-ish on the floor of the closet, with the radiator elevated about 2ft above the floor. With the collector mounted on the side of the house at near ground level, thermosyphoning should take care of the fluid transfer. I’d rather not have to set up a PV panel with a pump.
Here is a crude MS Paint drawing I just whipped up:
I’ve been trying to decide what kind of collector I want to build though. Right now it is looking like a single pane glazed collector with tube/fin construction will fit the bill. While hunting for info on constructing these types of collectors I found some good information on tube spacing and header construction at www.solarexpert.com:
“Optimum tube spacing. Wide spacing of tubes reduces collector cost, while close spacing increases cost, but improves efficiency. Fin efficiency drops rather fast as the tube spacing is increased above about four inches, depending on the thickness and thermal conductivity of the fin metal, and effectiveness of thermal bond. The highest quality, most cost effective collectors have sufficient spacing typically no more than 4 inches, with large area tight bonding to the water tubes.
Another highly desirable design and construction feature is secure attachment of headers to water tubes. High quality collectors have the tubes brazed or welded to the headers and supported mechanically by insertion into sockets extracted directly from the header metal by a “t-drill”. In addition to high level insurance against leaks, and breakage at joints and from wind vibration, this method of attachment provides smooth easily balanced flow and eliminates the possibility of eddy corrosion.”
“The flow rates required in glazed collectors are lower so smaller headers are permissible without degradation of quality. Serpentine arrangement of water tubes should be avoided in both glazed and unglazed collectors, in favor of parallel grid arrangement of tubes. Efficiency is reduced in serpentine collectors because the average collector temperature will be higher from the repeated passages through the collector. For an 8 tube collector, the pressure drop will be 8 times as high in a serpentine collector as in a parallel grid collector for the same flow rate and tube size. It is also extremely difficult to purge all air from a serpentine collector, which is essential to proper fluid flow and heat transfer. Conversely, no special air purging is needed for a parallel grid collector because the air will rise to the top header of its own accord to be purged automatically by the air vent.“
The collector case will need to be highly insulated to prevent heat loss. Along with this, all pipes coming into/out of the collector will need to be insulated, and the pipes need to not come in contact with the case. If the pipes or the collector plates/tubes come in contact with the case, there can be a dramatic loss in heat through conduction, so make sure to not use heat conducting materials to support or attach the collector, as well.
I have moved away from the batch style heater, because I would like this to perform well in moderately cold winter temperatures, and the batch style heater will not suit that situation like a flat plate liquid based collector will.
Here is an image I found on backwoodshome.com
This image makes in a good point, in that you don’t want to use the standard cold water inlet on the top of the tank if you are setting up an old water heater as a tank and plan to move the fluid using a thermosiphon. On top of that, it looks like a good design and I will take it into account when putting the finishing touches on my design.
Looks like 3/8″ copper will be the tubing I use for the collector, and I will solder that to flat copper plates.
Paypal Donations
On December 07, 2007 in Uncategorized
Well folks, first donation was a cool $10 (THANKS!)
As soon as the money is transferred (paypal says it will be 4 days) I will get my new hosting set up, and solardiy will be solar powered!
Thanks again, I will try to add as much content as possible over the next few days but keep in mind that next week is finals week
Solar Investing
On December 07, 2007 in Uncategorized
There have been some interesting news articles regarding solar related stock prices in the past few days. I took a look at them and had some thoughts to share.
To start:
“Solar-product stocks rose Friday as analysts upgraded shares and lifted profit estimates for companies on expectations of more polysilicon supplies and strong demand next year.
Investors were also encouraged by news that the House of Representatives passed a long-awaited energy bill Thursday evening, although analysts noted that its implementation is far from guaranteed. The Senate has yet to approve the bill, and President Bush has threatened a veto if it is passed as it now stands.
Banc of America Securities analyst Eric Brown upgraded Yingli Green Energy Holding Co. to “Buy” from “Neutral,” based largely on stock value. However, he also said lower silicon prices, combined with the company’s low-cost structure, will help earnings next year.”
Full article: Solar-Product Stocks Gain from chron.com
The bill they are referring to is the same “Energy Bill” blocked by the Senate. As the article says, the bill made it through the House of Representatives despite the veto threat from Bush, but stalled out in the Senate today, needing only 7 more votes to pass.
“The centerpiece of the bill is a requirement that passenger vehicles sold in the United States achieve a fleet average of 35 miles per gallon by 2020, the first significant increase in mileage standards since 1975.“
Sounds good to me, but 35 miles per gallon still sucks. My girlfriend’s bone stock Toyota Corolla 4dr gets that even in city traffic.
Back on track though, here is an article about First Solar Shares Sliding. Apparently they fell more than 6% on Tuesday. They are hoping to bring it back up though by breaking into the US market, apparently starting with the acquisition of Turner Renewable Energy LLC last week. Keeping my eye on this one.
On the other side of things, it would make sense to expect Trina Solar stock prices to rise, after they announced Wednesday that they has signed a development agreement with a Chinese municipality for a polysilicon production facility, set to be completed by 2012.
Again though, to change directions, here is an article about Solar Cell Maker Shares Slipping. This seems to be a result of an analyst ‘predicting’ that the energy bill referenced above was not going to pass.
It is very interesting to see how the prices rise and fall day to day. Hopefully this info helped someone out with their portfolio
Designing a Solar Heated Structure (Part One)
On December 06, 2007 in Uncategorized
Apologies for the stagnation of the Solar Cabin construction. While I lay in waiting for materials and capital, I have been doing lots of design work. As I was running through calculations and doing research, I realized how daunting this might be for many people looking to approach this from a “Do-It-Yourself” standpoint.
And from that random though comes “Part I” of my step-by-step guide to designing a solar heated structure:
“Designing a Solar Heated Structure“
When heating a structure using a “direct gain passive solar” system (direct gain means the space is directly heated by the sun) There are many different aspects that need to be considered. Initially, it is good to come up with a plan consisting of a rough sketch of your ideas, and any important details you think of as well. As the plan progresses, and you do more calculations and design, the plan can be developed into something more detailed and defining of the structure to be built.
In the beginning, you will need to consider the basics of Direct-Gain Solar Design. It is important that the structure be placed such that it gets maximum sun exposure to the collectors (in this case, the windows), The collectors need to be appropriately sized for the space, and there needs to be sufficient thermal mass to store heat, as well.
Of course, heat loss cannot be discounted. Attention needs to be paid to insulation, as well as infiltration and the heat loss through walls, windows, doors, ceilings, floors etc. Here is an excellent article on heat loss in buildings from engineeringtoolbox.com that will be used later on in the “guide.”
For now, though, we will concentrate on site selection and interior layout; two very important steps in designing a solar heated cabin, home, or commercial/industrial building. If the building’s location and orientation are not factored into the construction, the so-called solar heated structure will likely be a disaster. “Measure twice, cut once” and all that..
In the winter, the sun is low in the sky during the evening hours, causing the northern side of a building have little in the way of “solar gain.” Because of this, a solar heated building will benefit from having most of the “heat collectors” on the southern exposure of the building, and the smallest possible size northern exposure. Most decide to elongate the building on the east-west axis, and have a shorter northern wall. Many people now however are experimenting with different shapes and sizes of buildings, so don’t be afraid to be creative (providing the design is sound.)
With a smaller northern side (whether shorter, narrower, whatever) the building will have less exposed surface area on the northern (non sun-gaining) side. This translates into lower heat loss. Combine this with a minimum of doors and windows on the north side, and lots of insulation, and your solar home is starting to be a twinkle in your eye. Don’t get ahead of yourself though, there is a lot more work to be done still even just in the design phase.
Ideally, you are going to want to find a spot for your building that has the minimum number of objects possible obstructing the sun’s rays. And by the minimum, I mean none. There should be no obstructions between 9am and 3pm solar time, in the winter. This is important. I have even changed the planned “exact location” of the cabin a few times just to avoid having to cut down too many/any trees.
You will want to go to the site with a “sun chart” which will help you to determine the position of the sun in the sky at any point in the day. The sun chart will help you to determine if there is going to be anything in the way (accurately, rather than just guessing) of your building’s south side.
On the interior of the building, you will want to pay attention to the orientation as well. Areas that are occupied more often should be on the south side of the building, and areas needing less heat like laundry rooms, closets, storage rooms should be on the northern side. These are often called “buffer spaces” as they help to shield the southern sun-heated living area from heat loss.
After making sure the area is free of obstructions, and laying out the interior of the building, you will want to lay out the building using stakes and string or surveyor’s tape, in its actual location, so that you can get an idea of how the building will look in the surroundings, and verify everything with dimensions.
With respect to entry doors, always give yourself a “mudroom” or “airlock.” By this I mean one exterior door that lets the person entering into a small room where another door needs to be opened to enter the building. This prevents large amounts of heat loss from the interior of the building by having the outermost door closed before opening the innermost door. If this were not implemented, cold air from the outdoors would be exchanged with warm inside air every time the door was opened.
As you may notice, many elements of Solar Heating Design are things that could be, and in many cases are, implemented on other homes as well. Preventing heat loss in the winter time for example, is an excellent way to reduce energy loss. Many people add weatherstripping and insulate doors and windows during the winter in existing homes, as it is, and many homes already have dual entry doors and windows on the south side.
Unfortunately many homes that are built already seem to have been built by someone who had no regard for the power of the sun whatsoever, and very well may be a lost cause if your intention is a mostly solar heated building. The best bet is to start fresh (although that is a hard fact to swallow with the price of building materials.. Try to recycle things if possible.. Tear down an old garage or barn for example, and use the lumber in the construction of your new structure.)
When starting from scratch, you will need to learn about many different aspects of construction, and in most people’s cases, deal with a contractor or several. Foundations need to be laid, frames must be built, and most importantly, codes must be followed. If you are going to be doing this yourself please get a few books on the subject, as well as copies of the building and electrical code, and make sure you study up before going to work.
That is all for now, but make sure to come back for my ramblings on window sizing, insulation, roof design, foundation types, thermal mass, and many other topics. The next step in designing our solar heated structure is deciding how the building will be constructed. By this I mean the foundation type, frame, wall, and roof type all need to be determined. I will go over some of the advantages and disadvantages of many of these construction styles with regards to solar heating, in the next section of this guide.
“Calif. billboard lights message with solar power”
On December 06, 2007 in Uncategorized
From xinhuanet.com:
“BEIJING, Dec. 5 (Xinhuanet) — Following in the footsteps of billboards in Canada and Africa, a California electricity provider says it installed America’s first solar-powered billboard that makes more electricity than it uses.
The billboard — topped off with 20 solar panels — is located at 1000 Brannan St. in San Francisco, and is visible from the Highway 101 9th Street exit.
”The energy that is collected by the solar panels actually exceeds the amount used by it on a day-to-day basis,” said Pacific Gas and Electric (PG&E) spokesperson Jennifer Zelwer of the standard-sized billboard, which proclaims: “This isn’t a billboard. It’s a power plant.”
On sunny days, the sign converts sunlight into about 3.4 kilowatts of energy, which is almost enough to power the household of an average U.S. family of four during the day. Zelwer said the billboard generates about 2.5 kilowatts of energy during cloudy days.
Although the billboard does borrow electricity at night, she said it has other green-technology tricks up its sleeves to keep the ratio of energy produced to energy consumed in the positive, including diode lights that use less than a third of the energy needed by standard halophane lights.
PG&E’s new solar-powered billboard isn’t the first in the world, as both Canada and Africa already have them. But Zelwer said it is the first in the Americas to actually push power onto an electrical grid, like ones in Africa do.”
