Wednesday, October 31, 2007

A missed call

I generally don't give investment advice--and that is a good thing. There is one merger that I commented on last year (11 months ago anyway) between Sunpower and Powerlight. At the time Sunpower was trading around $40/sh and I felt that the merger was a defensive move to ensure a market channel for their panels in case the silicon shortage unwound rapidly. (Sunpower at the time was (I believe) the largest domestic module maker, but certainly a quickly growing force in supplying solar modules; Powerlight was perhaps the largest system installer in the US.)

Today the silicon shortage has yet to unwind, but we have seen a big change in the average size of panel installations. Whereas five years ago installations of 25-50 KW were notable, today it seems that installations have to be at least 500KW or more likely 1MW to get industry press attention. The combined Sunpower seems to be focused on this scale issue and seems to have gotten out in front by combining organizations. At the very least Wall Street continues to like the deal--the combined Sunpower is trading over $125 today. 3x in less than a year is a very good return in anyone's book.

Too bad that return doesn't figure into my book...

Friday, October 26, 2007

Some photos of the demo solar panel

I've been asked how the demo solar panel looks, and I know that people are always concerned with aesthetics, but it strikes me that beauty is in the eye of the beholder so I've decided to post a few additional pictures on the demo solar panel in my livining room.

These last two are how the panel looks from the cell side and the mirror side respectively.

Tuesday, October 23, 2007

More on the demo solar panel

I was somewhat unsatisfied with my measurements over the weekend (b/c of high variability), so I decided to measure the solar panels again today.

First of all I wanted to confirm that the 27% power increase was not a one time fluke, and secondly (perhaps because of my engineering background) I like to double check my measurements before making claims & assertions. The bottom line is that I measured between 26-30% increase in power with my solar panel design over the standard design.

It was a good sunny day although there were some small clouds that passed across the sun while I was taking measurements. I tried to wait for them to clear before making a reading, but I noticed some fluctuations in the current measurements (as a result I provide a range rather than a single number).

I got even higher readings for both panel's output (despite slight clouds, the day was cooler {weather service forecast 62F}). Solar panels should produce more power in cooler temperatures which may have contributed a bit. Also of interest on the topic of temperature the standard panel temperature was ~35C while the mirrored design read 45-50C when I took power measurements. Today was not as windy so I was able to do a better job setting up the panels so they faced toward the sun.

Standard panel
Voltage = 20.3V
Current = 2.4-2.6A
Power = 48.7-52.8W

My panel
Voltage = 5.11-5.3V*
Current = 11-13A

Max Power = 68.9W (13A x 5.3V)

*The voltage was steady each time I measured it, but I did get two different readings. My meter measures either current or voltage so I need to switch back and forth to take my readings.

If I use the 5.3V reading, power = 69W; the power increase is 30.5%...yes!

Even using the lower 5.11V reading shows a power increase of 25.8% from my panel.

This time I also brought my camera to document the set-up.
Here are the solar panels side by side, soaking up the sun. In case it is hard to tell, with my demo solar panel, the solar cells are roughly straight up and down and the mirrors are basically parallel to the ground. Both panels are set at roughly 45 degrees, although the panel with the mirrors may be at a slightly steeper angle.

I've included a snap shot of the current measurement of the mirror panel showing a high (12.98A) current reading. After nearly throwing away the 11.4A reading from Sunday (after having trouble getting it again, I was delighted to get much higher readings today).

Panels above and meter below.

Sunday, October 21, 2007

Demo Solar Panel Performance

We had a freakishly warm and sunny weekend (for late October) here in Chicago, which allowed me to put my solar panels (snap shots here) out in the sun.

Each solar panel is rated to produce approximately 36W (according to my supplier) and each panel has 36 cells, which means each 5" x 2.38" cell must produce roughly 1W.

The maximum theoretical power increase from my design is 40%. Since my acrylic mirrors only reflect 87.5% of the light that falls on them, the panel I'm testing will at most produce a ~31.3% power increase over a standard panel with the same number of cells (assuming everything else is ideal).

One additional note is that the the panels were wired slightly differently, in the standard panel the voltages from each strip of cells add up, in my panel the currents add up. This means that you really need to multiply the voltage x the current to get the power produced to compare the output from the two panels. (My solar panel supplier says this wiring difference was a mistake.)

The bottom line is my demo panel produced between 12%-27% more power than the standard design depending on orientation to the sun.

The first two tests I ran with the panels placed on a small step forming ~5-10 degree angle with the ground.

Standard design
Voltage = 19.4V
Current = 1.75A
Power = 34W

My design
Voltage = 5.0V
Current = 8.0A
Power = 40W

17.6% increase

Standard design
Voltage = 19.3V
Current = 1.99A
Power = 38.4W

My design
Voltage = 5.07V
Current = 8.47A
Power = 42.9W

11.7% increase

The good news is that my panels are clearly producing more power than the standard design, but I was somewhat disappointed that the increase was on average ~1/2 what I was hoping for.

I realised that I basically had the panels pointing straight up at the sky when the sun was clearly down in the sky. So I decided to run one more test with the panels pointed more directly at the sun.

Standard panel (at ~45 degree angle)
Voltage = 20.0V
Current = 2.3A
Power = 46W

My design (at ~50 degree angle)
Voltage = 5.13V
Current = 11-11.4A*
Power = 56.4 - 58.5W

22.6 - 27.1% power increase

*I clearly read values between 11.4-11.5A (w/ some slight fluctuation) but after a big gust of wind nearly knocked my panel over, I found my readings only reached 11A. I didn't think of it the time but following the gust the panel may not have been realigned properly, in any event I'm reporting both numbers. In both cases, it is clear that my design registers greater out performance when pointed directly at the sun.

Some people express concern that concentrating sunlight onto a solar panel may "overheat" the panel and impair performance. I added a thermo-chromic temperature strip to each panel which measures temperate in 5 deg.C steps between 25-100 deg C (77-212F). The temperature showed the panels at about 40C (104F) most of the time I looked at them(after several minutes of warm up time in the sun) . If the air became very still for several minutes I sometimes saw my design creep up to 45C (113F). The ambient temperature was in the 70s both days (the weather service predicted about 5 degF higher on Sunday than Saturday) although Sunday was much windier. A modest increase in cell operating temperature may occur using my design, especially if there is no wind.

Wednesday, October 17, 2007

There he goes again...

I can't believe how obnoxious it is for Bush to be talking about WW III, Iran and preventing them from having knowledge of how to make nuclear weapons all in the same breath. Holy escalating rhetoric Batman!

This is the president of the USA talking about Iran here, not the combined forces of China, India and Russia! I mean Cheney spouting off is one thing, but this rhetorical bombshell seems to very nearly be the purpose of the press conference.

While I understand the principle that we as a nation want other nations not to make nuclear weapons, I do think it is something else entirely to have as our stated goal to prevent knowledge of how to make nuclear weapons...not only is that horse out of the barn, it seems the horse died of old age 50-60 years ago.

But the other problem is that we know that the Bush administration sees things that don't exist (links between Saddam and Al Queda, Saddam's WMDs etc) and attribute motives to people we don't know (ala the only reason Saddam has WMD (and is seeking uranium) is to attack America).

Moreover since we refuse to speak to Iran even in diplomatic settings (I don't count Bush's belligerent "microphone diplomacy"--talk about the bully pulpit!), it really is not known to us what they know or don't know which in turn makes it precious difficult for us to police their knowledge.

All in all, I don't see how this advances US "interests" in the middle east.

Sunday, October 14, 2007

Solar Invention Demo

Since tomorrow is Blog Action Day, I think this is a perfect time to highlight one idea I've been working on to reduce the cost of solar panels.

Last year, I filed for a patent on a new way to make a solar panel. By building the panel differently, one can use fewer solar cells/watt of output.

This week I got some hardware that should help me demonstrate the idea.

Below are a several pictures of a demo panel I had made to show to panel makers (to convince them to license the idea) and/or investors. Some of the mirrors look foggy, because they have a protective coating (to reduce scratches during handling). These mirrors are made from an inexpensive acrylic, but are still fairly good mirrors. According to my patent, the cells and mirrors are built into the panel i.e. what you see in these pictures would have a protective glass cover just like normal panels you can buy and install on your roof today. My panel is bigger so it collects more sunlight, but it uses fewer solar cells than a standard panel. Mirrors cost 1/10 as much as solar cells, so the savings can quickly add up.

The first picture shows a standard panel (left) alongside my demo panel (right sans mirrors). The guy that built my panel didn't want to get involved with mirrors!

Both panels have the same number of cells, but my panel is larger...and hence will generate more power.

Below is an edge view of the panel with acrylic mirrors installed (mirrors are foggy from protective coating) on my kitchen table.

Below is a picture of yours truly pointing the camera toward the mirrored side of the panel. One sheet of mirror has protective coating removed to show that the mirror actually reflects!

Below is a close up along one of the mirror/cell pairings. The mirror is on the left and the row of cells is on the right.

Below is a view from a slightly steeper angle (same orientation).

Well there it is!

I haven't had a chance to put this in the sun and document how much more energy my panel produces compared to standard design, but hopefully I can do that soon. I expect about 25%-30% more power from my design.

Nobel Al Gore

Congrats to Al Gore (& the IPCC) on winning the Nobel prize. It seems that the good folks in Sweden have noticed a shift in the debate on Climate Change since "An Inconvenient Truth" came out, as I also noted in a recent post.

I really really wish one of the democratic candidates would put Global Warming in the top two or three categories they talk about. I think Obama in particular would get a big boost if he did, since this also fits his young supporter demographic. He has been running a rather conservative campaign in my opinion. OK if he simply wants a VP position, but not enough differentiation from Clinton if he wants to win the nomination himself. Proposing a modest but gradually increasing carbon tax would definitely set him apart from his challengers, and provide a second leg (aside from rolling back Bush's tax cuts) to fund any proposed spending initiatives (like health care).