Seriously, would you trust a Harbor Freight solar cell? I don't buy anything from that store that needs to plug into the mains.
---------- George W. Bush had an honorable discharge and proved to be the dumbest f*ck ever to hold a political office. 'nuff said for your sig.
UNTIL Obama!
And no shipping if you buy them at a local store.
-- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.
That's your choice. Buy whatever turns your crank. I have several power tools I bought there, and they do exactly what I bought them to do. Several work better than the Craftsman crap they replaced. They should change their name to Crapsman.
-- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.
Suit yourself! I am happy to have a Harbor Freight near me, but I recognize that they sell mostly crap. Fortunately; for light duty and occasional use, crap is sometimes good enough.
I have seen their PV panels and decided to taka a pass in favor of a much better quality panel.
Vaughn
better
Taka all the passes you want. I've bought tools from them for decades. I've had one bad tool out of hundreds. OTOH, I know crap tools when I see them. The imported Japanese tools I saw in the '70s weren't worth taking out of the plastic bags they were shipped in, yet some people had tool boxes full of them. They were both poorly made and dangerous to use.
-- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.
It appears to me that Philadelphia gets year-round-average insolation of 175 watts, at least 170 per square meter. Compare that to the 1 KW per square meter that I have some impression that solar cell arrays are rated at...
That sounds to me like 34-47 dollars per watt in Philadelphia, if the panels are laid horizontally.
I am guesstimating that by making them facing 40 degrees south of zenith (towards "high noon" sun on days of the equinoxes), an improvement of 40% of the 30.5% high-noon-equinox improvement would be achieved on year-round-average. Maybe tilt them to face 37-38 degrees south of zenith because the sun is up and out more in the spring and summer than in the fall and winter. Maybe tilt them to face 2-3 degrees north of the celestial equator and 7.5 degrees east of "high noon meridian" to take advantage of the fact that on average during daytime there are more clouds after noon than before. (I am aware of "morning fog / foggy low cloud" exceptions to this "general rule"). At this rate, I expect about a 15% improvement by optimizing how the solar panels are aimed. Without further optimization to motorize them and get them to track the sun.
So, I see good opportunity of a Philadelphian to get the cost down to $29.50-$41 per watt.
Considering that a Philadelphian pays nowadays about 14.5 cents per KWH of electricity at "residential rate", excluding the surcharge for consumption past 750 KWH (I hope I got that right, too lazy at this moment to dig out a recent electric bill) per month during a defined air conditioning season.
At this rate, even a Philadelphian who wears nice cool summer dresses in the house and uses fans rather than air conditioners and tolerates subtropical to often-worse-hot weather well and frets more about winter than summer and who lives in a rowhouse (good for stealing some climate control from any more-climate-control-needy next-door neighbors) would have a $29.50-41-per-watt solar panel paying for itself in 41 / .000145 hours, which works out to...
About 23-32 years, assuming inflation in electricity cost is the same as inflation of cost of cost of whatever else a homemaker has to pay. If one does all maintenance required and in the likely event the solar panel and the likely-associated DC-AC inverter (at maybe 90% efficiency) keeps on truckin', then it's 25-35 years to pay for itself, and 50-100 years to double the invested money. ===== Suppose sun tracking with at least one motor is deployed, at consumption of 5% of the output of the solar panel. At that rate, I have liking for:
Philadelphia above atmosphere year-round-average appears to me to achieve about 315-320 watts per square meter of insolation, while at ground level appears to me to achieve 170-175 watts per square meter. That makes me think "at this rate" that 1 KW per square meter of direct sunlight is degraded to 530-555 watts per square meter of a solar panel that tracks the sun, before loss from electrical power consumption of devices to track the sun and before correction for maybe 40% of the time there is significant cloud cover that at least mostly destroys optimization of sun-tracking (as a "representative figure").
At this rate, I have a liking for 95% of 60% of the way from 175 to 320 watts per square meter to be divided by 175 watts per square meter... 42% improvement of rate of return, down to 70.3% as much time to get money back to you - as in about 16-22.5 years to pay for itself, or about
32-45 years to double your money should you have no expense at maintaining the system that long. (If the system requires rechargeable batteries, plan on additional expense because such bateries have a high rate of expiring in less than 32 or even 16 years.)If you double your inflation-adjusted money in 16.6667 years, then the annual rate of return is 3% above the effectively-actual inflation rate.
I seem to think that the total rate of returns of major stock index funds, especially "total stock market" ones, have done better from 1970 to now or would have if they were in operation according to their stated rules should they have been in existence in 1970 - I would guess likely even in UK, let alone USA! For that matter, fair chance even from the roughly-1970 high to the 2009 low! (second-worst 39 years of USA stock market - behind the 39 year stretch starting at or a bit before the 1929 high. I seem to think that stretch had USA total stock market outpacing "official inflation" by 4-5% with reinvestment of dividends, minus the ~.3% annual expense ratio that a good index fund like Vanguard "Index Total" should have and that Vanguard achieves.)
-- - Don Klipstein (don@misty.com)
Where'd you get that impression? Here's a typical module.
GIGO
Wayne
Only arguably for one specific office of one of 2-3 brances and
3-to-often-4 levels of government where both level and branch exists and where the office in question is one voted into by voters.I seem to think that Philadelphia has elected some mayors that would make the bumber of the 2 bushes look like an outright brainiac in comparison. I even remember one November election between two that some called "airhead vs. vacuum", and occaisionally as the one to choose which of the two worst prior mayors of Philadelphia to put back into that office.
Let alone elections for the 17 councilcritters (unicameral legislative branch) for Philadelphia... Where 10 are elected from districts, and 7 are elected "at-large" (on citywide basis as opposed to representing a district of the city), with Philly's city charter having an "affirmative action program" to limit to 5 of these 7 being in the same political party. Post-1949, Philadelphia has usually had 14-15 Democrats and 2-3 Republicans in their legislative branch of gubmint.
And it appears to me that most Philadelphia councilcritters leave office by dying in office, retiring at a very old age, need to go to prison, or due to racial change of a district that they have to be re-elected from. And when the councilcritters worse than the mayor mismanage the government of the city (despite a "strong mayor" city charter), their constituents tend to blame the mayor.
=========
From before Civil War to sometime around or a bit before 1950, the contentedly corrupted Philadelphians tended to employ stinky awful Republican mayors. Then, they elected a good Democrat mayor, followed by a fairly/somewhat good Democrat mayor, and after that to now sent to City Hall Democrat mayors that wre/are at best were so-so (in my opinion) and at worst (in my opinion) stank even more than the worst Republican mayor that Philadelphia ever endured.
I seem to think that Philadelphians often elect and re-elect local government officers worse than every President that USA ever had.
-- - Don Klipstein (don@misty.com)
My experience in and near Philadelphia is that school days are centered around noon or less than an hour before noon.
Keep in mind that on average, cloudiness is worse after noon than before even in Philadelphia with their few days per year clouded by "morning fog" or "morning foggy low clouds".
-- - Don Klipstein (don@misty.com)
On which point?
The folks showing up at the health care town-halls were bussed in and were misrepresenting themselves. There was video of the buses and several cases where they followed up and proved that they were in fact party operatives.
People may be angery at the government for spending too much but very few are willing to have the spending on their pet things reduced.
Huh?
Absolute *CHECK* !!
Probably from reading the specs and knowing about the typical efficiency of PV cells. The output rating of PV cells is usually quoted under "full sun" conditions of around 1000 W per sq. metre.
That's the electrical output of that panel, which given the normal efficiency of panels like that (10-15%) means an insolation of around 1000 W per sq. meter. Actually the specs for that panel claim 13.1% efficiency so slightly over 1000 W per sq. metre is required to achieve that output.
Not so - those were pretty accurate calculations.
Of course if you want efficient use of solar energy then solar thermal is the way to go - it's not too hard to get 70-80% of the insolation energy available as usable heat.
-- Steve O'Hara-Smith | Directable Mirror Arrays C:>WIN | A better way to focus the sun The computer obeys and wins. | licences available see You lose and Bill collects. | http://www.sohara.org/
The "economies of scale" aren't just the simple stuff, such as when you ship 100,000 units a year it becomes worth your while to put most of the electronics into an ASIC. It covers the sort of developments where people think that the market is big enough to justify developing a completely different way of making solar cells.
This sort of development is highly speculative and costs tens to hundreds of millions of dollars by the time you've turned it into a production line - nobody invests that kind of money until they are pretty confident about the eventual market.
Economists don't understand any of the technical details - they just know that as the market for a product expands, the unit cost tends to halve for every ten-fold expansion in production volume.
The first computer I ever worked with hands-on was a PDP-8. It cost something like ten times what I was being paid per year at the time. Nowadays there are single chip processors that are moe powerful that sell for about what I'd earn in a minute if I could persuade someone to hime me. Solar panels need area in a way that processors don't, but they are going to get a lot cheaper to make and a lot easier to mount (perhaps as stick-on films).
-- Bill Sloman, Nijmegen
No kidding?
If Klipstein mounts one of the modules I referenced above in full sun in Philly on a cool day and measures the output, he'll conclude that it costs out at ~$2 per Watt, not the $30-$40 he managed to arrive at. To avoid starting with worst case PV costs he could google "best price PV". And he could skip even more GIGO by using HOMER or some such.
Wayne
That is their price per peak output per watt installed and seems unusually low. $4/W is still about the going rate and some are closer to $8/W where you paying a premium for higher efficiency.
But unless you can arrange continuous sunlight the average output over the year allowing for clouds and including diffuse light is something like 1/8 to 1/10 of peak installed capacity. So his $30-40/W delivered for use is basically in the right ballpark in the long term.
Operating at peak efficiency with a clear sky and normal incidence sunlight then the array can achieve peak performance, but the rest of the time it does not by a long way. And obviously at night it is idle.
I think you just have to be clear about what measure you are using.
The PV array link you pointed at is the cheapest I have seen on offer - has anyone here obtained one? Or are they vapourware?
Regards, Martin Brown
The string ribbon process mentioned appears to belong to Evergreen Solar, it looks to be a very clever process for producing silicon PV cells.
-- Steve O'Hara-Smith | Directable Mirror Arrays C:>WIN | A better way to focus the sun The computer obeys and wins. | licences available see You lose and Bill collects. | http://www.sohara.org/
Unfortunately the Earth does not constantly turn the same face against the sun.
In places close to th equator with only rare clouds (such as Sahara) with dual axis tracker, in principle the nominal power would be avaible 50 % of the time, thus the average cost would be $4/W. However, the air mass losses close to the horizon will limit the full power time to 8-10 hours a day, thus at least $5/W in ideal cases.
For fixed installations in ideal cases 1/4 of the peak power would be available on average (hence $8/W) .
For higher latitudes, the winter atmospheric losses will reduce the available power significantly, even with ideal orientation.
In many places, there are those pesky things called clouds ....
This will further reduce the annual energy output and hence increase the cost/W.
While 5 % may be a lot, but on the other hand, can you buy a system with a solar panel mounted on a dual tracker capable of surviving snow/ice/sand storm/hurricanes for $2/W (peak) ?
veral
I was in HF one day when a guy returned a reciprocating saw. It caught fire. Need I say more!
HF is a great place to buy a tarp, those stepped hole drill bits rock, and I use their plastic bins to organize components. But plug into the mains? I don't think so.
s n
der
Right... the store pays the shipping and passes the cost right on to the customer. :D
Michael D.
several
ey
Good point. For wrenches and such, HF seems good enough for light car maintenance work. But...
I bought a rechargeable drill from them awhile back, and the NiCd battery charger doesn't even have a sensor telling when charging is done. You have to guess when it's done charging.
Dad wanted to buy same drill (on sale for $15); I talked him out of it.
Michael
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.