Solar panel brands???

[Gresford]

I'm new to photovoltaics so I may not be wording this question correctly but I'm hoping that someone can help me.  I am looking to purchase solar panels to add an array to my off grid generator system.  Are there certain brands or types of solar panels that are more efficient than others? By efficiency I mean the ability to collect the sunlight for the most hours during the day regardless of the angle of the sun for battery charging and the quality of the panel itself.

Thanks,

Gresford Thomas

[Titantornado]

Not so much the brands, but the types, yes.  Monocrystalline and polycrystalline panels are more efficient than thin-film, flexible, or amorphous panels.  Monos and polys cost a bit more, but will also have a much longer service life.  I've heard (but since I never had any, I can't confirm) that thin-film panels loose a lot of their output pretty early on, then settle down to operate at a lower value for the rest of their lives.

What you really want to look for is the comparison between the rated power and the minimum (guaranteed) power.  Some have a difference as low as 5%, others (like the ones I have) are 10%, sometimes higher.  (I got mine because the price was too good to pass on)

What really makes solar panels worth their grit, is the charge controller.  An MPPT (maximum power point tracking) controller will squeeze every bit of available energy from the panels under all conditions.  A solar tracker can also capture a lot of additional watts every day that would have been lost to fixed panels.  I guess what I'm getting at is, it's not only the panels that makes the system efficient.

[disaray1]

 Yes, photovoltaics come in a variety of flavors. MONOcrystalline tend to be the most efficient, followed by POLYcrystalline, and Amorphous (Thin Film) comes in last. I won't talk about brands. Google "solar panel", and you'll find more info, and lots of sellers that usually have spec sheets (with efficiency) on the brands they sell, so you can compare them for yourself.

 If you like to build stuff, consider building your own. There are a number of manufacturers producing individual cells perfect for DIY.

  David

 PS. The "good" stuff that the aeronautic/space agencies use are generally available to the public...double juction and triple junction cells (with efficiency ratings at almost 30%!) are the current , on the shelf tech, with quad junction not too far away...

[12volt dan]

Don't worry too much about efficiency Gresford, the efficency of a panel affects the size of the panel, that's about it. Cost per watt (unless space is at a premium) is the first thing your worried about,that and warranty.

 Most decent brands are giving a 20-25 year warranty. That would suggest to me that that panel is reliable.

Disarray

 30% efficient? can you point me to a site? and  whats the cost?

 The faster the technology advances the cheeper it's going to get :^)

[Clifford]

Look up:

Emcore, Boeing, Spectrolab for the high efficiency triple junction cells.

http://www.emcore.com/product/photovoltaic.php

http://www.spectrolab.com/

They aren't really selling them for "home" use.  The main difference between the standrard 10%-15% cells and the double and triple junction cells 20-40% efficiency is the panel size.  

Get the cheaper silicone cells if you have enough space.  If you don't have enough space, then economize.

The double/triple junction cells would be useful if you are investing in some kind of a solar tracking mirrored (or magnified) array, or if you are severely limited in space, for example on an electric car.

[tornado6]

If you are looking for manufacturers,id say Evergreen or Sunpower.Top of the line and high efficiency but first poster was absolutely correct,the batteries,controller,line length and position all determine final output.
Start small with maybe one,two panels and work your way up.Youll find over time you will get addicted to seeing your energy expeditures go down after having a base system in place.

[craig110]

I have Kaneka thin-film panels and yes, they do generate less power after their break-in period is done.  (The data on the panel says that the wattage can be as much as 30% higher during the first six weeks.)  There are two ways of looking at this, however.  The first is to object to the panel dropping to its rated output after the break-in period is done, and the second, which I prefer, is to buy it for its rated output and be happy getting some gift power during the break-in period.

Now, of course, this does mean having to design the thin-film setup so that the rest of the components can handle the initially higher voltage and amperage.  I wouldn't have gone with thin-film if I was cutting the design so close that it couldn't handle more power for a while.  For example, connecting 700 rated watts (ie. post-break-in) of thin-film panels into a 60A 12v MPPT controller, which can handle 720 watts, would be problematic during the break-in period.

Craig

[DanG]

With 40 pounds of loose PV cells incubating in basement I've decided what you are really paying for is the warranty - I can't make a array that will last 3 years let alone 30. Here is a re-print of a post I made a while back...

------------------------------------------------

Some inspired-lawyer writings for y'all to muse...

Shell Solar: 2-year limited warranty on material & workmanship, peak power warranty of 90% at 10 and 80% at 25 years. Transferrable warranty.

http://www-static.shell.com/static/shellsolar/downloads/products/warranty_us.pdf

Sharp Solar: 1-year limited warranty on material & workmanship, power warranty same as above. Warranty transferable if modules convey with property.

http://solar.sharpusa.com/files/sol_dow_Module_war.pdf

Kyocera Solar: 1-year material or workmanship, 12-year 90% power, 80% to 25-years.

Warranty non-transferable.

http://www.kyocerasolar.com/pdf/specsheets/kc_warranty.pdf

BP Solar: 1 to 5-year material or workmanship; 10 or 12-year 90% power, 80% to 25-years. Warranty transferable if modules convey with property.

http://tinyurl.com/df54b

Schot Solar: 1-year material or workmanship, 10-year 90%, 20-year 80%.

http://tinyurl.com/8bnx6

(http://www.fieldlines.com/story/2005/4/26/175836/155)

[Gresford]

Thanks everyone.  It looks like there is quite a bit to take into consideration.  I will research each of your suggestions and plan accordingly.

Thanks again!

Gresford

[disaray1]

Sorry Dan, I was sleeping again and Clifford beat me to the punch..and spectrolab (Boeing) was where I was looking..also ck out the new concentrator cells!  Only $5k for 20 cells! What a deal!. Now all I have to do is get a couple-o-more fulltime jobs to afford some!

 Sleepin' Dave

[12volt dan]

no problem, I can allways dream of a 30% 2 dollar cell :^)

 Only 5K? wow. I'll remortgage tomorrow :^D

[tornado6]

Yeah just wouldnt subsidize shell or BP.On an interesting note it seems that the oil companies are divesting their solar interests and getting out of the solar game.Financially with all their production plant selloffs thats what seems to be happening as Shell now only has a small production cap. in Si thin films and BP sales have been flat.BP is now the only oil company that produces point to point solar panels.What will that mean in the future?   : )  2$ 30% cells.

BP and the others were really into the R & D advancement aspects of solar-they have been around for a long time but why is it that smaller startups are the ones who come up with the true advancements in PV technology and silicon processing?

The answer is simple but just wanted to say that with the boom that is going on now--it will create massive price drops when everyone streamlines their manufacturing processes.2008-9-10 you will start to see panels at walmart prices.Right now,its all about the silicon processing capacity shortage.

[12volt dan]

Yup a lot of companies are getting into silicon production with plants opening in the next few years and many more into solar panels

 I'm ready for those cheep, mass produced ones myself :^)