Cheap Solar panel experience

[johnlm]

Ive not had much experience with solar (PV) panels so I have questions regarding the following experience.  I bought a couple of 5W Ammorophorus silicon panels from Harbor Frieght several months ago.  I wired them in parallel (they claim to have internal blocking diodes) to provide a trickle charge to my camp trailer battery parked up at some mountain property.  When I first got the panels I ran a quick check on them to see if they actually put out the specified power.  They were rated at 22V open ckt, and 450 mA short ckt.  They produced 22V ok  but the max short ckt current I could get was around 350mA.  I just assumed they were seconds short on current thus being sold by harbor.  After one summer of use the max short ckt current on the panels is now down to around 180 mA. The open ckt Voltage is still 22V. Both panels dropped in output current.  Any ideas as to what the issue is, or are they just cheap prematurely wearing out panels?  By cheap I mean they were $40 for each panel which in this size is on the low cost end.  Manufactured by some Chineese supplier I could not find much info on.  Any thoughts?

Johnlm

[commanda]

I have one thought. Is the glass clean.

2nd thought. Is this testing at the same time of year? That is, is the sun at the same angle to the horizon?

Amanda

[richhagen]

I recall reading that the initial output on the amorphous type panels is typically about 10% higher than you end up with over the long haul.  Your drop is in excess of that however.  I've seen these panels where the backside was not protected against the weather resulting in damage to the material deposited on the backside of the glass.  Just ideas, don't know about your specific case.  Some of the first panels I bought were these type panels.  I bought some off E-bay un-framed and also purchased an ICP 15Watt panel.  All suffered damage in the first year of exposure to weather.  With the exception of the ICP panel, I took them down meaning to coat the backside with something to protect them, and they still wait on my long list of things to do.  The only panel of similar type (although no glass is used) that I have which didn't show visible damage (although I have not tested the output in the last year and a half or so) is a uni-solar US-5, still up and working, however, those type panels are much more costly per watt.  Rich Hagen

[johnlm]

Thanks for the inputs.  I am testing the panels in the same manner as before with it directly facing normal to the sun.  The glass is clean (I've taken them down to do this testing).  The panels came ready to mount in an open weather environment so I did not do anything special to protect the back side.  Im still guessing that they were some kind of process defect in which they age about 10X faster than Amorophorus silicon is supposed to age.  I did have an ampmeter between the panels and the camper battery which I checked everytime I was at the site and as I recall the output current was never above 400 mA with both in parallel, so possibly most of the dropoff occurred soon after putting the panels up.  Im not sure if there is any issue with connecting panels in parallel if there really was no blocking diode in the panel as advertised.

[ghurd]

Bigger is cheaper. Dollars per amp. Dollars per year.

Amophorus silicon is the cheapest to buy.

They need much circulation all around them or they will over heat, reducing output greatly.

Are they yellowish? Heat damage.

Call and bitch. HF may refund the money better spent on a better PV panel from somewhere else.  Or at least replace them with crystalline (single/mono or multi) panels

[E man]

Just a thought, but you may want to check the output current of each panel separately.  You may have only one bad egg in the bunch that's bringing the other down when you wire them in parallel.

You mentioned a possible "manufacturing defect" could be the cause of the current drop...I was shopping for a cheap 50 watt panel a month ago, and got an earful of good advice from a local PV distributor.  One of the interesting things I learned was that  the major cause of panel [power] degradation comes from the middle sandwich layer between the glass and silicon; it's termed the encapsulent and acts as a clear cushioning layer.  Ethylene vinyl acetate I think is the stuff.  Apparently it degrades slowly under UV exposure and pretty much determines the productive lifespan of a solar panel.  

E-man        

 

[richhagen]

Now days, I look for panels that came, or come with a 20 - 25 year warranty, covered with tempered glass.  I've not experienced problems these type panels, I have panels from Arco, Shell/Siemens, and Photowatt, some I bought used.  I don't use trackers or any unnecessary mechanical stuff to break.  I use seal-tight and metal conduit (required in my area) to the junction boxes and hope to sit back and reap the power from them for years to come.  Just set them and forget about them (until you have to fix the roof).  Rich Hagen

[troy]

Yes,

All amorphous panels suffer a drop the first year.  Yours seems like a big drop.  The good news is that they don't drop much after that.  But for long term durability, either monocrystaline or polycrystaline panels will far outperform amorphous for decades and decades.

The other thing to keep in mind is that rated output for ALL solar panels is under ideal conditions.  That means a totally cloudless hazeless sky, sun at solar noon, sun high in the sky, and very cold conditions.  As soon as the panel gets hot, output can drop 25% or more compared to rated.  Really, they generate panel ratings in the lab with artificial "perfect" conditions.  So you may never get rated output even from a monocrystaline panel.

Good luck and have fun!

troy

[ghurd]

Could be the current rating was for 'New' (it drops like a rock the first 6 weeks).

Most brands list the broken-in current, not the 'New' current. I've seen this burn up controllers when a system was too tight on the tolerances.

With rule of thumb numbers...

5w / 17v = .294a

So they are kind of on track for the watts, they just used 2 sets of numbers on the box.

Don't let them get hot and they will last a lot longer. Give them some air space underneath, at least 4".

They, HF, did the same thing to me by not listing watts or dimentions, and having the decimal point off one place. I'm the proud owner of a $31, 0.6w plastic panel.

G-

[troy]

Hey, come on...

That's only $51.67 per watt.  Hmmm, four bucks a watt is the going price for good large monocrystaline panels in bulk, so you've only paid:

51.67/4= 12.9x the going rate.

My condolences...

troy

[ghurd]

I did the $ math on sending it back. Then I kept it. One of those catch 22s.

Well at least its mono. About 3x5". The plastic frame is OK. Impressive output for the size. Made in Russia, by hand I think (cells not set square, solder not uniform).

Used it for charging AA's once, works nice for that. It will probably go fishing with us in Northern Quebec, but I already have enough mini panels for that.

(Fishing solar charger- Takes the space of about 6 CDs in regular cases. 3 @ 12v, 150ma each, mounted on fiberglass backing. 2 'controllers' with regulated outputs for 2, 4, 6, or 8 AA's, and 2 different camcorder batteries. Lots of 'adapters'. From 1 to all 3 panels can be used for different batteries at the same time. Whole thing cost about $60. Whish I could get more of those panels for the same cost.

Nobody will touch it but me. Looks like its dangerous. They won't even re aim the panels toward the sun!)

The HF panel IS kind of nice for what it is. Just seems more like $10 would have been a little more fair.

I'll see if I can find the HF part number, just in case some one wants to cover their roof with them...

G-

[ghurd]

Was at their retail store today. No Name, 5W, $40 (on sale), amorph, listed as 350mA. Kind of a bright box (yellow and white mostly?) 450mA must have been the 'New' output, before burn-in.

[juiced]

Hi G.

   If you are in the montreal area, and are interested in doing some projects, let me know. I could use some exp.

           I have a site up, it has some technical info (lots of pics) on panels and everything else... (im working on the practical knowledge now.) Check my sig.