Visit to Shenzhen, China

[David HK]

In the middle of May I shall be making a trip over the border (Hong Kong to Shenzhen) to visit a factory producing solar panels.

The web site address for one company is:-

http://www.solarlight.cn/en/overview.php

Perhaps some of you clever gentlemen could take time to go through the site and examine some of the data they print for the capabilities of the solar panels they produce.

I would like to be reasonably intelligent with my questioning and I would much appreciate any caveats, cautions or other points to look for when discussing the 'claimed' outputs of all the panels they produce.

Any other tips would be much appreciated.

Regards,

Dave HK

[ghurd]

Hi Dave,

The ratings they show are to industry standards. A very good sign.

The polycrystalline silicon is a good choice.

The 18 cells per 12V nominal series string is good.

The photo shown is very much like some panels I own. Very much!  I would guess they are the same panel. The label on mine has different model designations. Same 2 year quality guarantee.

For the ones I have, they are better than the ratings on the rear label in open volts, short circuit current, and peak power watts.

However, the importer on my panels under-rated the label watt rating by 20%.

Maybe the importer knew something I do not, but I am pleased with mine.

Possibly ask to test one or 2 panels outside in the sun. Check open circuit voltage and short circuit amps. They should be close to the label ratings in good sun at noon.  I do not believe it is needed to test into a battery.

Look at the cells in a panel to see if they are straight and even. Cells with corners very close to other cells would concern me.

Look at the solder joints on the cells. They should be level and shiny, not lumpy and dark grey.

Hope something helps.

G-

[ghurd]

"The 18 cells per 12V nominal series string is good."

Make that 36 cells.

G-

[David HK]

Hello Ghurd,

That is exactly what I need. Well done. I will write up a short report for the board when the trip has been completed.

Regards,

Dave HK

[David HK]

Something I overlooked.

I know how to check open circuit voltage, but what is the procedure for testing short circuit amps?

Dave HK

[ghurd]

Set the meter to DC amps, at a higher than expected position. One meter lead to each solar panel wire.

[wpowokal]

Remembering most multimetres, that the majority of us would be using I suspect, can stand high current only briefly.

allan

[Clifford]

You must be planning a big project if you are actually visiting the factory.  

Either that, or you are going into selling them.

I wonder if you could get a better estimate of power by pushing into 4 rechargeable NICADS???  You could probably even get some kind of a reading using AA batts...  although, of course, you don't want them to be fully charged.

Here are some random ideas that have popped into my head.

• Screening Process.
  
• Bonding of metal to the cells
  
• Tempered Glass
  
• Plastic Covering rather than Glass
  
• Bonding method between cells and bonding to the wiring.
  
• Anti reflective coatings / surface
  
• Weather proofing.
  
• Warranty
  
• How they anticipate servicing the warranty
  
• What does the warranty cover?  Failure?  Low Volts? Low Amps?  Breakage?
  
• I wonder if there is a rating of voltage / power drop over time.  
  
• I would certainly ask to see the oldest panels they have and try to get an idea of what has changed with the panels over time (power loss) as well as what is different with "today's" panels.
  
• This is China...  might as well ask about QA/QC...  Do they match cells for color?  Do they match cells for power?  Reliability? Failure Rate?  Durrability?
  
• Is there a UL Listing for Solar Panels?
  
• Frames and mounts?  Will competitor's frames and mounts work?
  
• What environmental conditions are important based on the ultimate destination of the panels?  Hurricanes?  Tornados?  Hail?  Here in the Midwest...  I'm terrified of the idea that my panels will be pelted by golf-ball or tennis ball sized hail.
  
• Are you comfortable with the power junction boxes?
  
• HEAT dissipation / performance / resistance.
  
• Solar Tracking
  
• Do they have their own Research and Development Department?
  
  

Oh....  another thing that you might look at.

There was one company that was putting holes in their solar cells to allow light through.  For example, you could use them over skylights to allow in some ambient light.  I think there were other companies working on more transparent/translucent technology.

In this case, you might also ask about build-to-suit panels.

Thinking of my Siemens panels...  I just never seem to get as much juice pushed into the cells as I think I should.  I'm going to have to do a little more testing...  but I've wondered if the epoxy that Siemens used wasn't as stable as it should have been...  and I've lost some of the electrical connection.

I'm working on building my own panel now... and then I'll at least have something to compare them with.

Most of all... have fun, and a wonderful trip.