Must solar cells be UL certified

 Hi,

Does anyone know if there are any required certifications required to
manufacture and sell solar cells?  It's my understanding that any
electrical device that connects *directly* to the USA power grid must
be UL certified, such as Inverters, but the solar cells are not
connected directly to the grid. The solar cell would be connected to
an inverter.

I've seen solar panel *packages* for sale that say "UL certified," but
is that only because of the inverter?

Just want to be certain. Perhaps there are other certifications
required to manufacture and sell solar cells in the USA.

Thanks for any help,
Paul

  wrote:


The certification is at the photovoltaic (PV) module level. A PV
module is an assembly of solar cells with front/back covers,
encapsulants, frames, etc. as needed to pass the certification tests.

In The USA the primary certification is testing/listing to UL Standard
1703.  There are similar international standards.

The certification is not the only a fixed deal.  The manufacturer
specifies a maximum system voltage on the label, generally 600 volts
dc.  The testing voltages are higher and based on the vabel maximum
voltage.  

Most of the grid connected inverters sold these days in the USA are
rated to have PV array open circuit voltages up to 600vdc.  Most
inverter manufacturers provide a selection tool on the web for
selecting the range of number of series modules that can be used based
on site temperatures.

In many US states there are laws and rebate programs that require the
use of UL listed PV modules either directly or because the adoption of
electrical codes requires the use of Listed components (inverters,
wire, conduit, modules, etc.).

If it were your home, would you accept having a non-listed PV module
in an array such that the voltage to ground at that module could be
500-600 volts and the insulation or other parts could fail?

Low voltage PV modules in 12-volt systems are a different situation.

 
On Mar 5, 5:42 am, Ecnerwal

Thanks Bill and Ecnerwal for the very helpful info. So if the solar
cell DC voltage was less, say 12V DC, then it might not require any
certifications? And does amperage matter because I'm thinking in terms
of large packages, 500 to 5000 watts.

If even 12V solar cells requires some certifications, then what's the
absolute minimum cost to get 12V solar cells certified enough for
manufacturing and sales?

Any helpful advice to reduce the costs of certification is greatly
appreciated! It appears Green is now officially in, especially with
the new Obama focus on Green technology & jobs. Surely a lot of people
would like to enter into this field who don't have a lot of money such
as myself.

Regards,
Paul

 wrote:


The US National Electrical Code (NEC) basically requires using listed
PV modules.  This may not apply to vehicles and other applications,
but does apply to most buildings.

UL listed PV modules have 600V label ratings because once they leave
the factory there is little control on how they are installed.

High wattage at low voltage requires very expensive wiring.  5000
watts at 12 volts is 417 amps.  There are procedures to be followed in
selecting the required wire size.  For short distances a 700 mcm (US
size) wire is needed (see Chapter 3 of the US National Electrical
Code).  This is just under 1 inch in diameter.  Rather impractical.

If the 5000 watts is instead at 300 volts (typical actual operating
voltage), then a low cost #14 wire can be used (about 0.064 inches in
diameter),  1/170 th the area and cost.

Figure out how to use the standard products, they are that way for a
reason.

 
Here's why you want listed panels, in a nutshell (unlisted panels
self-ignited and burned to a crisp - house fortunately not burned
because the neighbors noticed the fire and called the fire department):

http://www.wind-sun.com/ForumVB/showthread.php?tE24

There are some interesting pictures in that thread. Especially this one.

http://www.fogbound.net/tmp/panel/IMG_1441s.jpg

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