Another thread on solar panels

[chrisr]

we are looking at upgrading a couple of our solar panels, and thinking about these (monocrystalline) ;

SPECIFICATION:

Solar Cell Siemens
Grade Grade A
Max. wattage 200W
Max. power voltage 20.6V
Max. power current 9.25A
Open circuit voltage 22.66V
Short circuit current 9.6A
Weight 8.0kg
Junction Box IP65 Rated
Dimension 1020x 670 x 35mm

do these spex look right ? the size seems wrong for 200w ? is the seller assuming an unreasonable efficiency level to achieve this output ?

thoughts appreciated !

cheers,

[Off Trail]

Yeah, something seems off. The electrical specs match for a typical 200w panel but not the size; that's only 2/3 the area of my year-old 200w monocrystalline panels. So you're talking a huge efficiency gain not just a few percent.

Dan

[Mr B]

These are supposedly 250 watt panels,
Same size as yours,
Came off ebay, Melbourne company,
Been in business many years that I know of,

No one has challenged these ratings in reviews,

Cheers Brian,

[chrisr]

Originally Posted by Mr B

These are supposedly 250 watt panels,
Same size as yours,
Came off ebay, Melbourne company,
Been in business many years that I know of,

No one has challenged these ratings in reviews,

Cheers Brian,

thanks

are you happy with the panels ? have you actually measured the output ?

my concern is the 200w panels are 3.47m2 / 1000w. the 250w panel you mention is 4.01m2 / 1000w. most panels i've checked seem to be abt 5m2 / 1000w

this is abt 20-30% improvement in efficiency which seems unlikely ??

cheers,

[noelex 77]

Originally Posted by chrisr

do these spex look right ? the size seems wrong for 200w ? is the seller assuming an unreasonable efficiency level to achieve this output ?

Your suspicions are well founded.

The first anomaly is that the actual power rating from the specifications (vmp x Imp) calculates to 191w not 200w.

The second anomaly is even to achieve 191w, the efficiency for this sized panel would need to be 27.9%. If we use the rated 200w it is 29.3%. This is not believable. The best commercial panels have an efficiency of around 22% (for example the premium Sunpower X series has achieved 22.6%).