60 Cell panel VMP

mcgivor

Looking for panels I came across some 250W 60 cell with the following specs.
 Manufacturer Zhunyan
 Polycrystalline 

P max                          250W
Voc                               43.2V
Isc                                 7.72A
Vmp                              36v
Imp                                6.95A
Sys V  1000V
Power Tollerance       +/- 3%

What stood out is the Vmp, from all the information I've researched, 60 cell panels are usually in the 30-30.4v range and are not recommended with PWM controllers, but with these? Could be those smaller Chinese volts, watts and amps like the legendary Powe Jack contraption uses, who knows  . Google comes up with nothing for Zhunyan. 

bill von novak

mcgivor said:

Looking for panels I came across some 250W 60 cell with the following specs.
 Manufacturer Zhunyan
 Polycrystalline 

P max                          250W
Voc                               43.2V
Isc                                 7.72A
Vmp                              36v
Imp                                6.95A
Sys V  1000V
Power Tollerance       +/- 3%

What stood out is the Vmp, from all the information I've researched, 60 cell panels are usually in the 30-30.4v range and are not recommended with PWM controllers, but with these? Could be those smaller Chinese volts, watts and amps like the legendary Powe Jack contraption uses, who knows  . Google comes up with nothing for Zhunyan. 

My first assumption would be that Zhunyan has no native English speakers who could draft a new label, so they copied it from someone else's 72 cell panel label.

Vic

Hi mcgivor,

Agree that this is a bit suspect,  especially for Poly PVs.   There are some 60-cell PVs with Vmps in the 33-ish range,  but believe that these tend to Monos.

Would bet that you would want to have the manufacturer confirm all of the spec values.  If one divides the 250 W by the stated Imp,  one does come up with 35.97 Vmp.

Also,  the stated Power Tolerance if +/-- 3%.   Most name-brand manufacturers have gone to,   --0 - + 5W,  or similar.

If you must buy these PVs I would,  at the very least,  write a Purchase Order,  stating the conditions of acceptance by you ...  although,  perhaps where you are,  such a document might have no standing,  in reality.   Also,  using the Standard  Flash Tube measurement,  is very,  very difficult for the average customer,  in the field.

IMO,   Vic

mcgivor

Don't think I would consider them when the manufacturer seems to not exist, there are better choices with names recognized by Morningstar's array caculator, all the panels I currently have are Schutten and so far so good so will stick with those.