48 volt panels?

[Phssthpok]

 I have two panels that I bought off Craigslist that list specs as follows:

Pmax    50W

Vmp     78V

Imp     .64A

Voc     102V

Isc     .79A

I think they're for a 48v nominal system voltage, but I've been searching all day and I just can't seem to find out what a typical Open Circuit Voltage would be on a 48 volt panel.

Does anyone here have any idea?

[DamonHD]

They'd probably do well for a 48V system with (say) an Outback MX-60 MPPT controller at a guess, but my system is all 12V and very simple (not MPPT) so I'm no expert.

Maybe without MPPT a Vmp of 55V would be a better match for PWM style charging, but the Voc is likely to be much higher anyway.

Rgds

Damon

[PaulJ]

   Voc on a 48V panel in full sun should be around 80V.

   The panels you have are probably intended for a higher voltage grid-tie application. They'll work fine (but with slightly lower efficiency) into 48V as long as your controller can cope with the higher Voc.

   Paul.

[scottsAI]

Think of it this way:

12v panels have OC voltage of around 20v.

Peak power at 17v.

Therefore 12 * 4 = 48, so 78v is correct.

Have fun,

Scott.

[independent]

Measure them with a DMM (digital multimeter) before you do anything else.

Open circuit voltage in full sun as well as closed circuit current--for kicks, probably literally if you aren't too careful.

Afterwards, check the junction box, again with your DMM, to see how they are wired. I have heard of 24v panels wired as 12v panels, so there's a chance you may be able to use them in a more accessibly sized voltage system.

[independent]

That came out wrong. I meant, I would measure it with a voltmeter before doing anything else as it sounds on the high side for a 24v setup but that sounds what they are for. hth