[RE-wrenches] Voltage degradation

[jay peltz]

HI Drake,

Its unlikely that all of the wattage degradation of the module would be in volts only.
In conversations I've had with experts, most numbers appear to be 1/2 volts and 1/2 amps.

But if you can get your modules to get a 20% over there is no draw back except a small % efficiency loss from the higher Vmp.

thanks,

jay

peltz power

On Apr 6, 2010, at 1:58 AM, Drake Chamberlin wrote:

> Esteemed Wrenches, 
> 
> How much voltage overhead should we have available on our arrays to allow for inverters not to fall out of their DC voltage operating range?  Since the module power degradation is 20% over the warranty period, I usually shoot for a module voltage that can drop 20% and still be within the MPPT range of the inverter under the average high temperatures, since most of the degradation is in voltage.
> 
> Am I being too conservative with this number?  It always pushes the number of modules to the top of what is allowable on the string for the extreme low.  
> 
> Thanks,
> 
> Drake Chamberlin
> Athens Electric
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