[RE-wrenches] Future low Vmp

[Kent]

Nathan,

In the NREL report Photovoltaic Degradation Rates — An Analytical Review 
by Dirk C. Jordan and Sarah R. Kurtz 
<https://www.nrel.gov/docs/fy12osti/51664.pdf> the conclusion is that 
the 0.5% or so annual degradation of PV module output is mostly due to 
changes in PV module current. Other studies have come to the same 
conclusion. So, long term changes in voltage might not be worth worrying 
about.

Kent Osterberg
Blue Mountain Solar



On 4/10/2025 4:31 PM, Nathan J. Stumpff via RE-wrenches wrote:
> Hi wrenches,
>
> I used to do these kind of calcs all the time but am wicked rusty. 
> What assumptions do you use for future (degraded) hot temp Vmp of a PV 
> string to check if you will still be able to operate inside a given 
> MPPT range? Specifically interested in assumed yearly degradation to 
> Vmp, assumed actual operating cell temp, and if it is appropriate to 
> use STC value as the starting point and if not what would be better 
> (NOCT?)
>
> Thanks,
> -Nathan
>
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