[RE-wrenches] MPP Tracking Notes: Solectria PVI13kW, Module VMPs

[Dave Click]

Hi all,

Just passing along a correction from Solectria on this issue. Since Dec 
2010 these inverters have had a 205V+ window; apparently these units 
just had an old label on them.

Dave

On 2012/11/29 9:39, Dave Click wrote:
> Hi all,
>
> I did an inspection recently that had 3 Solectria PVI13kW units
> installed. I was surprised to note that the MPPT window on the nameplate
> was 225-380VDC, as the online spec sheet and manuals all note a
> 205-385VDC window. When I asked tech support about this, they replied
> that the window has been 225-380 for a while. The rep was surprised that
> the online documentation is wrong and since my inverter was almost a
> year old, it's apparently been wrong for a year. No update as of today
> either, even though it's been a few weeks since I called. So, just an
> FYI in case you're looking to spec those inverters.
>
> This inconsistency ended up being a big deal on this inspection, as the
> module manufacturer chose to custom-label each module with its actual
> output. Turns out that the actual VMP values were about 9% lower than
> the spec sheet indicated, which pushed the expected summer array VMP
> down to around 217VDC. I'm not sure how widespread this tolerance issue
> is, but since many manufacturers don't always provide flash test
> results, and UL 1703 allows these values to vary by as much as 10%, this
> is another good reason to try to max out your string sizes and stay as
> far as you can above the MPPT minimum voltage. These modules have a
> power tolerance of +/-3%, which they accomplish with higher current
> values that in some cases actually exceeded the 10% UL tolerance limit!
> After 20 years, the VMP on these modules will be about 20% lower than spec!
>
> Dave
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