[RE-wrenches] Actual losses from dissimilar orientations onsingle inverter

[jay peltz]

HI Sky,

I sure hope the data doesn't take a few more decades!

jay

peltz power
On Sep 12, 2008, at 8:26 PM, Sky Sims wrote:

> August makes a good point. There really isn't much solid info on the
> topic of dissimilar orientations.
>
> In the experiments I've conducted using different orientations and  
> tilts
> on the same strings the production almost exactly matches the average
> projected production across the orientations and tilt.
>
> In regard to using mix matched modules in parallel strings I haven't
> seen any noticeable difference in performance either. Of course this  
> is
> an advanced technique and requires an awareness of string voltages and
> amperages in order to avoid excessive power clipping. The biggest
> problem with using different manufacturers panels with each other
> appears to be more bureaucratically driven rather than performance
> based.
>
> What I mean to say is that because the manufacturers are unlikely to
> provide a written endorsement allowing you to use their panels in the
> same string with someone else's, you may have trouble with a  
> bureaucrat
> requiring that endorsement.
>
> There is a lot of rumor floating around about how important it is to  
> use
> the same panels and the same orientations and tilts. And I agree it is
> important, but there may be circumstances that over ride those rules.
>
> I've had many systems where for esthetic or available space reasons a
> panel or 2 in a string of modules was put at an entirely different  
> tilt
> and orientation. I've played quite a bit with it and haven't noticed  
> any
> reduction in performance that would warrant the elimination of what
> might be 10 to 30% of the string or perhaps even the entire string.
> However with inverters like enphase coming to market it becomes easier
> to ensure that every panel in a string is at the same orientation and
> tilt.
>
> I always recommend the best tilt and orientation possible but sites  
> and
> circumstances coupled with other details specific to the site  
> sometimes
> force us to go with less than optimal string placement practices. A
> healthy well rounded understanding is important and I don't feel that
> the industry has done enough to create that understanding yet. Best
> practices have certainly been promulgated but the context has not been
> fully explained or explored yet.
>
> Inverter reps and installation reps and panel reps have made many many
> representations based on their best guesses and in some cases what  
> they
> have seen first hand. We the implementers are the guinea pigs, get  
> used
> to it. Thankfully the kinks are getting worked out.
>
> Perhaps in another couple decades when things settle down we'll have
> properly documented studies of mix matched panels, orientations and
> tilts. Of course by then things will be so completely different that  
> it
> wont matter any way.
>
> My 2 cents,
> Sky Sims
> Ecological Systems
> http://www.ecologicalsystems.biz
> 220 County Road 522
> Manalapan, NJ 07726
> 732-462-3858  toll free)866-759-7652  fax)732-462-3962
>
> -