[RE-wrenches] Pathfinder vs. Suneye

Dana Brandt dana at ecotechenergy.com
Wed Oct 29 16:46:16 PDT 2014


Hi Allen,

Thanks for the assessment. I think that makes a lot of sense. I prefer to
be conservative with my grid-tied numbers, too. Maybe I'll just round down
the Suneye projections.

Dana

Dana Brandt
Ecotech Energy Systems, LLC
www.ecotechenergy.com
dana at ecotechenergy.com
360.318.7646

On Tue, Oct 28, 2014 at 3:38 PM, Allan Sindelar <allan at sindelarsolar.com>
wrote:

>  Dana,
> I'm not going to answer your question directly, but rather I'd like to add
> to Ray's comments. In short. use the SunEye for grid tie work; use the
> Pathfinder for off grid. If you don't do off grid (most installers don't
> any more, if they ever did) don't bother with the Pathfinder. Off grid
> seldom if ever deals with multiple roof angles, as modules aren't typically
> mounted on roofs.
>
> Details:
> 1. Grid tie is competitive, so you want the most accurate estimate of
> production. I believe the SunEye is more accurate, or at least more
> "liberal" in its output.
> 2. Your competitors will most likely use the SunEye, so you'll need to
> offer its level of apparent professionalism, as well as match their output
> projections.
> 3. For off grid, I want the inherent conservatism of the Pathfinder; for
> grid-tie, not so much. I have almost zero history of customers' off grid
> systems being undersized, in large part because of the inherent
> conservatism of the Pathfinder, combined with our 37º latitude, as Ray
> mentioned (meaning we're at the outer edge of the 6º latitude template
> spread), and also combined with our high-elevation, dry-air insolation
> often exceeding the standard 1,000 w/m2. Together this meant that my
> systems typically and routinely exceeded their projected output. Nobody has
> ever complained about that.
> 4. Grid tie customers never go on the roof with the designer/salesperson
> to look at a sunpath chart. They just want the results - a PV system that
> looks good and saves them money. Off gridders are usually way more involved
> in the design and customer education process. The Pathfinder sunpath chart
> is so simple to read that doing charts while picking an array site is a
> shared part of the educational part of the design/sales process. So it
> leads to the treasured "ah-hah!" moment when the client really gets what's
> going on, and gets fully engaged in the design of "their" system in the
> process.
>
> They're two different tools serving completely different purposes. I
> prefer the analog nature of the Pathfinder, but not for the usual and
> predictable reasons.
>
> Allan Sindelar
> www.sindelarsolar.com
>
>  *Allan Sindelar*
> allan at sindelarsolar.com
> NABCEP Certified PV Installation Professional
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Founder (Retired), Positive Energy, Inc.
> *505 780-2738 <505%20780-2738> cell*
>
>
>  On 10/28/2014 3:32 PM, Ray Walters wrote:
>
> I've not done a side by side comparison, but the Pathfinder seems to be
> slightly conservative, especially depending on which latitude sheet you are
> using.  I sometimes switch sheets and try both, when the latitude is close
> to falling between (ie 37 deg, and there is 37 to 43 sheet or a 31 to 37
> sheet)   Checking against actual sun locations at the solstices, it seems
> to be close, but I think they would rather err on the side of caution.
> I've used the Path finders for decades, and find them ideal for discussing
> shading issues on site with the customer, as every one can look at it at
> the same time.
> For more complicated shading analysis, I can see the Suneye being more
> useful.  Depending on the situation, I could see using both, but the
> Pathfinder is better for off grid, as we don't have accurate insolation
> values at these remote locations, so detailed analysis has limited value
> anyway.  We're primarily looking at which trees need to be trimmed.
>
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer303 505-8760
>
> On 10/28/2014 3:19 PM, Dana Brandt wrote:
>
>   Hi Wrenches,
>
>  We've been using the Pathfinder along with the Pathfinder Assistant
> software for several years and mostly like it. My concern with it is
> there's no way to combine two or three shading images to account for a
> string of modules spanning those different shading conditions. I've spoken
> with the Pathfinder folks and they don't seem to understand or acknowledge
> that limitation. How have you dealt with this?
>
>  So I bought a Suneye. Their software can apparently calculate string
> shading including multiple solar access readings.
>
>  I took both the Pathfinder and the Suneye out on my next site assessment
> and have run the results of side by side measurements. The Suneye is
> showing about 10-15% better solar access for each measurement that the
> Pathfinder Assistant software. I'm concerned to see such different numbers.
> Has anyone else done a side by side comparison? What have you seen?
>
>  Thanks,
>
>    Dana
>
> Dana Brandt
> Ecotech Energy Systems, LLC
> www.ecotechenergy.com
> dana at ecotechenergy.com
> 360.318.7646
>
>
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