[RE-wrenches] Pathfinder vs. Suneye

August Goers august at luminalt.com
Wed Oct 29 16:53:49 PDT 2014


All –



Just a couple of quick comments – we’ve been using both Pathfinders and
Suneye’s for several years. We’ve now primarily switched to the Solmetric
Suneye for ease of running the full analysis report. A while ago we
compared the same sites back to back between the Suneye software and
Pathfinder Assistant software. We actually found that the two were within a
couple/few percent of each other but that the Suneye was more conservative
(ie the Suneye report showed more annual shade than the Pathfinder). Note
that you need to use the Pathfinder software to accurately analyze azimuths
for anything other than South. A West facing array, for example, will not
compute properly but just adding up the shade numbers under the dome.



Best,



August



Luminalt



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Dana Brandt
*Sent:* Wednesday, October 29, 2014 4:46 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Pathfinder vs. Suneye



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 Engineer

303 505-8760

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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