[RE-wrenches] SE or SW

Tue May 14 18:05:25 PDT 2013

PV Watts does not account for shading / etc.
The NREL SAM model does a better job but is complex (as are most of the good models).

We use PVSyst which has models for module level electronics.

Best Regards,

John Berdner
General Manager, North America

SolarEdge Technologies, Inc.
3347 Gateway Boulevard, Fremont CA 94538 USA  (*Please note of our new address.)
T: 510.498.3200, X 747
M: 530.277.4894

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of August Goers
Sent: Tuesday, May 14, 2013 5:51 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] SE or SW

Does PVWatts really account for hourly weather data such as overcast conditions in the afternoon? I think it just accounts for average solar radiation for a particular location on a monthly basis but I could be wrong. Anyone care to chime in?

-August

August Goers

VP, Engineering

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On Tue, May 14, 2013 at 4:26 PM, Jesse Dahl <dahlsolar at gmail.com> wrote:<http://www.luminalt.com/>
We do tend towards clear mornings and clouding up in the middle of the day. Today was a good example of it.  I did use PV watts and didnt see a big difference between the two.

Thanks Benn

Jesse

Sent from my iPhone

On May 14, 2013, at 6:10 PM, Benn At DayStarSolar <benn at daystarsolar.ca> wrote:

> Jesse,
> A good decision can be based on, among other site/load specific details, the site's "micro-climate".
>
> Do they tend to have clear mornings and cloudier afternoons/evenings?
> ...or cloudy/foggy mornings and clearer afternoons/evenings?
>
> Maybe throw the different directions into PVWatts and see what it says, since it is based on weather history (isn't it?)
>
> Good luck.
> benn
> Sent from a 'smart' phone, with touch screen keys. Please excuse shortcuts and typos.
>
> On 2013-05-14, at 4:34 PM, Jesse Dahl <dahlsolar at gmail.com> wrote:
>
>> Hello,
>>
>> I was asked to look at a site today for a homeowner looking for a grid-tie with battery-back up. They are Doomsday Preppers for lack of a better term and want certain loads if and when the grid goes down for good. Aside from parts selection, they have two roof lines, one facing SE one facing SW. the SW is very low slope and is only accessible with a ladder and climbing on the roof, the other is SE, much steeper slope and accessible from the ground or deck.  I mention the access because of snow removal. We had lots of snow last year and I spent lots of time on my roof removing 8" snow falls.  Both have good solar access.
>>
>> I'm inclined to chose the SE roof line, but I am interested in arguments for the SW.
>>
>> Thanks!
>>
>> Jesse
>>
>> Sent from my iPhone
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