[RE-wrenches] PV Watts for Of Grid Design?

[Dan Fink]

Hi Jeremy;

PV Watts works fine for off-grid. We generally use a 30-35% de-rate factor.

But in reality with us....we are all locked in on different 'tiers' of
systems......with L-16 or T-105 battery banks, you get locked in by
having to add batteries in sets of 8 (or sometimes 4, only rarely 2).
And locked in by PV modules strings of 3 modules. So by the time we
oversize everything, the de-rate factor is minor. PV is so cheap now,
and we're in sunny Colorado too....anymore we just tend to oversize
the PV array, keep the battery bank as small as possible, and use a
generator to extend autonomy time.


Dan Fink,
Executive Director;
Otherpower
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC accredited Continuing Education Providers
970.672.4342




On Thu, Feb 28, 2013 at 2:31 PM, All Solar, Inc. <allsolar at scswifi.net> wrote:
> Wrenches,
> I had a prospect send me PV Watts data for his future off grid home.  Of
> course we use PV Watts for GT systems all the time, but I have yet to use it
> for Off Grid system design. We use an old Dankoff Solar tool that has worked
> for years....
> Any thoughts on using PV Watts as a basis for this.  I guess the efficiency
> is the unknown here for me.
>
> Thanks!
> Jeremy
> All Solar
> CO, USA
>
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