I have to agree. We have done off-grid for 30+ years, so it was a very
simple transition for us to also do on-grid because the system design and
configurations are much simpler.
Over the past few years we have seen more mistakes by those that are only
grid-tie familiar or certified when designing off-grid. I think the single
most common mistake they make is to use the yearly average insolation
instead of worst case. Other very common mistakes we see in the many systems
we have refurbished or redesigned are failure to account for battery
temperatures vs capacity and charging, proper battery sizing, and phantom
loads.
Apparently NABCEP does not go into off-grid systems very deeply, perhaps
because the market is smaller and they can be much more complicated.
..................................................................................................
Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..................................................................................................
----- Original Message -----
From: "Dana" <d...@solarwork.com>
To: "'RE-wrenches'" <re-wrenches@lists.re-wrenches.org>
Sent: Tuesday, November 24, 2009 9:40 AM
Subject: [RE-wrenches] Nabcep - grid tie---Off grid
Just got to weigh in on this one.
It cracks me up to see the grid tie generation's attempts at off grid
design. It is such an experiential design mode. It can be conceptually
taught in a class. But it has to be lived to really be made whole. The
finer
OG designers I know have almost all lived off grid. It is like
transmission
repair mechanics! I used to do tune-ups and do a timing chain on occasion
long ago, but fix a transmission, either automatic or manual, forget it,
not
me as it was to specialized.
Perhaps you have a good idea here, Jay. I hate to see an additional layer
added here but you bring a good point to light. I am currently the #4
designer to work on both a SHW and Grid tie with battery backups that do
not
work and the battery bank is cooked and was not large enough to do much
more
than a couple of hours of back up at most though the client was promised
that it would support the house for several days. It is sad to see people
taken by NAPCEP Certified and non certified installer/designers who wade
in,
make more of a mess, charge a bucket load and wander off citing the owner
is
asking too much.
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