I am placing this inquiry out to see if anyone else has experienced a similar
An electrician friend near Taos, NM, installed a Conext XW+ 6648 inverter on a
large 2nd seasonal (remote stand alone PV supplied) vacation home, (used less
than 10 weeks per year), it has a large 48 VDC AGM battery (40+kW-Hr) and
almost a 7.0 kW PV Array and a back-up LP gen-set. It has a Xantrex accessories
: Com-Box, charge controllers, bat monitor, etc.
The anomaly this system exhibits is that - when the owners are infrequently
present - during each evening, for about 90 seconds - the 120vac lights get
noticebly brighter. After this brief event, the lights exhibit normal behavior.
No lights or appliances are functionally damaged.
It is more of a nuisance than an actual problem. This usually happens between
9:30 and midnight. The timing seems to be arbitrary - as no known load either
turns on or turns off in conjunction with this event.
Xantrex has been consulted and the inverters firm ware has been upgraded and
they even sent a replacement inverter control board, which after its
replacement nothing changed.
As this is quite late at night and has been happening both in winter and in
summer months, it is not presently believed to be associated with the PV
modules or charge controller.
Conventional wisdom implies, that if there is some significant load was cycling
in the background - the lights would dim - not brighten. I have never heard of
anything like this and was wondering- if any had. There are no known large
capacitive loads on the system.
Any one seen anything similar, I was asked - as I have been doing systems in
New Mexico since 1995 and I guessed it was a well/ water pressure bladder tank
system related issue . . . but the installer has witnessed this, at night
when the water pump and well remained off. ?
Item 2) some weeks ago, it was noted on this RE-Wrenches thread that some
ballast blocks, 4” x 8” x 16” were starting to suffer decomposition and a
solution was sought, I guessed that this might be due to water seepage and
repeated freezing and thawing.
Has anyone used an inexpensive masonry sealer painted on the blocks, to stop
water wicking to the concrete ballast blocks? There is very thick cinder block
paint (UGL) for cinder block foundations that would be quite expensive and
polyurethane is very pricey too - I would like to recommend that works
successfully and is economical for existing installations rather than replacing
hundreds of blocks?
Daniel O. Duffield
NABCEP Certified PV Installation Professional (2005)
NM licensed Commercial Electrical Contractor EE98/ER01
IEEE member 23 years
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