At 19:39 -0400 1/9/11, Jason Szumlanski wrote:
Sorry - I missed the 4 days part of your post. I'm not sure where you
came up with 4 days - sounds kind of arbitrary.
Any chosen time is arbitrary. Maybe I should have chosen a month.
700 amphours. Dead flat 12 volt battery. I often use 4 days
I never, never recommend taps of any sort, but sometimes we have to satisfy
the needs of the customer. If any taps are done in any manner I would
recommend AT LEAST an annual reconfig of the taps.
To reduce and/or eliminate the imbalance of the 12 volt and 24 volt taps,
you could install a 12
As far as I know, The DC/DC and the Equalizers do basically the same thing
(step up or down). I recollect that the Equalizers are adjustable and can be
used as a load dump. Enermaxer comes to mind. It's been a long time...
but a refresher will be gladly accepted from those in the know.
Rob
What the Vanner Voltmaster equalizer does is track the voltage differences
between two parts of the string, and provides current from the other part to
the first part when needed. If a tap decreases the voltage in part of the
string, the other part of the string is used to help make up for it
On T-105 battery banks, I've used taps with alligator clips so the tap could
be moved every few days to power 1 amp or less loads. The taps worked
because I equalized the battery bank every month. I've used voltage-dropping
resistors (simple and cheap), Vanner equalizers (ambulance grade
Correct. As a mobile RE dealer and service center, I see quite a few 24 volt
systems with Vanner or other equalize type converters. As 12 volt current
increases it causes one battery voltage to drop. The equalizer then shares
current from the 24 volt tap to the 12 volt tap to maintain equal
Wrenches,
After Hurricane Irene left a lot of people without power here in the
Northeast, customers who have grid-tied systems are asking about some
battery backup to power some essential loads.
We have used Sunny Islands but they require either 2 Sunny Islands or
a step up transformer
Yes, there should be an uptick in at least inquiries about solar backup here in
the NE.
I went to a site in CT where I was called in to see why the customer was upset
about why her backup batteries went dead when she was told the solar would stay
on line and charge them during what is now week
I am merely a solar bozo.
One correction, I think it shares current from the second 12 V tap, not the
24 V tap.
I do not know if the equipment is capable of an equalizing scheme whereby it
can tap 12 V and 24 V off the same 48 V string (per the original question in
this thread), but a quick
Hi Larry,
Magnum MS PAE inverters do indeed shift the inverter output frequency
when the battery is full in order to disconnect grid-tied inverters used
in AC coupled systems. It was designed to work in conjunction with a DC
diversion load - which is recommended if the system is larger than a
Brian,
Could you speak a bit more to this, please? My understanding is that
the need with a string (or, I suppose, micro-) inverter and a
battery-based inverter is for a way to disconnect full batteries
from being overcharged when the grid is down and sell is disabled.
Allen,
The other inverters do not simulate the SI. The SI can be paired with a SB
such that there is some degree of proportional control of the SB output
power via frequancy shifts generated by the SI. Consult SMA documentation of
SI operation available on-line at SMA website.
Other inverters
This all works fine, until you fire up a generator to charge batteries. If the
generator remains within voltage and frequency limits, you stand a good chance
of overvoltaging the batteries. In this situation it is best to disable the
utility-interactive PV system while charging batteries from
HI Larry,
I'll chime in here with the other option, ie no batteries at all.
Instead its a back up generator.
I've found them to be much cheaper, and if you are expecting a longer outage
then weather is usually a problem ie its overcast and therefor you'll need a
backup for your battery system
There is only one 12 volt tap and one 24 volt tap plus ground. Picture two 12
volt batteries in series for 24 volts with the center going to the 12 volt tap.
The only other positive voltage source is the 24 volt connection. The equalizer
pulls from that terminal to maintain equilibrium between
Allan,
You're not the only one with your eyes spinning here. Let me clarify a bit as I
think you are making it more complicated than it is. There is no need for a
manual switch. The GT inverters feed into the sub panel which is being fed by
the Magnum. Since the Magnum is fed by the main panel
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