Larry,
The voltage of the HIT 190 or HIT 200 is very similar to three 36-cell
modules and based on the 75-volt spec it seems like they were
considering that possibility. With the high voltage conversion down to
12-volts the charge controllers are experiencing more heat than they
would with the same power at a lower input voltage or the same power
with a higher output voltage. At the higher voltage, the width of the
pulse in the PWM goes down and the RMS current in the switching
transistors goes up. I'll bet the same module and controller would be
more reliable in a 24-volt system. Pushing the limits, the way we do,
gets us in trouble.
Kent Osterberg
Blue Mountain Solar, Inc.
Starlight Solar, Larry Crutcher wrote:
I believe the issue we had has to do
with using the Sanyo high voltage PV module. As Kent points out, we
were operating the controller at the design limit. I don't believe
it is suited to do that as we have other Morningstar MPPT controllers
working fine for several years now with lower voltage PV modules. BTW,
the MPPT failures were in systems that we designed and installed using
the Sanyo's.
The main reason we started using
this controller is for 12 volt systems with a single high voltage
module. We use other controllers when the Voc is less than 40
volts. Warren, are any of the 200 units you sold last year used with a
200 watt Sanyo other high voltage PV module(s)?
Larry
-----
Original Message -----
Sent:
Monday, January 24, 2011 11:05 AM
Subject:
Re: [RE-wrenches] 10A Charge / load controller
All controllers have failures – most commonly due to
user/installer errors. Of all the controllers we sell, Morningstar have
been by far the most trouble free and has the best no-hassle warranty.
We have probably sold/installed around 100 to 200 of the
SS-MPPT-15 controllers over the past year or so, and have seen almost
zero problems that were not caused by a bad installation of some sort.
Just on a side note, of all the controllers of all brands we have sold
over the past decade, probably 3/4 of those returned by end users as
“not working” has nothing wrong with them.
Sent: Monday, January 24, 2011 10:39 AM
Subject: Re: [RE-wrenches] 10A Charge / load controller
The
spec sheet for the SS-MPPT says 75 volts maximum open circuit. Maximum
PV power: 200 watts for 12-volt batteries and 400-watts for 24-volt
batteries. While it is supposed to be protected from PV overload and
PV high voltage, it doesn't seem surprising that failures that have
been observed are in systems that are pushing on these limits.
Fortunately, Morningstar stands behind their product.
Kent Osterberg
Blue Mountain Solar, Inc.
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