SB304- SB50 limits [RE-wrenches]

[RV Power Products]

Wrenches,

I'm am obviously very pleased that you like Solar Boost(tm) products and use
them. We very much appreciate your business.

The products were designed primarily for 24Vin-24Vout or 48Vin-48Vout to
provide the highest
level of overall efficiency. When the modules have more power to give than
might be
available from a conventional controller, the Solar Boost controller
operates the modules at a higher voltage (Vmp) to extract more power. A high
efficiency DC-DC power converter then lowers this higher input voltage to
battery voltage at the output. But, as with all switching type power
converters, some power is lost in the conversion process. When conditions
are such (at high module temperature) that extra power isn't available the
Solar Boost stops switching type power conversion and reverts to a
straight-through resistive connection as with a convention controller to
provide as much power as possible to the batteries. With higher input
voltage (i.e., 48Vin / 24Vout) the DC-DC converter must always operate, even
when here technically is not "extra" power available. It therefore wastes
some power when extra power is not available compared to a 24Vin / 24Vout
system. For this reason, we frankly didn't expect voltage the step down mode
to be so popular...

The reason power handling capability is lower in the voltage step down mode
is that all the components have limits; current, voltage, power and
temperature. Devices that have a 30A maximum safe limit still retain this
limit even though output voltage is lower. We endeavor to deliver
high quality robust products that don't run devices to the edge of their
limits, at what we try to have be a reasonable cost.

We will be producing MPPT products of higher power and voltage. You could
help us with
this by providing specific guidance relative to exactly what it is you want.
What
output voltage, output current, and input voltage would you like to see. My
past conversations with Bob-O, have lead to the desire for an SB3048 like
product that could be 48V input with 24V 50A output. Would something like
this meet a majority of your requirements? If your preference is to discus
this off the list, my personal email is rick at rvpowerproducts.com or you can
call me at 760-944-8882 or 800-493-7877. Our primary goal is to provide you
with the finest products and service, and I would very much appreciate your
feedback on this topic. We will listen to you and make every effort to
produce the products you need.

Rick Cullen
RV Power Products, Inc.
Providing Quality MPPT Solar Charge Controllers.
www.rvpowerproducts.com
rick at rvpowerproducts.com

----- Original Message -----
From: Todd Cory, Bald Mtn. Solar <toddcory at jps.net>
To: <RE-wrenches at topica.com>
Sent: Saturday, November 10, 2001 10:12 AM
Subject: Re: SB304- SB50 limits [RE-wrenches]


> I agree, 30 amps at 24 volts is pretty useless as the capacity is just
> sufficient. I wonder why this controller is not built at the 50 amp
capacity
> like the 5024?
>
> Is Rick on the list? Maybe he would like to explain?
>
> Todd
>
>
> Lawrence Elliott wrote:
>
> > Lee. Yes I have run into the same problem. I like the RV allot and have
> > been using them almost exclusively on larger systems but they are badly
> > limited.
> > I use allot of SR100's and a twelve panel array is common. On a long run
> > using the 3048 it's useless since even this array is limited by the 3048
> > to less current than can be produced at 24. I have a system going in
> > that is 48 with two 12 panel SR100 and I will need to run two RV's at
> > slightly over half current since putting both arrays into one controller
> > exceeds the current just a little. Adds more cost to a system that could
> > be simplified.
> > Rick had better take the hint and get on the stick. The industry needs
> > something better. Hint! Hint!
> > Larry Elliott
>
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