Voltage drop musings [RE-wrenches]

[Lynne A Carter]

Bill
The "54 volt system that was experience controller voltage issues."  Was
that system in CA or Carolina?
LYN

Lyn at solarvillage.com
Solar Village Institute inc.
PO Box 14
Saxapahaw, NC  27340
Tel. 336-376-9530
Fax. 336-376-1809
www.solarvillage.com

----- Original Message -----
From: Bill Brooks <billbrooks7 at earthlink.net>
To: <RE-wrenches at topica.com>
Sent: Wednesday, May 02, 2001 10:08 PM
Subject: RE: Voltage drop musings [RE-wrenches]


> To all,
>
> Lots of numbers are being thrown around about MPPT controllers without a
lot
> of good test data. Beware of manufacturers claims. Having lived with a
> battery-based grid-tied system for over two years with lots of operating
> experience, I believe that an MPPT controller would provide no benefit in
> this climate.
>
> Not necessarily so in other climates, but MPPT controller are really
better
> suited for stand-alone systems. Be very careful about using higher voltage
> battery strings. C-40s and other controllers have a very real upper
voltage
> limit that will bite you. Just returned from check a 54 volt system that
was
> experience controller voltage issues.
>
> It's nice to throw around a lot of numbers, but until you constrain the
> application, it is way to broad of a statement to say that MPPT
controllers
> are the way to go. When are they going to get UL? The controller does not
> exist in my book until that happens.
>
> Bill.
>
>
> > -----Original Message-----
> > From: jay peltz [mailto:jay at asis.com]
> > Sent: Wednesday, May 02, 2001 9:11 PM
> > To: RE-wrenches at topica.com
> > Subject: Re: Voltage drop musings [RE-wrenches]
> >
> >
> > Hi Joel,
> >
> > One way is to increase the number of batteries in the system.
> > This increases the
> > operating voltage ( more watts) without the need for a MPPT
> > controller.  48v systems
> > are pretty easy as you add another 6v ( if you are using 6v
> > batteries.  If you are
> > using 2v cells, then maybe 8v would work better?) battery to the
> > system, works
> > pretty slick- cell voltage is lower, overall voltage is higher=
> > more watts to the
> > grid.
> >
> > And yes many people are using the MPPT controllers to get around
> > this problem called
> > "batteries".
> >
> > Jay
> > Peltz Power
> >
> > Joel Davidson wrote:
> >
> > > Yes, I have 32 each 70-watt modules 4 in series for nominal 48
> > volts. The C40 is
> > > set at 54.8 volts so that voltage flows downhill to the
> > inverter which is set at
> > > 54.4 volts.
> > >
> > > Note that this is a grid tied net metered PV system with
> > batteries - not a stand
> > > alone or standby PV system.
> > >
> > > The problem with a net metered PV system using the SW-series
> > inverter with
> > > batteries is that the inverter operates at the nominal battery
> > voltage, not the
> > > optimum PV array max power point. Since the batteries are just
> > sitting there
> > > being float charged and power passes through the inverter to
> > the load and grid,
> > > can the SolarBoost send max power from the array to the
> > inverter? Has anyone
> > > used a SolarBoost to get around this SW inverter shortcoming?
> > >
> > > "Travis Creswell, Ozark Solar" wrote:
> > >
> > > > Joel,
> > > >
> > > > Are you trying to say you have thirty two 70 watt modules?  8
> > strings x 4.?
> > > > amps = 30 + amp array.  You will need two Solar Boost 3048's.
> >  Better yet
> > > > put 16 on the C40 and 16 on the SB3048 (you'll need a DVM
> > option for it too)
> > > > and compare the outputs.   Do you have a Fluke 36 ammeter?
> > If you don't
> > > > borrow/buy one (~$250 and you really should have one) and
> > compare it's amp
> > > > rating to your C40's.  I almost always find the C40 DVM's to
> > read amps ~10%
> > > > low.  I have found the SolarBoost products to be very
> > accurate.  (Never pass
> > > > a chance to beat up on Trace, just kidding, maybe)
> > > >
> > > > Oh yeah, your question,  you should produce up to 30% more
> > amps when its
> > > > colder, say less than 40F.  In the summer you will only see a
> > 10% (maybe)
> > > > difference when the batteries are under 50 volts in the
> > cooler mornings
> > > > which you won't see since you are grid tied.
> > > >
> > > > Travis Creswell
> > > > Ozark Solar
> > > >
> > > > ----- Original Message -----
> > > > From: "Joel Davidson" <joeldavidson at earthlink.net>
> > > > To: <RE-wrenches at topica.com>
> > > > Sent: Wednesday, May 02, 2001 6:51 PM
> > > > Subject: Re: Voltage drop musings [RE-wrenches]
> > > >
> > > > > Is the SB3048 a current boosting battery charger or a PV
> > array max power
> > > > point
> > > > > device? I have 8 each 4-module series strings of Siemens
> > SP70 modules
> > > > feeding
> > > > > into a C40 and then into a net metered SW4048 with a small
> > backup battery
> > > > bank.
> > > > > The batteries just sit there (pulling the inverter off max
> > power point),
> > > > but the
> > > > > net metered load is the grid so it can take all the PV I
> > produce. Right
> > > > now
> > > > > (4:30PM) my C40 digital meter says 16 amps at 54 volts
> > equals 864 watts.
> > > > Will I
> > > > > produce 19.2 amps at 54 volts or 19.2 amps at 45 volts with
> > the SB3048?
> > > > >
> > > >
> > > > - - - -
> > > > To send a message: RE-wrenches at topica.com
> > > >
> > > > Archive of previous messages:
http://www.topica.com/lists/RE-wrenches/
> > > >
> > > > List rules & etiquette:
http://www.mrsharkey.com/wrenches/etiquete.htm
> > > >
> > > > Check out participant bios: www.mrsharkey.com/wrenches/index.html
> > > >
> > > > Hosted by Home Power magazine
> > > >
> > > > Moderator: michael.welch at homepower.com
> > > >
> > >
> > > - - - -
> > > To send a message: RE-wrenches at topica.com
> > >
> > > Archive of previous messages: http://www.topica.com/lists/RE-wrenches/
> > >
> > > List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm
> > >
> > > Check out participant bios: www.mrsharkey.com/wrenches/index.html
> > >
> > > Hosted by Home Power magazine
> > >
> > > Moderator: michael.welch at homepower.com
> > >
> >
> >
> >
> > - - - -
> > To send a message: RE-wrenches at topica.com
> >
> > Archive of previous messages: http://www.topica.com/lists/RE-wrenches/
> >
> > List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm
> >
> > Check out participant bios: www.mrsharkey.com/wrenches/index.html
> >
> > Hosted by Home Power magazine
> >
> > Moderator: michael.welch at homepower.com
> >
> >
>
> - - - -
> To send a message: RE-wrenches at topica.com
>
> Archive of previous messages: http://www.topica.com/lists/RE-wrenches/
>
> List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm
>
> Check out participant bios: www.mrsharkey.com/wrenches/index.html
>
> Hosted by Home Power magazine
>
> Moderator: michael.welch at homepower.com
>

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9
Or send an email To: RE-wrenches-unsubscribe at topica.com
This email was sent to: michael.welch at homepower.com

T O P I C A  -- Learn More. Surf Less.
Newsletters, Tips and Discussions on Topics You Choose.
http://www.topica.com/partner/tag01
==^================================================================