Large residential system [RE-wrenches]

Solar Ray remotech at taosnm.com
Fri Dec 12 10:58:26 PST 2003


Hi;

Haven't checked my email lately, but I thought I should add that we've done
a couple of systems with quad SW inverters. I know they're not as cool as
the Outback stuff, but since you have two load panels, you could feed one
leg of each panel with an SW. We've had good luck with our quad SW systems,
and
it could possibly save some $$$.
Definitely over design the system, they always will almost double your
original  load calcs
in a couple of years.
I'd keep the 40kw genny, once you calculate altitude losses, battery
charging
and your pass thru for AC loads you'll find you might not be as oversized as
you thought.
Our limited experience with DC gennys (Wind river ?) was not good. AC genny
with bypass switches is still the best compromise I think.

Ray

Solarray.com
----- Original Message ----- 
From: "Gary Higbee" <gary at windstreamsolar.com>
To: <RE-wrenches at topica.com>
Sent: Wednesday, December 10, 2003 5:44 PM
Subject: Re: Large residential system [RE-wrenches]


> Darryl, Jay, and Wrenches:
>
> Thank you so much for the responses. It's always interesting to walk into
a
> system I did not design and attempt to make things right. If you haven't
> been following the thread see the previous posts (saving bandwidth
here...).
>
> I have an appointment tomorrow morning with the owner to make a proposal,
> and it will be something like:
>
>
> INVERTER
> Change out the two SW4024's for a stack of four VFX3648's, with a quad
100A
> bypass on the AC end. The dramatically higher surge, 14kW operating, and
> vastly higher battery charge rate would be a much better match for the
needs
> of this house, and for the (unfortunate) reality of the existing 40kW
diesel
> generator.
>
> BATTERY BANK
> Go with a an appropriate battery bank, giving the owner options. A 48-volt
> string of the Surette 4KS-25P cells gives us around 1350 Ah (about 32kWh
at
> 50% DOD). We'd be cycling like crazy with high loads, so I give the owner
> the option of adding a second string OR running the generator when the
loads
> are extreme.
>
> PV
> The current 2500 watt array could be substantially increased in size, and
> would scale well with summer A/C needs (I'll strongly push more passive
> cooling, too!). Adding another 5-7.5kW of PV might almost eliminate the
> substantial generator run time to feed the A/C on those hot SUNNY days.
>
> Speaking of PV, the existing Outback MX60 was wired with the input of 15
> Sharp 165's, set up as five strings of 3. Open-circuit is just under 130
> volts, and I'm told this is fine (the spec has been raised). BUT whoever
set
> the thing up has the MX60 output into the 24-volt system. Hmm, just a
quick
> calc of 2475 watts/24 volts gives about 103 amps. Was anyone home?? Well,
we
> either must go to 48 volts, in which case we're fine, OR take the modules
> up, rewire into two sub-arrays, run extra wires, and install a second
MX60.
> I vote we move forward to 48 volts.
>
> GENERATOR
> Keep the 40kW for now, unless a later study shows that we can make the
fuel
> economics pay off to change the unit out for something in the 20kW range.
> With the Outback quad 100A bypass there will be plenty of fallback if
> something fails. Who ever talked the owners into this monster...
>
> HYDRO
> Complete the Harris PM hydro. It looks like we'll push 500 watts or a bit
> more, which should help a great deal when the seasonal water system is
> running.
>
>
> Any other thoughts?
>
> Again, thank you Wrenches.
>
> Gary
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       Gary Higbee  (gary at windstreamsolar.com)
>                      (541 )607-1818 (Eugene)
>                         (541) 954-3881 (Cell)
> Solar, wind, and hydro site analysis and system design
>     Components dealer and installation assistance
>  Energy Trust of Oregon contracted system inspector
>  ~ WindStream Solar (www.windstreamsolar.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
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

TOPICA - Start your own email discussion group. FREE!
http://www.topica.com/partner/tag02/create/index2.html
--^----------------------------------------------------------------






More information about the RE-wrenches mailing list