[RE-wrenches] Heinz 57 off-grid array

Phil Undercuffler solarphil at gmail.com
Mon May 3 07:46:57 PDT 2010


Whether you rebuild the system using existing equipment or start over again
with all new gear, I strongly suggest building a simple relay logic control
to prevent both pumps from running at the same time.  Toilet flushes,
grinder activates just as well pump kicks on....that's a pretty hefty load
for any system, and will force you into far more inverter than this client
otherwise needs.  Just decide which pump is most critical to run, and use
relays to prevent the other pump from kicking on until the first job is
finished. Might need to install more buffer for the second system -- larger
or multiple pressure tanks, or ___ (I don't want to picture what the second
system could use, sorry. Too close to breakfast).

I know this may sound obvious after the fact, but you'd be surprised how
many folks miss this.

Phil Undercuffler






On Mon, May 3, 2010 at 8:21 AM, Dana <dana at solarwork.com> wrote:

>  I see several challenges here:
>
> ·        You sure do not want both pumps on at the same time or total shut
> down will result.
>
> ·        The 2HP pump is 24 amps at 120VAC or 12 amps at 230 VAC, either
> way 2.7KW continuous draw and start up surge at 2-4 times [5.4KW –
> 10.8KW]that?
>
> This will be more than a light dimmer.
>
>
>
> I think the mix and match was just covered here with compromises in the
> assorted modules.
>
>
>
> I s there a backup generator? Could this grinder and water pump go direct
> to that on a pressure or float switch start?
>
>
>
> If you are a code compliant installer then you probably are faced with a
> start over.
>
>
>
> I have a client that we are doing just that right now and they are glad to
> do this. The 2 – 30 watt PV modules just will not get them and 2 laptops
> through the winter any more…
>
>
>
> Thanks,  Dana Orzel
>
>
>
> Great Solar Works, Inc
>
> E - dana at solarwork.com
>
> V - 970.626.5253
>
> F - 970.626.4140
>
> C - 970.209.4076
>
> web - www.solarwork.com
>
> Responsible Technologies for Responsible People since 1988"
>
>
>
> *From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
> re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Bob Clark
> *Sent:* Sunday, May 02, 2010 2:29 PM
> *To:* re-wrenches at lists.re-wrenches.org
> *Subject:* [RE-wrenches] Heinz 57 off-grid array - What should I do with
> the solar modules?
>
>
>
> Wrenches:
>
>
>
> We were called to assess the status of an off-grid system that is not the
> worst I have seen, but it comes close.
>
>
>
> I have some preliminary thoughts about system redesign, but would like to
> hear from the Wrenches about the array.
>
>
>
> *Givens:*
>
> We will not install anything unless it is to code.  It is obvious that none
> of the existing system was installed to code.
>
> We will use the existing 24V battery bank consisting of 8, Trojan L16s.
>  The batteries are still “relatively fresh.”
>
> Pump is a Franklin pump ½ hp 115VAC.  The CFs dim when the pump starts.
>
> New load will be a GRINDER PUMP FOR SEPTIC = 2HP, 15amp (240 or 120VAC –
> more than likely it will be 240V pump) – Another light dimmer!
>
> Modest daily electrical load (estimate no more than 600 WHr/day; 25AHr) –
> they are *very good* at managing their electrical use.
>
>
>
> *Solar array – to keep or replace?*
>
> 8 solar modules – a Heinz 57 mix of older modules - 2 Photowatt PMX500 (Are
> these modules UL listed?  There did not appear to be a rating label on the
> back.) wired in series, 2 Kyocera KC120-1 wired in series, 2 Golden Genesis
> PV-75 wired in series, 2 Photowatt PW 1000 12V-24V internally wired for 24V
> wired in parallel with the other modules strings – all of these modules are
> wired in 5 parallel strings for approximately 34.2Vmp and 20.4Imp, ~695W
> (STC).   Oh, and they need a new mounting structures for the modules.
>
>
>
> Should I try to work with these modules or advise the customer to start
> over (any modules that are not UL listed will have to go)?
>
>
>
> What is a good “rule of thumb” for a ratio of PV watts to battery bank
> capacity per day of autonomy?
>
>
>
> Thanks for your ideas.
>
>
>
> *Bob Clark*
>
> *SolarWind Energy Systems, LLC*
>
>
>
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