Honestly, William, in these type of cases I usually walk away from the job if the customer isn't willing to reduce where possible. There is no such thing as a completely fool proof off grid PV system. Like a good lawyer, the best way to have a stellar record is to know which cases to take....just one man's opinion of course, but we get approached for many systems like this, particularly in the Caribbean and I have learned that there is such a thing as a good solar customer and also a bad solar customer.
Daryl > Hi William, > In off grid applications, you want to have sufficient RE to keep up with > load demand > and only run the generator when RE cannot keep up. However, having too > much RE is a waste because it will > result in energy not harvested (if regulating), however, diversion > controllers can allow the excess energy to be utilized > (i.e. water heating). > Running the gen up to the bulk level replaces approx 80% of capacity, and > maximizes fuel consumption, allowing RE to get the > batteries charged the last 20%. Automatic gen start capability with > staggered start voltages allow you to target 50% discharge > more accurately, and minimizes user interaction. Try to calculate the > total daily kWhrs and match the demand with RE as > closely as possible. > Hope that helps, > Rgds, > _____________________________________________________________________________________ > > > Eric Bentsen | Schneider Electric | Solar Business | UNITED > STATES | Technical Support Representative > Phone: +(650) 351-8237 ext. 001# | > Email: eric.bent...@schneider-electric.com | Site: > www.schneider-electric.com/solar | Address: 250 South Vasco Rd., > Livermore, CA 94551 > > > *** Please consider the environment before printing this e-mail > > > > > From: > Jay Peltz <j...@asis.com> > To: > RE-wrenches <re-wrenches@lists.re-wrenches.org> > Date: > 08/16/2013 02:01 PM > Subject: > Re: [RE-wrenches] PV Assist > Sent by: > re-wrenches-boun...@lists.re-wrenches.org > > > > Hi William > > Thx helps a lot. > I can only say how I do it. > I'll give the client some options, including the change of appliances and > usually the price difference makes the sale one way or the other. > > Funny reminds me of the old days, only with much smaller loads/$. > > Good luck > > Jay > > > > Sent from my iPhone > > On Aug 16, 2013, at 12:49 PM, "William Miller" <will...@millersolar.com> > wrote: > > Jay: > > There are four systems in question. In three the loads are year round and > one is summer only AC loads. The year round loaded systems have loads day > and night. > > One is a highway maintenence station with at least 4 residences. > One is a family compound with two homes with electric ranges, water > heaters, AC units (I know its stupid, lord knows I've tried to convince > them to change appliances.) > One is an animal rescue operation with heater loads. > One is a large home with 5 very small, very new, very sophisticated and > frugal AC units > > I know it is silly to move these loads off-grid, but people do it and they > will hire someone to work on the systems. It may as well be me, doing the > best I can to use the resources as wisely as possible. > > William > > PS: It always happens like this: I get a call from a client with > problems. Well, of course their expensive battery bank died and it died > because of wasteful appliances. The prescription is a new, expensive > battery bank and, at the same time, new, expensive, efficient appliances. > They complain can't afford both and they have to have the batteries, so > that is what they get. Repeat every two years. Sad.... > > Wm > > > From: re-wrenches-boun...@lists.re-wrenches.org [ > mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jay Peltz > Sent: Friday, August 16, 2013 12:22 PM > To: RE-wrenches > Subject: Re: [RE-wrenches] PV Assist > > Hi William > > I feel it's impossible to discuss without more specifics. > > For example if the extreme loads are only every ( just run the genny) so > often vs seasonal ( maybe AC coupling makes more sense vs cycling a > extremely expensive battery 4 x day), vs year round vs what is do able > etc > > I would be curious to know what some of the parameters are, as I'm sure > others as well > > Jay > > Peltz power. > > > > > > Sent from my iPhone > > On Aug 16, 2013, at 10:53 AM, "William Miller" <will...@millersolar.com> > wrote: > > Friends: > > We have been receiving a flurry of requests for design of off-grid systems > where the loads are enormous, relative to normal off-grid requirements. It > is obvious that the size of PV and battery arrays to power these loads is > beyond what is practical. We have dubbed these systems Generator/battery > with PV assist, or PV assist for short. > > These systems will cycle batteries multiple times per day. It is my > understanding that the extra battery cycels will shorten battery life. > Since generator run is expected, we are willing to increase generator run > time in order to prolong battery life. > > The parameters I suggest are an aggressive load start and a very high > battery start parameter. This will prevent deep discharge of the battery > bank. I know shallow discharge is not the norm, but I don't believe > shallow cycling is a problem as long is it as at the top of the voltage > window, i.e. the batteries achieve absorption at least once per day. > > We know a load start ciuld result in an abbreviated run time, curtailing > absorption period, but we are assuming there will be a battery votage > start at least once per day allowing full absorption. > > Has anyone else considered these issues, and what conclusions did you make > > I am looking forward to a spirited discussion as usual. I > throuroughlyenjoy and beneift from them, even thought the advice is > usually conflilcting. Thanks in advance. > > William Miller > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > ______________________________________________________________________ > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
