[RE-wrenches] PV Assist

Fri Aug 16 17:26:00 PDT 2013

I find its also about the money.  If they're expecting a $20k system to 
perform like a $100k one, then yes, move on.  I agree with Daryl that 
you keep a good record by picking your clients.
On the other hand, I have some fairly wealthy customers that don't want 
to reduce their loads, and are willing to pay for it both in PV and 
fuel.  They've been excellent long term customers, so I'm not about to 
be as cavalier as others here and say walk away.
I currently have a very energy minded customer that wants an electric 
stove and water heater, because she doesn't want to use any fossil fuels 
on site.  If the customer wants a mega system and is willing to pay for 
it, why is it our business to judge them?

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 8/16/2013 4:22 PM, penobscotsolar at midmaine.com wrote:
> 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.bentsen at 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
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>>
>>
>>
>> From:
>> Jay Peltz <jay at asis.com>
>> To:
>> RE-wrenches <re-wrenches at lists.re-wrenches.org>
>> Date:
>> 08/16/2013 02:01 PM
>> Subject:
>> Re: [RE-wrenches] PV Assist
>> Sent by:
>> re-wrenches-bounces at 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" <william at 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-bounces at lists.re-wrenches.org [
>> mailto:re-wrenches-bounces at 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" <william at 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
>>
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