Air Quality. [RE-wrenches]

[Lynne A Carter]

Bill,
Yes  your correct the losses from equipment is something to look at.  But I
want to know if sizing a system for the winter will also make the power
needed for the summer.  We over size systems a little most of our system
don't have grid back up nor a (willingness for) gas back up.  Giles B. For
example has no grid connection, no generator and makes plenty of power, the
rub comes with the question of air-conditioning.  So if there is a Smoggy
day the power for that air-conditioned becomes a issue.  it is not a winter
load.  I wonder if you have any information on that "Arbys" project you did
back a few years ago?  Is it still going and are there any results from the
voltage set up you did?  do you know if can it be determined is the summer
smog effecting it?  I can't remember if it was grid connected or not.  Thank
you for trying so hard to answer this question.  You are in the perfect
place to see effects of the Air Quality issue.  Do your systems now generate
100% of the power for the homes that they are installed on?  Is it a yearly
average or is it a daily reed out?  Home power is dynamic in the sense that
we use power to meet the needs of living; laundry, vacuuming, cooling and
entertaining our friends. It may be that the air Quality has nothing to do
with the out put of PV power.  It may be that the Combo of heat and smog may
be the same as heat.  Therefor sizing with a temperature compensation i.e.:
the number of 90 degree days is the most important guide for this issue.
Thank you again (my partner agrees with you, that it may not be measurable )
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: Monday, April 16, 2001 10:29 AM
Subject: RE: Air Quality. [RE-wrenches]


> Lynne,
>
> A few of the losses that I listed you dismissed too quickly. Most PV
systems
> I have worked on have wire losses above 5%. Our goal should be to keep
them
> below that but it is often difficult in the field. Living with inverter
> losses is a necessity, but not necessarily something we should accept.
There
> is a huge difference between 85% and 95% and if we don't plan for it we
are
> in trouble. Battery losses are much higher in flooded, Lead-Antimony
(L-16)
> batteries than in Lead-Calcium batteries. We can live with these but do we
> know what they are? Charge controllers are a notorious source of loss. I
am
> familiar with RV products and they show in their MPPT controller product
> manual that the unit little or no benefit for a grid-connected systems in
> hot weather. Max power tracking with battery systems is not free by any
> means.
>
> The numbers I use are real and off-grid systems have even greater losses.
> These may be numbers we don't like, but that is partly because we have
false
> concepts on how our equipment works and then we don't express our concern
to
> manufacturers to clean up their acts.
>
> Without third-party information about equipment performance, everyone is
in
> the dark until they test it for themselves. Not a very reassuring position
> to be in.
>
> Bill.
>
> > -----Original Message-----
> > From: Lynne A Carter [mailto:solarvil at netpath.net]
> > Sent: Friday, April 13, 2001 4:04 PM
> > To: RE-wrenches at topica.com
> > Subject: Air Quality. [RE-wrenches]
> >
> >
> > Hi I did not get an ok on sending an (Jpeg) attachment if you want to
see
> > the pollen and Grey sky send me personal email I will send copy for
those
> > interested.
> > Bill,
> > You made a good list I agree theses things can effect the power
production
> > of the PV array and/or the whole system.  We have a customer that
> > is willing
> > to test the Uni-solar Laminates. The pollen count is high the
> > past few days
> > everything here is that yellowey-green dust from the loblollies.
> > So yes I do
> > have dirty PVs to day.  NO rain so far but the temperature is going down
a
> > little. I have attached some Jpeg photos as examples
> > Your list in relation to our systems here in the east.
> > Shading. Not much of an issue for us good solar access on systems. The
air
> > is the question. Dirt. Maybe so, dirt in the air could stick to the
array
> > looks as if that is
> > what is happing today.  Wire Losses. not more than 2% - 5% Module
> > Mismatch.
> > not here Inverter Losses (much higher than most people predict)..
> > I can deal
> > with that.  Battery Losses. I can deal with that.
> > Charge controller losses.  Have you check out the RV power products
> > recently?
> > NC recent reports have us in the orange zone and the red zone for most
of
> > the summer. We are 6th in the nation for smog depending the report
> > www.epa.gov.
> > You said >Our diffuse (scattered) radiation can be 30% of the
> > energy we get
> > from the sun. This also makes tracking systems a little less effective.
<
> > I disagree on the tracker issue. However, I am off-grid and when the
array
> > follows the sun every day, I have made more power. I simply get a
> > more power
> > form tracking arrays with a smaller footprint.  Besides, they are sexy
as
> > hell.  In the morning, I am making power sooner.  During cloudy
> > days, it is
> > great to be at a maximum power (optimal tilt) when the sun appears for
an
> > hour of the day.  Maybe it just feels good. What do you mean by
effective?
> >
> > So could do an example of this? Take the STC rating and multiply
> > by 0.7 and
> > that is a fair number for system with a STC > 1
> > max AC power (spring and fall). Take STC rating (in kW) x 0.6 x solar
> > resource (5.0 kWh/m2/day--Raleigh, NC) x 365 days/year = Annual Energy
> > I am not getting numbers I like.
> >
> > Lyn
> > PS I did find out that Most air quality databases are about two years
> > behind.
> >
> >
> > 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
> >
> >
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