Air Quality. [RE-wrenches]

[Bill Brooks]

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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