[ausev] Residental Solar Power

[Brian Lasseter]

On Sun, Aug 10, 2008 at 11:43 PM, Dustin <ullearn at gmail.com> wrote:
> What are some real annual #'s you are seeing from your system?  What is the
> peak max of your panels (125-210w)?  I am being told that a 3kw system can
> produce anywhere from 4,490 - 6000 kWh per year; is this true?  For
> calculation purposes how much average sunlight a day should I calculate
> with?

Since you ask... I have 32x 208W panels in mounted in 4 parallel
strings, generating 228VDC at 7.3A max per string, for a total of 6656
watts of solar.  They are 12.8% efficient Sharp ND-208U1 solar panels.

I honestly do not have exact numbers for how many kwh per year I have
generated, since I did not pay the extra $300 for hardware to log
data.  :-/  Also, the solar panel meter does not show up on my
electric bill, only the net electrical usage shows up on my bill.

However, when I go and look at the solar panel meter (which solely
measures panel output, and started at 0), I'm reading about 9000kwh
right now.  I installed the first 3328W 16 months ago, and the second
3328W 8 months ago.  That's 24 months or 2 years of equivalent usage
of a 3kw panel to generate 9000kwh... so that's about in line with the
low end of your scale... I'll try to remember to check my meter on
Sept 6th... which would be exactly 2 years of usage since the panels
were installed on Apr 6th '07 and Jan 6th '08.   I suspect that
6000kwh per year would be for a tracking solar installation.  My
panels do not move.

4500kwh per year also lines up with the monthly numbers quoted to me
when I got the system installed:
3.328 kW Solar Electric System Estimated Output - Lasseter Residence -
21° Pitch and 220° Azimuth
Jan - 275kwh
Feb - 310kwh
Mar - 390kwh
Apr - 375kwh
May - 420kwh
Jun - 430kwh
Jul - 455kwh
Aug - 435kwh
Sep - 375kwh
Oct - 365kwh
Nov - 275kwh
Dec - 260kwh

> I am seeing it range for Austin from 4.4 hours to 5.2 hours (the company
> that is quoting me says 5.2 is conservative).

I do not have an answer for you year... my installers calculated this
for me.  However, I see my solar panels generating power from sunup to
sundown.  Granted... it's only like 300W of power for the first and
last hours of the day.


> The quote I just received shows about $7k for 3kw system and $13.5k for 6kw
> system.  I am tempted by the 6kw system b/c I could netzero for some months
> and bring my yearly cost down by almost 70% (per the quote).  This would
> make my ROI period, based on current energy rates, 15 - 10 years; this is
> all dependent on what real power is generated.  What else am I missing?

The prices you are quoting make me think that the 6kw system is going
to be installed over two years.  Austin will only rebate
3kw/person/year.  So I'd only install 3kw per city year (which is
Oct-Sep.), and Uncle Sam gives you $2k in Federal Income tax rebates
which only applies if you install the panels during the tax year
(which is Jan-Dec.)  I went with the 6kw system since I knew that my
electric car would be pulling an extra 150kwh per month.


> Though I am still on the fence about purchasing due to the uncertainty of
> how much per year I could really generate.

Honestly... how much you can generate is readily calculable from your
solar panel attributes, lattitude, longitude, the solar panel's angle
to the horizon, and the solar panel's angle from south.  Any of the
installers should be able to provide that information.


-- 
TTFN,
Brian "Lasso" Lasseter

"No Sane man will dance." -Cicero (106-43 B.C.)