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9,500 kWh of production in first year - Page 9

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Posted by Bob on May 12, 2008, 8:07 pm
Bob wrote:

that "warmup" power is already included in the efficiency spec of the
inverter - don't double-count it. If you really care about the losses in
the inverter, you could measure its current draw with an AC clamp-on
probe at night to see the standby load. That draw should be pretty
constant through the night.

My inverter readout shows it's already generating over 50 watts before
the sun is even up (pre-dawn sky glow), so be sure to take your readings
when it's really dark.

** Posted from http://www.teranews.com  **

Posted by Robert on May 12, 2008, 9:51 pm

50 watts before sunrise?  How many kW is your system?  I would also
like to know your location and kWh/yr per kW system.
Here is one of the two sites I am tracking data from:
It is monitored by fatspaniel.   Click on a time period, data
irradiance and PV output, and Download Data, and you will get 15
minute readouts.
Sunrise today, 6 A.M.  This 12 kW STC system with the panels oriented
180 degrees shows irradiance before 6 A.M., but no output today until
6:45 A.M., at which time the irradiance was 113 W/m2.  The other very
noticeable number is the output of about -290 Watts at night (standby
tare loss for the inverter used according to the specs should be less
than 30 W).  I sent an email to fatspaniel about this last year and
got the response I quoted in my post of 5/10 about the inverter
consuming electricity.
This is just one system, which is a reason I am interested in info
from other systems, and data from a separate meter.

Posted by Bob on May 13, 2008, 11:55 pm
 Robert wrote:

whoops. My bad. I checked last night and this morning - My 3kW (peak at
the panel) system is putting out 50W 15 minutes *after* astronomical
sunrise and 15 minutes *before* sunset. I don't have an independent
meter to see the inverter standby power.

Other stats on my system: 2 arrays in parallel; elevations are both 66
degrees; half (1.5kW) at azimuth 240, half at 150. It's only been
running for a couple of weeks. The daily energy output (AC IIRC) has
been a consistent 19 to 20kWhr. It's a Fronius inverter.


** Posted from http://www.teranews.com  **

Posted by Robert on May 14, 2008, 2:19 am


Solar panel elevation 66 degrees?  Are you at 66 degrees N latitude?
If so, very good AC output, but the sun is up almost all day!  Or
maybe you are at a higher latitude and are decreasing the panel
elevation this month :)   Do you have a setup so that you can track
the midnight sun?  What is your longitude?  Is this too many


Posted by Solar Flare on May 14, 2008, 2:50 pm
 The tracker keeps twisting the cables up in the winter.

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