[RE-wrenches] overfeed 7kW gridtie inverter or drop a mod per string?

[Dana]

Many times we switch to another module manufacturer as one will not
fit or another inverter manufacturer. 

PVPowered has a more relaxed window and we have had fine success with
them when SMA does not fit. 

Cold is the dictator and the 600 VDC threshold.

 

 

Thanks,  Dana Orzel

 

Great Solar Works, Inc

web - www.solarwork.com

E - dana at solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

 

"We have been slow to give up on the myth of the Earth's generosity.

Rather grandly, we have overdrawn our accounts."

Barbara Kingsolver - Water is life.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jim
MacDonald
Sent: Monday, April 19, 2010 2:37 PM
To: RE-wrenches at lists.re-wrenches.org
Subject: [RE-wrenches] overfeed 7kW gridtie inverter or drop a mod per
string?

 

For a straight grid-tie system@ 10 degree tilt, 180 azimuth,
zero/little shade, NYC avg 4.29 kWh/m²/day.

 

Feed an SMA7000 with (3) strings of 11 Suntech STP275’s [9.075 kWdc]

Or

Do strings of 10, so itd be 8.250 kWdc into the 7 kWac inverter.

 

Strings of 11= 491.7 Voc; 386 Vmp

Strings of 10= 447 Voc; 351 Vmp 

 

The tradeoff would be power clipping at/around noon in the sunny
months in the 9.075 kW scenario;

Inverter sleeping late every morning and retiring early in the
evenings in the lowered voltage scenario.

 

Trying to figure out which would yield more kWh at the end of the
year.

 

Any ideas appreciated,

thanks

 

 

 

 

Jim MacDonald

Solar Energy Systems, LLC

Brooklyn, NY 11222

www.solarEsystems.com <http://www.solaresystems.com/> 

 

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