[RE-wrenches] P1 micro performance

[Bill Brooks]

Just to beat a dead horse and provide additional screen captures, take a
look at what is below. "Clipping" is completely the wrong word in this
context. It is simply operating at a higher dc voltage on the I-V (not max
power). The power quality requirements do not allow systems operating on the
utility system to modify their sine wave like many battery-based inverters
do under heavy loading conditions. Below are graphs from yesterday's power
output. See how when it hits max power of the inverter, the dc voltage
rises. Nice case in point. Also notice that the TL inverter out-produces the
non-TL inverter (because of higher efficiency) until max power is reached.
At max power, both are the same.

 



3949 Joslin Inverter Comparison


 


cid:6e44facdc93e428095496b438cd56941


cid:c2f51ce2d7bf493f9c2af46706cf6c66

3/22/2013 10:38:36 AM (UTC) Created by Sunny Portal / SMA Solar Technology
AG 

 

 

Bill.

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of David
Brearley
Sent: Friday, March 22, 2013 8:11 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] P1 micro performance

 

The power quality should not be adversely affected. 

 

While I'm sure different manufacturers may limit power in different ways, in
theory all the inverter is doing is moving the array off its MPP. Here's a
description from AE:

 

If the power available from the array exceeds the nameplate rating of the
inverter, the inverter will limit 

the power and current coming from the array to the inverter's maximum
nameplate power and 

current rating. The inverter does this by reducing the DC input current,
which causes the DC 

operating voltage to rise above the maximum power point of the array,
thereby 'clipping' the 

array output. This effectively limits the output of the array without
stressing the inverter.

 

http://solarenergy.advanced-energy.com/upload/File/Application%20Notes/DCLoa
dingOfPVPinverters.55-600100-75-A.pdf

 

On Mar 22, 2013, at 9:52 AM, William Dorsett wrote:





OK, if the upper limit if the curve is "flat topped" do we get increased
problems with harmonic noise at the knee as you would in modified "square"
wave?

 

Bill Dorsett

Manhattan, KS 

 

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