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wsbca
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Re: Why I'm not generating full capacity?

Mon Nov 24, 2014 5:43 pm

RegGuheert wrote:
wongfeihong187 wrote:Good to know that I'll get at least close to 5.4kw during the summer.
You will be farthest from 5.4kW during the summer unless your roof is VERY flat. You will never get much beyond 5.0kW, which is the point at which your inverter will limit the output.
This prediction seems a little misleading to me - though his inverter will indeed likely clip at some point in the middle of the day in summer months (unless it's hot), his total daily production will definitely be highest in those months, which is what I think he's really concerned about. And unless his orientation is really odd, his peak instantaneous production will be lower in the winter as well. For example, our fairly steeply angled roof faces WSW - right now our peak is about 2400w at best orientation on a 3.44kWDC/3kWAC rated system. In the summer we are right up close to the rating in steady state (and clipping when intermittent clouds cause temperature swings).

Maybe all you are saying is that his 5KW inverter will always clip at ~5100w, which it will, but I'm confused by the "farthest from 5.4 during summer" statement.
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cracovian
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Re: Why I'm not generating full capacity?

Mon Nov 24, 2014 8:09 pm

Here's a good link that explains how steeper tilts (mostly) peak in the colder months: http://solarpaneltilt.com" onclick="window.open(this.href);return false;
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WisJim
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Re: Why I'm not generating full capacity?

Sun Nov 30, 2014 5:50 pm

I frequently get more than rated output from my grid-tied array (2.46kw with Enphase microinverters). Usually it happens in March, but I also exceeded 2 1/2 kw peak a couple of times in the last month which was a surprise to me.

wongfeihong187
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Re: Why I'm not generating full capacity?

Mon Jan 05, 2015 2:36 pm

Hello all, still not producing anywhere where I should be (5.4 kw). Here's a snap shot of my system, taken at 1:30pm on a cloudless day:

PV System Overview | Chu's Household

PV System Data
Current power
3399 W Energy and Power »
Current PV system status


PV System Logbook »
Energy
6035 Wh
Today Total: 975.74 kWh

CO2 avoided
9.3 lb
Today Total: 15 cwt

PV system information
PV system power:
5300 Wp
Commissioning:
11/30/2014 PV system profile »
Weather for San Diego
62 °F
Cloudless Tomorrow »

Location
92127 San Diego
UNITED STATES
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RegGuheert
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Re: Why I'm not generating full capacity?

Mon Jan 05, 2015 2:59 pm

wongfeihong187 wrote:Hello all, still not producing anywhere where I should be (5.4 kw).
As I've stated previously, your system will NEVER produce 5400W and should only ever get just above 5.0 kW peak. If you expect to EVER see 5.4 kW from a system containing 5.3 kWp of PV connected to an inverter with a 5.0 kW peak output you are setting yourself up for disappointment.

For reference, I have a 12.5 kWp system which can never produce more than about 11.0 kW due to the limitation of the inverters. Even then it can only happen during certain times of the year. I have never seen more than 10.9 kW.

Since you are now closer to the winter solstice than you were when you first posted in November, it is not surprising that your peak production is lower today than on November 24.

But since you will not tell us how steep your roof is, we cannot tell you if the change is reasonable or not.
RegGuheert
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wsbca
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Re: Why I'm not generating full capacity?

Mon Jan 05, 2015 4:30 pm

wongfeihong187 wrote:Hello all, still not producing anywhere where I should be (5.4 kw). Here's a snap shot of my system, taken at 1:30pm on a cloudless day:

PV System Overview | Chu's Household

PV System Data
Current power 3399 W Energy and Power »
It's the dead of winter - sun angle is too low. As a point of reference, my 3.4kwDC rated (2.99AC, 3kw inverter) panels, which face WSW at a fairly typical roof angle topped out at a lowly 2200 W today, also in San Diego. Pretty similar percentage to what you are seeing. In May-June, unless it's really hot, I'll be making 3060 at midday (at which level the inverter will be clipping).

To put it another way, right now I'm making between 12 and 13 kwH total on a clear day. On optimal days in the late spring I will make 23 or more.

The sunlight has to be coming in nearly perpendicular to your panels for them to operate at their rating. When that will most nearly happen depends on exactly which way your array points, and at what angle, but your installer hopefully oriented the array for the best overall (year around) performance given the limitations of your roof. That means it won't be at its maximum during these shorter days (if it was, you'd be giving up more total production during longer days). Be patient.

Your annual production is going to end up looking something like this:

Image
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WisJim
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Re: Why I'm not generating full capacity?

Wed Jan 07, 2015 4:17 pm

I really like my microinverters. I have an array of 12 panels each rated at 205 watts, using 215 watt Enphase microinverters. The panels are ground mounted on an adjustable tilt mount. Today the high outside temp in the shade by the garage reached minus 6 degrees F. My panels put out 225 watts each for over 3 hours--the 215 watt Enphases clip at 225 watts.
BUT I am sure that my low temperature here had a lot to do with it. I don't think you willl ever get that kind of low temp boost in energy output in California! And my adjustable tilt makes a difference, too, but not as much as those low temps and the reflective snow on the ground.

knightmb
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Re: Why I'm not generating full capacity?

Fri Jan 16, 2015 6:14 pm

wongfeihong187 wrote:Hello all. New to solar so this may be a dumb question. I finally got my LG 300's installed last week and am finally producing my own electricity! Question, my system is rated to be 5.4kwh but I'm finding that at peak times of the day I'm only generating 4.3 kwh? why is this? Thanks for all you solar gurus who know this stuff :)
There are a few variables, time of year for one. This time of year my solar array is only about 80% efficient against rated maximum. You are getting pratically the same efficiency as me, so you are actually doing quite well.

The other is wiring of the panels and charger controllers. The closer the charger controller is to your battery/inverter, the better. It helps to keep the line voltage from the panels high before it is step down for use. If your charger controller is too close to your panels and the source draw is far away, you lose a lot of wasted energy in the form of low heat. Without a lot of details about your setup, I am just kind of guessing at some common reasons for you.
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