Our solar production

[wsbca]

Can someone explain to me (or point me to something as I can't seem to find anything online) how power is sent back into the grid?

This thread, while not 'documentation', asserts an answer:

http://forums.whirlpool.net.au/archive/1835296

(and then devolves into bickering over details and implications....sort of like we do here sometimes

 

[turbo2ltr]

Perfect, thanks!

 

[Weatherman]

To me the only way to reverse current flow is to increase the voltage over the incoming grid power. But that sounds like a bad idea, and I have yet to find any documentation that actually says that. I'll admit my knowledge on AC theory is a bit limited.

I thought that was how it works. Incoming power from the solar array increases the voltage ever so slightly, just enough to cause electrons to flow out to the grid rather than flowing in.

It's kind of like when you suddenly turn on a huge consumer of electricity (like your A/C) in your house and your lights dim for an instant. It's a voltage drop which inspires more electrons to flow in from the grid to reestablish the balance.

 

[turbo2ltr]

That link cleared it up for me. It makes more sense when you look at the inverter as a current source. The grid is essentially an infinite load beyond the current grid voltage as compared to the power you are putting in. So slightly adjusting the voltage above the incoming can create lots of current flow...

 

[RegGuheert]

The grid is essentially an infinite load beyond the current grid voltage as compared to the power you are putting in.

That is certainly true, but there is a non-zero impedance between your array and the power grid. As a result, there is a non-trivial voltage rise that must occur within your inverters in order to feed power back to the grid. If your service tends to sit near the upper end of the grid voltage range like ours does, then your inverters are almost certainly operating above the 250VAC maximum for North America. Some microinverters operate above 260VAC.

For reference, we recently had some discussion about the voltage drops seen in our system in this thread: Our LEAF disrupts our PV system while charging at L2.

 

[Weatherman]

I didn't know that the Enphase microinverters recorded things like AC voltage, temperature, DC Voltage and DC current along with power produced. That's pretty neat.

Looks like the final inverters in my two strings ramp up the AC voltage to about 250VAC at their peak power production time (above the 240VAC minimum). I can also see why I got clipping last Monday for the first time since the panels were installed back in June. The panel temperature was in the 90s (air temp was in the 60s with a strong northwest wind). 120F or higher is much more common in the middle of the day.

 

[RegGuheert]

A good month! November 2012 production beat November 2011 by 92 kWh or almost 10%. It even topped October 2012 by 6%!

I'm really starting to think that when they updated the firmware in our microinverters in February (when the misbehaving unit was replaced) they may have improved energy harvest. It's hard to know...

Here are our numbers so far this year:

• Jan 2012: 0869 kWh
  Feb 2012: 1085 kWh
  Mar 2012: 1351 kWh
  Apr 2012: 1465 kWh
  May 2012: 1478 kWh
  Jun 2012: 1478 kWh
  Jul 2012: 1396 kWh
  Aug 2012: 1447 kWh
  Sep 2012: 1294 kWh
  Oct 2012: 0981 kWh
  Nov 2012: 1041 kWh
  -------------------------
  2012 Tot: 13885 kWh

 

[Weatherman]

An unusually cool, dry and sunny November meant way above expected production for the month.

7.2 kW system installed at the end of June 2012:

July: Expected: 913; Actual: 965 (1.038 kWh per panel per day)
August: Expected: 895; Actual: 898 (0.966 kWh per panel per day)
September: Expected: 873; Actual: 852 (0.947 kWh per panel per day)
October: Expected 866; Actual: 924 (0.994 kWh per panel per day)
November: Expected 752; Actual: 920 (1.022 kWh per panel per day)

December: Expected 750
January: Expected 838
February: Expected 837
March: Expected 945
April: Expected 1037
May: Expected 970
June: Expected 891

Total Expected for Year: 10,567 kWh or 0.965 kWh per panel per day (solar radiation 5.25 kWh/m2/day)

 

[TonyWilliams]

...Date......Monthly....Year to Date....Daily Peak

Jan 2012: 937 kWh..... 937 kWh..... 39.79 kWh
Feb 2012: 970 kWh....1910 kWh.... 43.57 kWh
Mar 2012: 1210 kWh.. 3120 kWh... 50.72 kWh
Apr 2012: 1267 kWh.. 4380 kWh... 54.18 kWh
May 2012: 1390 kWh.. 5770 kWh... 53.6 kWh
Jun 2012: 1455 kWh.. 7230 kWh... 55.1 kWh
July 2012: 1402 kWh.. 8632 kWh... 52.4 kWh
Aug 2012: 1318 kWh.. 9951 kWh... 50.0 kWh

http://enlighten.enphaseenergy.com/public/systems/Ukwf22392" onclick="window.open(this.href);return false;

September 2012 Total: 1.25 MWh
October 2012 Total: 1.12 MWh
November 2012 Total: 0.91 MWh
December 2012 Total: 0.716 MWh

2012 Year to Date: 13.9 MWh


January 2013 Total: 0.955 MWh
February 2013 Total: 0.999 MWh


Lifetime: 19.9 MWh



Estimated Production

Month Solar Radiation
(kWh/m²/day) AC Energy (kWh)
January 4.1 913.0
February 4.7 937.0
March 5.41 1191.0
April 6.08 1276.0
May 6.49 1400.0
June 6.67 1376.0
July 6.74 1403.0
August 6.57 1356.0
Sept 6.01 1213.0
October 4.99 1072.0
Nov 4.45 946.0
Dec 3.78 839.0

 

[SilverLeaf]

Nov. 2012 - 971.048 kWh A/C (1,029.1 D/C) :mrgreen: from my 6.9 kW Sunpower PV Array

 

[dgpcolorado]

My November production for my old panels was up 12% over last November and 7% higher than the previous high, November 2009, over the five years I have been tracking it:

Nov '08 74 kWh
Nov '09 98 kWh
Nov '10 83 kWh
Nov '11 94 kWh
Nov '12 105 kWh

Overall, my November total production was 293 kWh, a bit more than my estimated total household/car usage of 281 kWh for the month. It was the sunniest, driest, warmest November that I can remember here. We sure could use some snow!

 

[davewill]

9.1kW DC - 28 SunPower 327w panels

Energy Production: 
Aug 01, 2012 - Aug 31, 2012 1,468.97 kWh
Sep 01, 2012 - Sep 30, 2012 1,348.08 kWh 
Oct 01, 2012 - Oct 31, 2012 1,206.23 kWh 
Nov 01, 2012 - Nov 30, 2012   968.34 kWh 
Lifetime (Mid-Jul 2012) 6,045.01 kWh

 

[Cheezmo]

I don't have all the fancy graphs and things going yet.

After 5 days, 107 kWh on my 6kW (24 panel) system. There have been a few cloudy days (mornings especially). Got 30kWh one day.

Can't wait for those long summer days.

 

[RegGuheert]

After 5 days, 107 kWh on my 6kW (24 panel) system. There have been a few cloudy days (mornings especially). Got 30kWh one day.

Congratulations! It feels good, doesn't it?

Can't wait for those long summer days.

Our peak days do not occur in the summer, but rather they happen in the springtime. This is because the panels are cooler and even though the days are shorter the sun goes much closer to the boresight of the array than it does during the summer.

 

[hill]

Once we hit around mid November, we stop over-production. Even in So Cal, we're in the shortest 40 days of the year now. So in addition to being rainy/cloudy/sunless days - we run more lights due to longer darkness. Unlike summer where we run as high as 20+kWh surplus - we now end up short - and average electricity use is almost 10kWh daily from the grid. That's after switching all the holiday lights over to LED's too. Yuck No complaints though. We still have about $35 on SCE's books for over generation. But still, I do love me some long summer days.

 

[Viktor]

Overall, my November total production was 293 kWh, a bit more than my estimated total household/car usage of 281 kWh for the month. It was the sunniest, driest, warmest November that I can remember here. We sure could use some snow!

Are you happy now? Look like mountains getting some snow

 

[lwaz12a]

Our setup:

We went live on 12/4/2011 with 84 Canadian Solar CS6P230P - 230w solar panels, totaling 19.32 kW with 84 Enphase M215 grid tied micro-inverters. With net metering, we settle with the utility annually (I think our settlement was last April). Now that we have a full year under our belt and lots of credits stored up from the summer, it looks like we'll have $8.72 bills each month. From what I can gather, we're generating slightly more energy than spec. Pleased with the setup with a minor exception that the enphase/enlighten web connection goes dark from time to time.

Icing on the cake would be if the market for Pennsylvania SRECs would be a bit stronger, but our State Reps and Governor are enamored with the utility companies who are lobbying against maintaining or expanding the current program and believe fracking the Marcellus is the answer to everything.

Best to all.

 

[dgpcolorado]

Overall, my November total production was 293 kWh, a bit more than my estimated total household/car usage of 281 kWh for the month. It was the sunniest, driest, warmest November that I can remember here. We sure could use some snow!

Are you happy now? Look like mountains getting some snow

No, I only got an inch and a half from that last storm; it mostly hit the south side of the San Juan Mountains. More is expected tonight and tomorrow but I'll be surprised if I have enough to ski on at my house. Even Red Mountain Pass is only at 58% of average snowpack:
ftp://ftp.wcc.nrcs.usda.gov/data/snow/update/co.txt" onclick="window.open(this.href);return false;

 

[Weatherman]

December (especially the first half) was cloudy, warm and humid, and this really cut into solar production for the month. But, in spite of the clouds, production was still above the "expected" value. I'm impressed with how little seasonal variation there is in output.


7.2 kW system installed at the end of June 2012:

July: Expected: 913; Actual: 965 (1.038 kWh per panel per day)
August: Expected: 895; Actual: 898 (0.966 kWh per panel per day)
September: Expected: 873; Actual: 852 (0.947 kWh per panel per day)
October: Expected: 866; Actual: 924 (0.994 kWh per panel per day)
November: Expected: 752; Actual: 920 (1.022 kWh per panel per day)
December: Expected: 750; Actual: 822 (0.884 kWh per panel per day)

January: Expected 838
February: Expected 837
March: Expected 945
April: Expected 1037
May: Expected 970
June: Expected 891

Total Expected for Year: 10,567 kWh or 0.965 kWh per panel per day (solar radiation 5.25 kWh/m2/day)

 

[RegGuheert]

Well, December was a pretty poor solar month to end an outstanding year. I think this was our lowest production month to date.

Here are all our numbers for 2012:

• Jan 2012: 0869 kWh
  Feb 2012: 1085 kWh
  Mar 2012: 1351 kWh
  Apr 2012: 1465 kWh
  May 2012: 1478 kWh
  Jun 2012: 1478 kWh
  Jul 2012: 1396 kWh
  Aug 2012: 1447 kWh
  Sep 2012: 1294 kWh
  Oct 2012: 0981 kWh
  Nov 2012: 1041 kWh
  Dec 2012: 0612 kWh
  -------------------------
  2012 Tot: 14497 kWh