Our solar production

[RegGuheert]

SMA was stumped why turning off mains would cause this... (shouldn't be any different than a power outage. )

Actually, it is *very* different than a power outage since that often looks more like a lowering of the mains voltage (and there are protections in place to prevent overvoltage). OTOH, turning off *any* switch while current is flowing can result in extremely high voltages being produced. This is due to the inductance of the wiring in the circuit preventing the current from stopping instantaneously. The voltage that results is a function of the inductance and the rate of change of the current. If you interrupt the current at just the wrong portion of the 60Hz cycle, things like this can occur. SMA *should* be able to prevent such a failure, but it is quite difficult to design (and test) for all possible scenarios.

Teach your son to set the inverter to "Off" before switching off the mains.

 

[mikesus]

SMA was stumped why turning off mains would cause this... (shouldn't be any different than a power outage. )

Actually, it is *very* different than a power outage since that often looks more like a lowering of the mains voltage (and there are protections in place to prevent overvoltage). OTOH, turning off *any* switch while current is flowing can result in extremely high voltages being produced. This is due to the inductance of the wiring in the circuit preventing the current from stopping instantaneously. The voltage that results is a function of the inductance and the rate of change of the current. If you interrupt the current at just the wrong portion of the 60Hz cycle, things like this can occur. SMA *should* be able to prevent such a failure, but it is quite difficult to design (and test) for all possible scenarios.

Teach your son to set the inverter to "Off" before switching off the mains.

Reg - Don't have a son.

Powerboxing is when someone shuts off the mains for "kicks"

Here in AZ our panels are mounted OUTSIDE. I forgot to lock it back up after the electrician added our ChargePoint EVSE.

 

[RegGuheert]

Powerboxing is when someone shuts off the mains for "kicks"

Here in AZ our panels are mounted OUTSIDE. I forgot to lock it back up after the electrician added our ChargePoint EVSE.

O.K. Thanks for the explanation. In your case, that equates to some fairly expensive vandalism.

Thinking about it, while we do not have our main panels outside, we do have a switch on the outside that the utility requires for just the PV generation. And we are NOT allowed to lock that switch "ON", even though it is lockable. The lockability is for the utility to be able to lock it "OFF" if they decide to.

In any case, my utility tests the solar installation by throwing that switch and confirming that no AC remains on the customer side of the switch while the contacts are open. I wonder if any SMA inverters have died during such a test, since it is done while the system is generating.

With the Enphase microinverters that we have, switching off the AC is the only practical way to turn them off. There is no command (that I know of) to tell them to stop generating before switching them off for service, so I just switch them off. But when I do it, I switch them off one branch at a time (we have five separate branch circuits). This is certainly much less severe than switching the big switch on the outside of the house which turns off all the branches simultaneously. As a result, that switches much more current and it also has significantly more inductance than the branch circuits to the breakers due to an additional 250' round trip of wiring.

 

[mikesus]

Powerboxing is when someone shuts off the mains for "kicks"

Here in AZ our panels are mounted OUTSIDE. I forgot to lock it back up after the electrician added our ChargePoint EVSE.

O.K. Thanks for the explanation. In your case, that equates to some fairly expensive vandalism.

Thinking about it, while we do not have our main panels outside, we do have a switch on the outside that the utility requires for just the PV generation. And we are NOT allowed to lock that switch "ON", even though it is lockable. The lockability is for the utility to be able to lock it "OFF" if they decide to.

In any case, my utility tests the solar installation by throwing that switch and confirming that no AC remains on the customer side of the switch while the contacts are open. I wonder if any SMA inverters have died during such a test, since it is done while the system is generating.

With the Enphase microinverters that we have, switching off the AC is the only practical way to turn them off. There is no command (that I know of) to tell them to stop generating before switching them off for service, so I just switch them off. But when I do it, I switch them off one branch at a time (we have five separate branch circuits). This is certainly much less severe than switching the big switch on the outside of the house which turns off all the branches simultaneously. As a result, that switches much more current and it also has significantly more inductance than the branch circuits to the breakers due to an additional 250' round trip of wiring.

Reg - Switching off the AC is actually part of commissioning here. We did get our replacement inverter and we are back producing! With clouds we were able to produce 30kwh.

 

[JasonA]

Today is the day!! :| let's see what everyone's #'s are at the end of today!!

It gets only better from here on out!

 

[RegGuheert]

It gets only better from here on out!

Let's hope so! So far, this has been the worst month ever for our system, bar none.

 

[Nekota]

Today is the day!! :| let's see what everyone's #'s are at the end of today!!

It gets only better from here on out!

For my system this is month 24 and so far is very different from the other 23 months as having 65% of estimated output for this December compared to the 112% average from the prior 23 months. The pineapple express has brought much needed rain and with that comes overcast skies. So maybe the 112% reflects the excess of sunshine for the drought conditions and the extra rain and overcast is bringing that average down.

2014 8.522 MWh Partial Year (355 days)
2013 8.964 MWh Partial Year (357 days)


While today will be the shortest day for daylight the sun had its latest sunset on the 6 December and will have its latest sunrise on the 6 January for northern latitudes.

 

[WisJim]

The last 15 days have been the worst period of solar production since we got our first PV panels around 1981. Cause is fog and overcast weather, not the short days.

 

[JasonA]

Same here, it was totally overcast today and pretty much no sun

Today
17.7kWh
Peak Power: 4.54kW at 12:05 PM
Latest Power: 3W at 4:45 PM

Lifetime (still have 2 months since PTO)
12.5MWh

Darn clouds..

 

[dgpcolorado]

Cloudy with some midday snow showers here, but warm enough that it melted off the panels as it fell. Didn't get a chance to take a reading this afternoon before my inverters shut down, but my total production for the day should be around 0.1 to 0.2 kWh, essentially zero. I have had a few genuine zero days over the years, although they are rare.

Let's hope so! So far, this has been the worst month ever for our system, bar none.

Your comment got me to wondering about that: my worst month, by a substantial margin, was December 2010. Production the following year (2011) was more than double, the highest I've ever had for the month of December, so the month can be highly variable. This December looks to be pretty average here.

 

[RegGuheert]

December 2014 was extremely rainy and cloudy through most of the month. We had a couple of days of sunshine at the very end of the month. In spite of the addition of 29% more PV DC capability (and PVWatts predicts an extra 35% production during December due to pointing angle), the production was only 1% above the peak November production month in 2011. OTOH, with the sun we had at the end of the month, we just edged out December 2012 when figuring in the extra 29% of DC capacity (but not if you figure in the 35% difference that PVWatts predicts for this month because it includes the effect of the better pointing angle of the field array).

Below are all our numbers for 2011, 2012, 2013 and 2014 along with the PVWatts predictions for the old array (good through June 2014) and the new array (good starting with July 2014):

Month    PVW42   2011   2012   2013   2014  PVW54  Units
--------------------------------------------------------
January    916    669    869    822    857   1229   kWh
February   702    158   1085    866   1054    915   kWh
March      965      0   1350   1152   1113   1240   kWh
April     1465      0   1465   1495   1338   1899   kWh
May       1583      0   1477   1491   1457   2074   kWh 
June      1268      0   1478   1368   1521   1666   kWh
July      1448    595   1395   1406   1880   1902   kWh
August    1442   1347   1447   1333   1794   1875   kWh
September 1209    910   1295   1414   1577   1555   kWh
October   1304    931    981   1034   1258   1713   kWh
November   864    949   1041   1018   1227   1154   kWh
December   820    803    612    669    812   1108   kWh
--------------------------------------------------------
Totals   13986   6362  14495  14068  15888  18330   kWh

Since installation, our system has produced 50.813 MWh as of the end of December 2014.

Your comment got me to wondering about that: my worst month, by a substantial margin, was December 2010. Production the following year (2011) was more than double, the highest I've ever had for the month of December, so the month can be highly variable. This December looks to be pretty average here.

We turned on this system in January 2011, so we missed out on that month. Like in your case, December 2011 was, by far, the sunniest December we have seen here.

 

[dgpcolorado]

December solar production was average for the month, although it is generally the lowest production month of the year and seems to be the most variable. November and the first part of December were unseasonably warm but the last two weeks were a bit colder than average, with decent snow, although nothing out of the ordinary. The cross country skiing from my house in the piñon/juniper/oak forest is excellent at present.

Results for December for the last seven years:
                Old panels   Old+New panels
               (700 Watts)   (2170 Watts)
December 2014     68 kWh       187 kWh
December 2013     85 kWh       242 kWh
December 2012     60 kWh       163 kWh
December 2011     91 kWh
December 2010     45 kWh
December 2009     83 kWh
December 2008     62 kWh

Annual production:
2014      3217 kWh (= an average of 4.06 hours x panel wattage per day)
2013      3327 kWh (4.20 hours x panel wattage per day)
2012      1409 kWh 
2011      1203 kWh (4.71 hours x panel wattage per day)
2010      1132 kWh (4.43 hours x panel wattage per day)
2009      1165 kWh (4.56 hours x panel wattage per day)
2008       232 kWh (partial year)

 

[WisJim]

We had 21 straight days of extremely low output, to the extent that we got our first electric bill in 2 years that had charges for actual energy used (up to now we have been producing more than we use every month). The combination of charging the LEAF and overcast days resulted in an electric bill showing 11 kw-hrs of electrical use (at about 11 cents a kw-hr) for the month. The LEAF is still saving us about $70+ a month in fuel savings.

 

[BrockWI]

We also had a record low solar production in Dec (proportionally), only 125 kWh, lots of clouds. In May of 2014 we added another 1kw for 3kw total

mth 14 13 12 11 10 9
Jan 115 134 126 113 129
Feb 207 126 152 163 210
Mar 230 191 206 224 241
Apr 166 183 244 195 231
May 314 205 252 208 245
Jun 344 211 253 203 186
Jul 383 230 256 233 219
Aug 309 240 232 221 227 164
Sep 315 216 214 172 170 226
Oct 216 144 186 200 200 109
Nov 129 110 123 98 115 131
Dec 125 92 73 84 101 54

 

[SilverLeaf]

Production from my 33 230wDC SunPower Panels via Sunnyboy (SMA) 7000US Inverter (7.59kW DC)

2014 AC Production
Jan 1048
Feb 977
Mar 1347
Apr 1438
May 1476
Jun 1413
Jul 1346
Aug 1368
Sep 1242
Oct 1193
Nov 1053
Dec 844

2013 AC Production
Jan 910
Feb 1105
Mar 1328
Apr 1444
May 1474
Jun 1447
Jul 1284
Aug 1230
Sep 1280
Oct 1050
Nov 955
Dec 1005

2012 AC Production
Mar 1228
Apr 1217
May 1416
Jun 1325
Jul 1189
Aug 1168
Sep 1118
Oct 603
Nov 970
Dec 851

Link to my Solar Production - http://pvpwrev.webs.com/" onclick="window.open(this.href);return false;

 

[patrick0101]

2014 is done and I have compiled our solar production numbers and EV driving usage:

You can read the details here.

 

[nogajim]

Our first full month of production:
104 kWh

Our system is only 2.24 kW and we have some shading with the low angle of the winter sun. A friend with the same 8 panels often doubles our output. One of our pines is on the endangered list.

Anyway, we are finally in the game!

 

[seascribe]

Our 3.5kW grid-tied array (with micro inverters) is finally on line at lat. 45 degrees N in Nova Scotia, Canada. The array is vertically positioned on our shadow free, south facing wall.

The first full day of production was yesterday with the following conditions:

Sunrise to noon clear, full sun.
Noon to sunset clear, full sun to high, thin cloud layer
Temp. - 11 centigrade
Thin snow cover offering reflective radiance
Total output for day (Jan.3, 2015) 16.33kWh

 

[RegGuheert]

Our first full month of production:
104 kWh

Our system is only 2.24 kW and we have some shading with the low angle of the winter sun. A friend with the same 8 panels often doubles our output. One of our pines is on the endangered list.

Anyway, we are finally in the game!

Congratulations!

Would your friend with the same system be cracovian? If so, note that at 175 kWh he didn't quite double you for the month! His array is very well pointed for your location (34 degrees north latitude) with a tilt of 27 degrees and an azimuth of 186 degrees. If he doesn't have any shading, he should harvest 99.9% of the sunlight available with a fixed tilt array in your area. Unless your array is equally well pointed, you will have trouble keeping up with him even in months when you have no shading.

Can you please share your Enphase system link with us? TIA.

Our 3.5kW grid-tied array (with micro inverters) is finally on line at lat. 45 degrees N in Nova Scotia, Canada. The array is vertically positioned on our shadow free, south facing wall.

The first full day of production was yesterday with the following conditions:

Sunrise to noon clear, full sun.
Noon to sunset clear, full sun to high, thin cloud layer
Temp. - 11 centigrade
Thin snow cover offering reflective radiance
Total output for day (Jan.3, 2015) 16.33kWh

Congratulations! I have used vertical PV mounting around here for simple barn lighting systems since very little lighting is needed in the summertime and the most is needed at the winter solstice.

Can you also please share your Enphase system link with us?

 

[seascribe]

Congratulations! I have used vertical PV mounting around here for simple barn lighting systems since very little lighting is needed in the summertime and the most is needed at the winter solstice.

Can you also please share your Enphase system link with us?

Hi Reg. Still no link to enphase system. My contractor is away sucking back margaritas in Panama and so won't have that set up until his return. But at least for now I can monitor output on the Envoy screen. Very pleased to see that up until today the system has produced 3x the number of kWhs that my 2013 Leaf SL has used during the same period. My highest output today was around noon at 2.95kWs, not bad for a vertical mount 3.5kW system, I think.