Fun output comparison (SolarWorld + SolarEdge) vs (Canadian Solar + Enphase)

[dust999]

My solar system has been up and running since November last year and I've been comparing the output of my system to another install 6 miles from my house. I'm running SolarWorld + SolarEdge, the other install is Canadian Solar + EnPhase. The two systems are virtually identical in terms of rated output. Both sites have no shading issues other than snow coverage effects in winter.

The Canadian Solar system has produced, on average, 6% more year to date than my SolarWorld system. It's a fun/un-scientific comparison, we are 6 miles apart so the weather variables influencing output are somewhat different, but it would suggest that the CS + EnPhase combination produces more than my SW + SE combination. = potential buyers remorse on my side....

My specs:

31 x 280W SolarWorld Black Mono
1 x SolarEdge 7600 inverter
31 x P300 SolarEdge optimizers

Output = 8,680W

Azimuth = 154


"Competition" specs:

The info I'm getting for this install is off the public EnPhase portal which does not show all the specs.

34 x CS6P-255P Canadian Solar
34 x EnPhase micro inverters, unknown model

Output = 8670W

Azimuth = 167

[ButchDeal]

My solar system has been up and running since November last year and I've been comparing the output of my system to another install 6 miles from my house. I'm running SolarWorld + SolarEdge, the other install is Canadian Solar + EnPhase. The two systems are virtually identical in terms of rated output. Both sites have no shading issues other than snow coverage effects in winter.

The Canadian Solar system has produced, on average, 6% more year to date than my SolarWorld system. It's a fun/un-scientific comparison, we are 6 miles apart so the weather variables influencing output are somewhat different, but it would suggest that the CS + EnPhase combination produces more than my SW + SE combination. = potential buyers remorse on my side....

My specs:

31 x 280W SolarWorld Black Mono
1 x SolarEdge 7600 inverter
31 x P300 SolarEdge optimizers

Output = 8,680W

Azimuth = 154


"Competition" specs:

The info I'm getting for this install is off the public EnPhase portal which does not show all the specs.

34 x CS6P-255P Canadian Solar
34 x EnPhase micro inverters, unknown model

Output = 8670W

Azimuth = 167

The enphase one is closer to south facing than yours ( 13 degrees).
Are there any shadows on the two sites?


Also your nomenclature of rated output is inaccurate, that is the rated STC DC size of the system, not the rated output.

[J.P.M.]

Fun yes, conclusive, probably not so much.

Too many variables can influence estimated output to be able to call a 6% difference significant, starting with the accuracy, and the differences in the accuracy, of the recording/reporting equipment.

Anyway, 6% is not that much of a difference. BTW, What's the tilt of the two arrays. That will influence output some as well, more so in winter. Also, what does PV Watts give as an estimate for each system for the period Nov - April ?

[dust999]

The enphase one is closer to south facing than yours ( 13 degrees).
Are there any shadows on the two sites?


Also your nomenclature of rated output is inaccurate, that is the rated STC DC size of the system, not the rated output.

Sites are shadow free other than snow accumulation.

[randomuser]

Also, what does PV Watts give as an estimate for each system for the period Nov - April ?

How granular is PV Watts? I just entered my current address and the address of my former residence. Google maps driving directions says it's 6.8 miles between the 2 houses, so I'm guessing it's about 6 miles as a bird flies? I used the same parameters for both addresses and PV Watts shows the same electricity generation output.

[ButchDeal]

How granular is PV Watts? I just entered my current address and the address of my former residence. Google maps driving directions says it's 6.8 miles between the 2 houses, so I'm guessing it's about 6 miles as a bird flies? I used the same parameters for both addresses and PV Watts shows the same electricity generation output.

does the location 6 miles away have some indication that it should have DIFFERENT generation? is it maybe 6 miles vertical away?

It is possible for there to be a generation difference in such short distances but PVWatts uses TMY data for weather, and it just doesn't have that resolution.

Also PVWatts does not take into account local geography, like proximity to mountains...


Most differences are due to location specifics like tilt, azimuth, shadows, followed by equipment differences (including measuring equipment).

[dust999]

Fun yes, conclusive, probably not so much.

Too many variables can influence estimated output to be able to call a 6% difference significant, starting with the accuracy, and the differences in the accuracy, of the recording/reporting equipment.

Anyway, 6% is not that much of a difference. BTW, What's the tilt of the two arrays. That will influence output some as well, more so in winter. Also, what does PV Watts give as an estimate for each system for the period Nov - April ?

My inverter is the revenue grade model used for SREC reporting. No idea on the EnPhase setup.

Do not have the tilt angles.

PV Watts:

	PV Watts 154 angle	PV Watts 167 angle
Jan-16	706	731	4%
Feb-16	842	869	3%
Mar-16	1,094	1112	2%

So, the difference in azimuth already accounts for a chunk of my 6%...........................

[sensij]

How granular is PV Watts? I just entered my current address and the address of my former residence. Google maps driving directions says it's 6.8 miles between the 2 houses, so I'm guessing it's about 6 miles as a bird flies? I used the same parameters for both addresses and PV Watts shows the same electricity generation output.

The point to using PVWatts is not necessarily for location... as you see, the granularity is limited. If you use the SolarAnywhere option, I think the boxes may be something like 10 km x 10 km, about 6 mi x 6 mi, but I'd need to look closer to be sure. What PVWatts *will* clearly tell you is the effect of the different array orientations on expected output, with both azimuth and tilt contributing strongly enough to possibly explain the 6% difference (or more).

[ButchDeal]

Sites are shadow free other than snow accumulation.

ok so you have a 13degree difference in azimuth as self reported, (possibly more as there is a potential for ~5 degree difference there as well)
unknown pitch differences.

and you are concerned about a 6% difference in output?

The azimuth is most of that difference
Tilt is likely the rest.


not to mention the differences in solarworld vs canadian (canadian poly modules have highest diffuse light rating, so cloudy days they should slightly out perform) Solarworld black modules will slightly underperform on hot days due to added heat...
These differences would be tiny compared to the azimuth difference though.

[ButchDeal]

My inverter is the revenue grade model used for SREC reporting. No idea on the EnPhase setup.

Do not have the tilt angles.

PV Watts:

	PV Watts 154 angle	PV Watts 167 angle
Jan-16	706	731	4%
Feb-16	842	869	3%
Mar-16	1,094	1112	2%

So, the difference in azimuth already accounts for a chunk of my 6%...........................

you will need the tilt or at least a decent estimate of that. The bigger the tilt the more the azimuth will impact
as well as the tilt is likely not the same on the two structures causing its own variance

So the revenue grade meter in your solaredge has 0.5% accuracey

[J.P.M.]

My inverter is the revenue grade model used for SREC reporting. No idea on the EnPhase setup.

Do not have the tilt angles.

PV Watts:

	PV Watts 154 angle	PV Watts 167 angle
Jan-16	706	731	4%
Feb-16	842	869	3%
Mar-16	1,094	1112	2%

So, the difference in azimuth already accounts for a chunk of my 6%...........................

I suspect the unknown tilt may be a fair portion of the difference from the change in output diff. per month. Also, note that the PVWatts 3 month estimated totals show about a 2-3 % diff. Throw in Nov. & Dec. w/ their likely (?) 3-4 % diff. and the Nov- March diff. in az. output will go up some as well.

The PVWatts azimuth diff. looks like about half the total observed diff. Trying to find/explain the other 3 % is separating fly specks from pepper, particularly given the rest of the unknowns/uncertainties. You'll be lost in the noise.

[DanKegel]

To the OP: if you like informal competition, you may enjoy pvoutput.org. Check it out. It's pretty easy to set up automatic uploading from most monitoring systems.

[dust999]

Thx, I'll take a look at it.