Enphase M190/M190IG/M215IG/M250 Head-to-head-to-head

[QueenBee]

Of course, this station will be completely outgunned by QueenBee's for peak power, peak daily energy production and monthly energy production. But maybe, just maybe, the difference in latitude and climate between here and there will allow me to take the award for annual energy production!

That'd be a quite the feat! Your unobstructed view of the sun certainly has mine shading beat but my higher output panels and sheer number make up for that

[RegGuheert]

That'd be a quite the feat! Your unobstructed view of the sun certainly has mine shading beat but my higher output panels and sheer number make up for that

Not so fast! It's the area FACING THE SUN that counts. Clearly you win this time of the year. But in wintertime, my system should win that contest.

I suspect the following months your system will outproduce mine:

May
June
July
August

These months I expect my system will outproduce yours:

October
November
December
January
February
March

The following months they should be about equal:

April
September

The question is how they will come out overall. That may depend upon the weather!

[RegGuheert]

Here is a trivial observation of a difference between the M190s and the M215s: The M190s ALL wake up in the morning (DC Power Too Low: Clear) before ANY of the M215s wake up.

[RegGuheert]

I finally got a moment where it was cool enough and/or bright enough to be able differentiate between the M190s and the M215s simply by the output power of each:



That's about all the M190s can do (199W), but I'm pretty sure from images I've seen from others' arrays that the M215s still have another 10W in them (225W).

A quick look at voltages reported by the inverters tells me that there is very little difference between a string of 7 M190s (on the top row of the garage) or the string of 12 M215s (all M215s) in terms of voltage drop. (Of course the measurement resolution is only 1V and I do not know how accurate these things are, but it's all I have to go on.) Each string indicates a voltage of 255VAC at the end of the string and 254VAC at the inverter closest to the panel. This is so even though the wiring for the M215 string is carrying 86% more current than the wiring for the M190s. The difference is that the M190 wiring is likely longer from between the two ends of the strings and is 14AWG versus 12AWG with the M215s. Also, each string is fed by a 12AWG wiring from the breaker panel, but the M190 string is about twice the round-trip distance from the panel as the M215 string. That explains why both strings are at about the same voltage at the first inverter in spite of the lower current in the M190 string.

[RegGuheert]

Just for grins, I have run some calculations in the latest version of PVWatts for my old system, my new system with the additional 12 inverters and for QueenBee's current system of 73 panels. For consistency's sake, I made the DC to AC Derate Factor 0.9 for all runs.

Here are all our numbers for PVWatts with original 42 PV panels, 2011, 2012, 2013, 2014, PVWatts with 54 PV panels, and QueenBee's PVWatts predition:

Code: Select all

Month    PVW42   2011   2012   2013   2014  PVW54  PVWQB  Units
---------------------------------------------------------------
January    916    669    869    822    857   1229    407   kWh
February   702    158   1085    866   1054    915    990   kWh
March      965      0   1350   1152   1113   1240   1311   kWh
April     1465      0   1465   1495   1338   1899   2006   kWh
May       1583      0   1477   1491   1457   2074   2305   kWh 
June      1268      0   1478   1368   1521   1666   2152   kWh
July      1448    595   1395   1406   1880   1902   2685   kWh
August    1442   1347   1447   1333   1794   1875   2242   kWh
September 1209    910   1295   1414   1577   1555   1988   kWh
October   1304    931    981   1034   1258   1713    931   kWh
November   864    949   1041   1018   1227   1154    373   kWh
December   820    803    612    669    812   1108    287   kWh
---------------------------------------------------------------
Totals   13986   6362  14495  14068  15888  18330  17747   kWh

While I was able to get the PVWatts numbers to come out about right for the year by using the DC to AC Derate Factor of 0.9, I will note that they do not seem to match up for all months. Specifically, the predictions seem very high for October and a bit low for February and June.

Interestingly, PVWatts has my system outperforming QueenBee's in only four months: October through November, but the differences shown in those four months are enough to make up for the small number of higher months. In the end it seems clear that the weather will be the factor which determines which system produces more in a given year. Since I have been watching the two systems, QueenBee has had lots of clear days while I have seen almost none.

It is interesting to see the differences in how these systems perform!

[RegGuheert]

More than a year has passed since I added the M215IGs to the system and I will say that the production numbers for the M190s and M215IGs are nearly identical, with all hovering right around 335 kWh.

I changed the title of the thread to reflect the new status of my system. In addition to the M190s and the M215IGs, I added an M190IG on September 18, 2014 which I received as a replacement for a failed M190 and I have just purchased four M250s to replace four M190s which I recently sold.

To make a better comparison for the future, I have decided I will line up an assortment of inverters under the top row of panels on the garage. Here is what I expect to end up with:

M190 - M250 - M215IG - M250 - M190IG - M250 - M250

(The last panel on the right gets shaded in the morning, so it will not help with the comparison.)

I may need to cut off one of the connectors on the Engage cable to make it work. If that happens one of the M250s will go somewhere else and there will be two M190s on the far left end.

I do not expect to see any difference between these various inverters sitting while sitting under 235Wp PV modules other than the M190s being less reliable.

[RegGuheert]

Here is what I expect to end up with:

M190 - M250 - M215IG - M250 - M190IG - M250 - M250.

I ended up with something quite similar (on the top row of the garage array):

M190 - M215IG - M250 - M190IG - M215IG - M250 - M250

FWIW, the M190 was built in 2010, the M190IG and M215IGs were built in 2014 and the M250 was built in 2015.

The two on the left are in a different string (M190-style cabling) than the five on the right (Engage cabling). Again, the M250 on the far right is shaded in the morning, so it will not be useful for comparison. The M250 just next to it may also be useless for the same reason. Also, it is possible that the M190 on the far left over-reports how much AC it produces, so its numbers should be taken with a grain of salt. (I have seen this over-reporting happen prior to failure with some of my M190s.) The other four inverters should be valid for comparisons.

Here is an action photograph I took of three of the four types of competitors:



(BTW, the one in the middle that is simply labeled "enphase ENERGY" is an M215IG.)

I'll report back after I have some comparative data. There is no reason to believe that the M250s will produce more electricity than the M215IGs, but I also expect that neither of them will outproduce the M190 or M190IG by any significant margin, if at all. Time will tell.

[RegGuheert]

Here is a picture of the production over the period July 16, 2015, until August 2, 2015. (Only a portion of the total array is shown to improve readability.) I have annotated the inverter type found beneath each PV module for reference:



Note that the two columns on the farthest-right edge of the garage are shaded in the early morning and the module on the bottom right on the house gets some afternoon shade. As a result, those should produce a bit less electricity than all the rest, which are in full sun. Also, the inverters third and fourth from the right in the middle row of the Garage Array are malfunctioning daily with "Grid Gone" events and therefore produce slightly less electricity.

It's a bit interesting that the old M190 in the top-left corner produced about 3% more electricity than its neighbors in that row. I attribute most of that difference to the cooling effect of the westerly winds which hit it first, but it may also be simply that the old M190 inverters tend to report more production leading up to their failure. Likely both effects are involved.

Overall, as expected, there is no real difference in production between the M190, M190IG, M215IG or M250 during the heat of the summer. It will be interesting to see if any real differences are visible during the coldest periods of the year.

FWIW, at this point, the roof arrays now contain the following:

25 - M190s (Manufactured in late 2010)
12 - M215IGs (Manufactured in early 2014)
4 - M250s (Manufactured in early 2015)
1 - M190IG (Manufactured in mid 2014)

The field array contains the following:

12 - M190s (Manufactured in late 2010)

Since the field array contains 72-cell PV modules (in a climate which gets cold enough to break the new-style inverters), I will need to keep the original-style inverters out there as long as possible. If I eventually get to the point at which I have 42 new-style inverters on the roof and I experience another failure, I may be looking to swap new-style inverters for the old M190s from someone such as Weatherman that has only 60-cell modules and/or lives in a warm climate. When and if that will eventually happen I have no idea.

[RegGuheert]

Since the results are interesting, I thought I would post production of the inverter shootout from July 9 through today:



Interestingly the M190IG, M215IG and M250 are reporting that they produced exactly the same amount of energy over the previous 3.5 month period and if you look at the two M190s on the left end of the second row, they also reportedly produced that exact amount of energy.

As for the M190 in the upper left, I suspect its high production is the signature of a future failure. (The second inverter which failed in this array was reporting the highest production in the array just prior to its failure, but the replacement reports normal production.)

It will be interesting to see what winter brings.

[pclifton]

Hi RegGuheert,

Perhaps you can educate me about this:

Since the field array contains 72-cell PV modules (in a climate which gets cold enough to break the new-style inverters), I will need to keep the original-style inverters out there as long as possible.

I have 31 Sharp 235W mono panels as well as some 375 SW. Twenty-four of the Sharps are connected to the M190s. As you know, two of my four replacements have been the M190IG(s). I have been considering replacing all of the M190s with the new S230(s) when they are out at some point. I installed my systems and as the years go by I will reach a point where I can't keep swapping out inverters. I ran into that last year while I was blind.

Anyway, your statement gives me some concerns about that plan -- if I understand you correctly...

Thanks,
Ken Clifton