Enphase comparison question?

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cygone
cygone Registered Users Posts: 6 ✭
in Solar Beginners Corner #1
I recently installed an array of 17 Enphase M215 inverters matched with 17 Sharp L240 Watt panels. I made my system public https://enlighten.enphaseenergy.com/public/systems/mFMe48733 and while viewing the map I noted a very similar system about 30 miles north in a very similar climate zone, https://enlighten.enphaseenergy.com/public/systems/WtKP46571 . We have had seven days of bright sunshine in both locations and the system to the north significantly outperforms my system. Out of curiosity I called the installer of the northern system and asked what type of solar panels and inverters they were using. I was told they had installed Enphase M215 inverters and REC 220 Watt panels.

My azimuth is 201 degrees and the northern system is 184 degrees. According to the California efficiency calculator this should not matter much. My tilt angle is about 30 degrees and I do not know the tilt angle of the northern system and wonder if it could matter that much. I realize I have some shading issues in the early morning and evening but at mid-day I would expect to outperform the northern system. If someone can explain why the northern system outperforms my system please help. Please understand I am not unhappy with my systems performance (In fact it is better than expected) I just wonder how they get more for less up north. If someone has any ideas.........
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #2
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    Re: Enphase comparison question?

    Very interesting. I see what you mean. Your system appears to be shaded at the ends of the day and reduced at the peak as well. Are your modules mounted on tilt racks such that they can shade each other when the sun is low? This would explain the ends of the day being knocked down. The reduced peak could be caused by heat affecting the PV efficiency. What type of roofing do you have? and is the array well ventilated?
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  • cygone
    cygone Registered Users Posts: 6 ✭
    #3
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    Re: Enphase comparison question?

    My shading issues are caused by two large pine trees on the far left and far right but there are no trees or shading problems in the afternoon and I do not get close to the same output as my northern neighbor. I have a composite shingle roof and the average temperature for the period i followed was always lower in my town than my northern neighbor. The array is well ventilated about six inches from roof mounted at 30 degrees. It is possible my neighbor I guess has a better tilt angle but could that make this much difference.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #4
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    Re: Enphase comparison question?

    30 miles is a nice Sunday drive... to go have a look yourself.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
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    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #5
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    Re: Enphase comparison question?

    My best advice would be to not look at the performance of a non-identical system. I was driven nuts by watching my system's performance compared to an almost-in-laws (daughter's in-laws) system. They are the same Enphase 190's, the same 230watt brand of panels, the same installer, but they outperform mine by about 1%. The only difference I could find was my utility feed cable was undersized from what it should have been (3% voltage drop is ok, so that's what the electrician installed), that's the only difference besides mine being fed from a different utility feed (different address, 4miles apart). Now I don't worry about it because I don't look at the other site's public offering....problem solved.

    Maybe the other in your case is ground mounted, oriented and/or angled to a different degree, whatever. As you can see in my case even exactly the same (well, almost) and you can get variations in output.

    Ralph
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #6
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    Re: Enphase comparison question?

    I agree with Ralph, trying to compare two different systems with the different variables that there could be, will drive you nuts. Our two systems are very similar and I am in the Midwest. I took a day that had a smooth output curve, at the peak of the day yours was outputting 164.6 per panel and mine was 164.4. My panels are REC-235's. While the other system you posted output was 185.8 per panel, overtime the 20 watt per panel difference would be big in the total harvest.

    If you take a loose panel outside and move it around, it doesn't take much to change the output 20 watts. Not much you can do but about it. At one time I thought about raising the upper end of the panels with taller standoff's, but I just said what the heck, I'll live with it.
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  • Munichtexan
    Munichtexan Registered Users Posts: 1
    #7
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    Re: Enphase comparison question?

    It sounds like the trees may be the difference in performance due to shading. I am just now looking at using Enphase and have been searching the internet to try and figure out what data is actually available to compare panel to panel performance? Is it possible to take data from two different panels and compare the Vmax, Imax (DC and AC) to compare panel versus microinverter performance? I would also like to be able to look at Vdc and Idc available which is lost prior to the microinverter delivering AC power. Not sure if I can post an email address here, but I did ok for emails to be sent directly to me.

    In looking at the shading on my roof, at different times of day, various shadows will occur. My roof is anything but ideal for solar installations. It does not even point north/south. I am looking at maximum roof coverage primarily to provide a power output throughout the entire day. My roughly east facing roof would provide early morning, roughly west facing would provide late afternoon and I have some roof ridges that actually point roughly south.

    I have been looking at Tigo Electronics and SolarEdge optimization DC circuits, but have decided to build my system slower so I can study the best layout approach including a full shadow analysis in regards to placement of the panels.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #8
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    Re: Enphase comparison question?
    cygone wrote: »
    at mid-day I would expect to outperform the northern system.
    Why is that? It simply being 30 miles more north is going to make far less difference even than the small difference in azimuth. Have you run PVWatts v2 on the two locations to see if there is a statistical difference in meteorology between the two locations? Maybe it's cloudier where you are.
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  • jzchen
    jzchen Registered Users Posts: 23 ✭✭
    #9
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    Re: Enphase comparison question?

    I just took a look at both pages. I kept having to close and reload because I couldn't tell which one was yours or the others. I looked at the peak for today, and yours is higher at 2.3kW while the other is 2.26kW. This is as would be expected since you are further south, possibly negligible as someone stated, and have a "better" system. I think the shading is really hurting your output. If you look at the panels the ones on the right of yours are producing much less than the ones on the left. The other system looks unshaded, just glancing at the consistency of output from each panel...
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