Finally chose a system and starting the process!

HX_Guy
HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
After all the research and everything, I finally narrowed everything down to one setup and installer and we're starting the process! The installer is currently working on the design and will be submitting for permits next week. They are a newer company without a whole lot of experience but I've talked to a few of their customers and they are happy with their systems and the company. I'll be supervising along the way though and asking lots of questions on here to make sure everything is looking good, hope you guys don't mind. :D

We're going with 50 CentroSolar BP6-250 panels with a Fronius 11.4 inverter setup in 5 strings, 10 panels per for a total system size of 12.5kW.
There will be 30 panels facing south and 20 panels facing east, in this configuration.

5stringssmall.jpg

Comments

  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Finally chose a system and starting the process!

    You really should separate the south and east panels onto different grid tie inverters for maximum output.
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!

    Even if they are on different strings? I thought that would be ok. How about shading? If the shade only hits one string, will it affect the others?
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Finally chose a system and starting the process!
    HX_Guy wrote: »
    Even if they are on different strings? I thought that would be ok. How about shading? If the shade only hits one string, will it affect the others?

    I am no expert on the fronius line, perhaps it has 2 MPPT trackers.

    Shading is bad for the whole string.
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!
    solar_dave wrote: »
    I am no expert on the fronius line, perhaps it has 2 MPPT trackers.

    Shading is bad for the whole string.

    The Fronius only has 1 MPPT.

    As for shading, I know that it's bad for the whole string, but is it bad for the whole system? If string #1 is shades fully, does it affect strings #2, #3, #4 and #5 any or at all?
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Finally chose a system and starting the process!
    HX_Guy wrote: »
    The Fronius only has 1 MPPT.

    As for shading, I know that it's bad for the whole string, but is it bad for the whole system? If string #1 is shades fully, does it affect strings #2, #3, #4 and #5 any or at all?

    I will defer to the Coot, BB or others on the shading.
    I certainly would look at dual inverters, the cost should not be much different except you probably need to have a AC combiner between the main panel and the pair of inverters. That might raise the cost slightly.

    Like this:
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Finally chose a system and starting the process!

    This looks like a job for micro-inverters.
  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    Re: Finally chose a system and starting the process!

    I would run from an installer that is making the rooky mistake of installing a single-MPPT inverter like a Fronius on a dual orientation array. I know there is not much choice in the above 10kW territory, but best solution is to use 2 smaller inverters, one for each roof orientation.
  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: Finally chose a system and starting the process!

    As Carlboocoot suggested Micro Inverters should be considered. You could select to split it between two GT inverter also. I would try and get as many of your strings? Onto the south facing roof. Can't see exactly what you have for obstructions on the open areas but it would definitely simplify the installation of your system either way you choose. See lots of extra wiring, conduit runs etc with either inverter system.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!

    From what I've read, there is concern with micro-invereters and the super hot AZ summers or are the newer micro-inverters better now? Also a lot more added cost, about $5,000 more is what I'm estimating looking at 48 micro-inverters vs 1 central inverter online.

    As for the panels, there is a 2 story house south of ours which is why you see the empty area in the middle of the south roof. If that wasn't there, this install would be super easy.
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!
    solarix wrote: »
    I would run from an installer that is making the rooky mistake of installing a single-MPPT inverter like a Fronius on a dual orientation array. I know there is not much choice in the above 10kW territory, but best solution is to use 2 smaller inverters, one for each roof orientation.

    Solarix, from what I've read, with the new inverters they are much much better at handling dual orientations with a single MPPT and claim about a 1% difference between single MPPT and dual MPPT. The bigger problem is shading and according to Fronius, that's when you should consider multiple MPPTs or dual inverters: http://www.fronius.com/cps/rde/xbcr/SID-33F6EA33-BD64BEF0/fronius_international/SE_TANA_Inverter_selection_for_complex_PV_systems_EN_288815_snapshot.pdf
  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    Re: Finally chose a system and starting the process!

    I don't know where you read that single MPPTs are getting better at dual orientations - maybe from the single input inverter makers that are getting blown out by PowerOne and SMA which do have it. Look, arrays that are 90deg different in orientation are operating very differently on their I-V curve and a single MPPT operating point is going to be an unnecessary compromise.
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Finally chose a system and starting the process!
    solarix wrote: »
    I don't know where you read that single MPPTs are getting better at dual orientations - maybe from the single input inverter makers that are getting blown out by PowerOne and SMA which do have it. Look, arrays that are 90deg different in orientation are operating very differently on their I-V curve and a single MPPT operating point is going to be an unnecessary compromise.
    Here we go again!

    As long as there is no partial shading involved anywhere in the two strings being combined, the operating point of the two strings will indeed be at totally different points on the I-V curve if they have different orientations. BUT those two operating points will be at the same voltage. That is what allows one MPPT controller to reach the true MPP for both strings simultaneously.
    This is not just a theoretical analysis. Actual experiments (by both SMA and Xantrex if I recall correctly) demonstrate that this is true.

    The very small difference in Vmp between the two strings, based both on insolation and on temperature, is not enough to justify the expense of a second inverter, or even a second MPPT input on one inverter unless that is a "free" feature of that GTI model.
    SMA SB 3000, old BP panels.
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!

    Intedog: What if there are 4 strings (3 facing south and 1 facing east) and any of the south facing strings do have shade? How will that affect the other 3 strings?

    According to this site, other strings which have no shade on them will not be affected by a shaded string, is this correct?

    http://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/

    "If, for example, shade from a tree or a chimney is cast on even one of the panels in the string, the output of the entire string will be reduced to virtually zero for as long as the shadow sits there. If there is a separate, unshaded string, however, this string will continue to produce power as per usual."
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!

    This is the new configuration I came up with and the installer agrees it's the best use of roof space given what we have to work with so this is what we're going forward with.
    They will be drawing up the plans on their end in the next day or two and submitting to the electric company and the city.

    FinalSetup1.jpg

    FinalSetup2.jpg

    I did ask about multiple inverters and they said it would be around $4000 more to do dual inverters between the cost of the extra inverter, the combiner panel and the extra labor. Seemed high so sticking with a single inverter and making the best of it.
  • DaveH9
    DaveH9 Registered Users Posts: 13
    Re: Finally chose a system and starting the process!

    i would change the design. 5 arrays with just 2 mods each would mean conduit run between them. Total of 9 arrays, man that's a nightmare installation, even with micros.Simplify, it looks like a young companies design that has not learned the hard way yet. Is the south main roof shaded? If not that should be completely filled before considering any other roofs. The presentation is nice, just needs to be cleaned up or switch to another installer. (posted before your design change it is better now)
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!

    Heh, yeah that original design didn't work. I need 12 panels per string so had to redesign. And I did the design myself, so definitely a "young company". ;)
    Our roof is almost impossible to work with, so many shapes and angles and then have to take into consideration all the setback requirements.

    What's your thought on the final design? Seems ok?
  • KozmoK
    KozmoK Solar Expert Posts: 42
    Re: Finally chose a system and starting the process!

    I am still a Rookie but...

    The only thing that makes sense to me is dual/multiple Inverters (Based on your roof and its pitches and angles). Since it will drive the cost up, you already ruled out using micro-inverters because of the heat here in the desert would probably destroy a few over time.

    As I have PM'd you before: 1 SolarEdge Inverter,1 Optimizer per panel. Use any panel you want, mix and match, put it in ANY orientation. View almost live input data from your panels just like Enphase. SolarEdge Optimizers are Individual DC MPPT's and do no inverting, so it uses less components to break down.

    I have this setup on my roof - although not really needed for different orientations, I like to view panel output individually.

    SolarEdge was about the same price as the Enphase setup, as Enphase makes you buy a gateway, The SolarEdge Inverter has the gateway built in saving $400-500.

    My APS Bill last month was $71.00 , On a 8.1kw SolarEdge System - 2 Old AC Units running all the time (Seer 10) and a pool pump on for 7 hours in the night, and a woman who likes to do 2 loads of laundry per day. I produce ~ 53 kwh a day.
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!

    Kozmo: Since I last updated, I've actually been talking to my installer about different options...first a dual inverter setup each with dual MPPTs, so each string would be on it's own MPPT, but the quote he gave me was too high in my opinion (additional $3800 compared to the single inverter setup) so now I asked for a quote on SolarEdge.

    I'm hoping it will be less than +$3800 of the dual inverter setup. In my original quote, the Fronius 11.4 inverter was priced at $3,500. Looking online, the SolarEdge ES10000US inverter is $2200 (shipped) and each optimizer is $63.80 (shipped), I need 48, so $3057 for a total of $5257. If I subtract out the cost of the original $3500 inverter, it should be about +$1757 to do the SolarEdge setup...say $2000. It'll probably be a little bit more because the installer has never used SolarEdge and even though it looks like it basically the same install as a regular string inverter, aside from attaching each optimizer to the rail with one screw, they will probably still charge a bit because it's new to them and they have to spend time researching it. I'm hoping that close to what the quote will come back at so I can finally get this project moving.
  • KozmoK
    KozmoK Solar Expert Posts: 42
    Re: Finally chose a system and starting the process!

    What's nice is when the panels are live with optimizers, they only output 1 volt each until the Inverter tells them its okay to start. This makes it safe for the installer.
    If he needs some help programming it, I actually did mine with tech support on the line, its pretty easy. Basically you accept the defaults upon a factory reset, you then tell the inverter
    to go into Pairing mode - and it will go out and start counting all the optimizers you have. If its correct, then turn the optimzers on.

    They will need to record all the optimizers serial #'rs and the inverter serial #, and setup an account on solaredge site.

    Your guys can come over and check my system out if you want! I am only 2-3 blocks away :)
  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    Re: Finally chose a system and starting the process!

    Update: Got a quote from the installer on the SolarEdge setup and it's an additional $1700 compared to the single Fronius inverter setup so I'm going that route. Also switched from the 250w CentroSolar panels to 310w Canadian Solar panels, sent them my final layout and they said they will get to designing asap and submit the plans to the city and electric company by end of the week.

    1 string of 11 (green)
    1 string of 12 (yellow)
    1 string of 16 (blue)

    I would have put that lone yellow one with the rest of the blue but the max watts per string with SolarEdge is 5250w which means a maximum of 16 panels per string.

    Aerial_View.jpg