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  • LG vs Panasonic vs Mission Solar vs Trina

    First off, let me preface by saying that I've done a lot of reading here, on other sites, and bought the dummies book. I'm also have an Electrical Engineering degree so I have a fair understanding of concepts. That said, I don't overestimate the value of practical experience and so I'm totally willing to take criticism and input, and if you read something that seems to indicate that I have a misconception, please feel free to call it out.

    After doing my research, I went on enegysage and got my three estimates and since I'm not sure whether I'm supposed to call out the actual installers here, I'll anonymize to a degree.

    State: Florida
    Purchase type: Cash

    Quote 1: $2.90 per watt before incentives
    Panel Manufacturer: LG
    Panel: LG330NIC-A5 NeON2 or Panasonic VBHN330SA16
    Number of panels: 35
    Watts per panel: 330
    System size: 11.6 kW (69% of billed usage)
    Inverter: SolarEdge
    Inverter Type: String with optimizers
    Inverter Warranty: 25 years (!)
    Notes: Note the extended 25 year inverter warranty. I'm keen on that, but I don't believe that LG is worth the extra money. This installer is willing to give me Panasonic panels for the same price as LG.

    Quote 2: $2.70 per watt before incentives
    Panel Manufacturer: Mission Solar
    Panel: MSE310SQ8T MSE PERC 60
    Number of panels: 37
    Watts per panel: 310
    System size: 11.5 kW (69% of billed usage)
    Inverter: Enphase
    Inverter Type: Microinverter
    Inverter Warranty: 25 years
    Note: I don't believe microinverters are worth the money but this installer seems to be pro-microinverter though they are willing to install string+optimizer

    Quote 3: $2.56 per watt before incentives
    Panel Manufacturer: Trina Solar
    Panel: TSM-340DD14A(II) TallMax Plus
    Number of panels: 34
    Watts per panel: 340
    System size: 11.6 kW (70% of billed usage)
    Inverter: SolarEdge
    Inverter Type: String with optimizers
    Inverter Warranty: 12 years
    Note: This panel seems to be 15% longer than than a "standard" solar panel. I'm wondering whether this will cause me any problems now or down the road.

    For context, here's a picture from a quote I got a couple of years ago that was for a ridiculous 70 panel system:
    Screen Shot 2019-06-13 at 2.52.27 PM.png

    Thanks in advance for your comments and advice.
    Last edited by lensman; 06-13-2019, 05:06 PM.

  • #2
    That older quote with 70 pv modules is likely about 17.5kW (assuming 250w PV modules )
    Now you are looking at 3 quotes of about 11.5kW
    Have you made the house more efficient?

    Also note that those TSM-340DD14A are 72 cell modules not 60 like your other two quotes.

    Did you leave out a quote? your subject mentions panasonic..

    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

    Comment


    • #3
      Originally posted by ButchDeal View Post
      That older quote with 70 pv modules is likely about 17.5kW (assuming 250w PV modules )
      Now you are looking at 3 quotes of about 11.5kW
      Have you made the house more efficient?

      Also note that those TSM-340DD14A are 72 cell modules not 60 like your other two quotes.

      Did you leave out a quote? your subject mentions panasonic..
      Hi @ButchDeal,

      Yeah, in the intervening year and a half we installed new windows, replaced our ducts, blew insulation into the attic and replaced the roof. This took down our electric bill by a quarter to a third. Also, that older quote was for 100% coverage and the newer ones are all around 70%, which I feel is a "safer" number since I anticipate getting a higher efficiency central AC compressor the next time we replace it.

      I added in the information on the Panasonic modules that Vendor 1 just sent me.

      Comment


      • #4
        Whatever you get, you have 3 separate roof planes (E, S, W) and will need at least 3 MPPT channels

        Maybe the trees have such an impact, you need microinverters. The pic, to me, (I'm assuming N is at the top) shows that only the E & W arrays are going to be useful and the 2 small S arrays are going to be in shade a lot.

        You need a good shade analyisis, it may not be a good site for solar, except for the un shaded areas. When those trees grow, you will have even more shade
        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

        Comment


        • #5
          If it were me, even though you plan to replace the HVAC with more efficient units, I would still target a larger array that covers more like 90-95% of anticipated usage -- it's hot and humid in FL. Do you have any EV's now? In 10yrs or less, I would expect at least 0.5 EV vehicles per household, perhaps more in more affluent households. EV's use a lot of electricity.

          I see you have a pool as well. Do you have a multispeed, 240VAC pool pump? These can save a lot of electricity as well.

          Is North up in your picture?

          Based on your electrical rates and current consumption, after the federal rebate on the array (30%), how many years will it take to break even based on your current quotes? Will you still be living there by then?

          I'd lean towards SolarEdge. Given that it looks like most of your panels are East/West. You could probably go up to ~15kW on the 11.4kW HD inverter. OR, split your array into two separate 7600W inverters (W+1/2 of S), (E+1/2 of S). But Enphase is fine, too.

          Does you PoCo have a limit for the size of residential Grid-Tied systemsl? Some PoCo's require extra insurance, fees, etc. above a certain size (e.g. 10, 12, or 15kW)

          $2.90 for Panasonic is a very good price. Not so much for LG Neon2. LG Neon R is more than Panasonic. Lots of other less expensive panels -- Trina, Jinko, Hanwha, etc. are good too, in the 2.60-2.80 range. I cannot comment on Mission Solar, but if it were me, I'd probably pass. Asian electronics are usually much better/more reliable than American.

          Are panel aesthetics important? Black frames? Silver frames? I would stick with white backsheets in such a hot climate. The Panasonics and LG Neon R have great thermal coefficients. Note that many of the new LG's (and any 72-cell panels) are physically larger than "normal." So sometimes, when they come to actually measure your roof, it doesn't quite fit like the salesman said it would.

          Comment


          • #6
            One other comment, you list your percentage of bill usage next to the PV DC kW at STC. Just making sure you know that you cannot compare these two numbers. Your annual PoCo usage is in MWh per year (Mega Watt Hours). You cannot compare this to the DC kW rating of the array. Based on your home's latitude, and the orientation and inclination of your roof faces, you must model the potential output of the array. This will give you the expected production (in kWh or MWh) based on the size in kW of your array.

            How many MWh do you use per year? And what is the cost per kWh?

            You can model the production (of each roof face separately) on PVWatts
            https://pvwatts.nrel.gov/

            Or using the Solar Edge designer tool (which you have to register for)

            As a very, very, very rough rule of thumb, depending on location, shading, angle, and other factors, the production of a PV system in MWh will be anywhere from 0.7x to 1.6x the DC kW rating of the array.

            For example, where I live in NJ, based on my roof orientation, inclination, and shading, my 12.2kW array only produces ~11-12 MWh per year. But a local colleague of mine with a more optimal setup (less shade, better inclination, etc.) gets a similar level of production from his 9kW array.

            Here's my system for example
            https://pvoutput.org/list.jsp?id=58372&sid=52103

            His lifetime, average, daily efficiency (kWh produced per DC kW of PV Array) is 3.614kWh/kW verses my 2.638kWh/kW. Needless to say his ROI is much better, too, given the smaller total investment for the smaller system, and choice of mid-tier panels.

            But I'm still happy with my system. I got the panels I wanted and needed to maximize production on my tiny roof. We both used the same installer, After covering ever square foot of it with 37 panels, I'm still only able to offset ~85% of my annual consumption. I do have an old HVAC. No EV or pool. New windows, roof, insulation, home energy audit with Energy Star, etc. Still electric rates in NJ are very low ~0.09kW plus ~0.04 for transmission. But we have SREC credits to help defray the cost of solar. So I should break even in about 5 or 6 years from now (system installed in June 2017).

            Comment


            • #7
              JSchnee21,

              Thanks so much for your analysis. Great questions!

              Yes, Florida Power & Light is my power company and I want to stay below their 11.5 kW limit for a Tier 1 system. They require a $1 million general liability policy and $400 fee for larger systems.

              My annual usage is down to 22,000 kWh after all the efficiency mods we've done, including a multi-speed pool pump. I'd guess I'm 5-7 years away from replacing the AC system. Beyond this I'll have to continue my fight with my wife and kids about the thermostat settings. We're also getting a Sense electricity monitor installed so there's hope for finding other savings.

              The modeling in the proposals is fairly accurate to what I did myself in pvwatts. I came up with 16,483 kWh/yr and the installers production estimate is 16,490 kWh/yr for the 11.5 kW system. It's actually remarkably similar. That's about 75% of my past year's usage. I think my usage is a little down from what I entered in energysage late last year, accounting for the 5% coverage difference.

              I did some shade modeling using shadowcalculator.eu and it looks to me like there could be some tree shade issues before 10 am and after 3:00 pm from November through January.

              I got a proposed layout from the installer #2. They said they could sub in Panasonic 330 watt HITs for another $3k, taking me to $2.95 per watt for that bid, which includes Enphase micro-inverters. At $0.12 per kWh electricity, my payback period will be about 11 years.
              Screen Shot 2019-06-17 at 1.35.22 PM.png
              Last edited by lensman; 06-17-2019, 02:16 PM.

              Comment


              • #8
                I am wondering if you are using a huge amount of KWH running an obsolete air cond
                system, esp one using R22? If so you could cut that usage in half by going to mini
                split R410A technology, and get several other advantages too. It is even possible to
                get units powered directly from solar panels, so this would not add to your 11.5KW
                limit. These have a dual capability of partial or all line power usage if lacking sun.

                They can heat too, at a lower cost than propane. Bruce Roe

                Comment


                • #9
                  Originally posted by bcroe View Post
                  I am wondering if you are using a huge amount of KWH running an obsolete air cond
                  system, esp one using R22? If so you could cut that usage in half by going to mini
                  split R410A technology, and get several other advantages too. It is even possible to
                  get units powered directly from solar panels, so this would not add to your 11.5KW
                  limit. These have a dual capability of partial or all line power usage if lacking sun.

                  They can heat too, at a lower cost than propane. Bruce Roe
                  Our air conditioner was replaced in 2014, so it's not using R22. Are you suggesting that my electric bill is high for a 1968-built home in South Florida with a swimming pool? I've frequently commented to my wife about this wrt the thermostat setting, but there's only so much I can do short of getting a divorce.

                  The average FPL customer uses 14,000 kWh a year, the median customer uses 11,000. My pool pump only accounts for an extra 1000-2000 kWh a year. God only knows how much of the electric bill is due to the wife or kids turning down the thermostat to 70 degrees! I will say that the bill is a lot better after spending $20k on new windows and $4000 on new ducts and attic insulation.

                  I'd really be interested in hearing about the bills for other single-family residences in South Florida. Do crazy thermostat settings and excessive electricity use count as "pain and suffering" in divorce decrees?

                  Comment


                  • #10
                    I also replaced my AC unit in 2014. The replacement had a SEER of 13, honestly it was a disappointment
                    in several ways. In 2018 I installed heat pumps with a SEER of 33. These were able to reduce my HVAC
                    energy by more than half, along with several other benefits. What are your numbers?

                    Get numbers, how many of your KWH are going to air cond., what are the numbers
                    for the other stuff? Find out the SEER or EER or COP of your current equipment.

                    The suggestions above of feeding perhaps 15KW of E and W panels into an 11KW inverter works
                    when set up right. Been doing it here for years. Bruce Roe

                    Comment


                    • #11
                      My FPL bill peaks in summer at about $150/month. The house is only 1850 sq.ft. and no pool. New roof (white shingles), maxed out the insulation in the attic, house is also white with only a bit of color trim. Impact windows (make a huge difference in heat transmission), two year old A/C unit, LED light bulbs, etc. Programmable thermostat so we are not cooling a lot when nobody is home. No solar panels other than backup power to charge a small LiFePo4 battery to power my CPAP and charge cell phones in case of long term power disruption (i.e. hurricanes). Winter power bills less than $100. Efficiency is the way to go. I understand the WAF is a big factor. Perhaps if you let her know how much you could be saving in pairs of shoes it would sink in. (no offense intended).

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