7-10kW Grid Tied System in New Jersey

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  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    The last article I read about Evergreen's business was about how they keep lowering costs and will continue to do so as they shift most of their production to........China.

    I didn't mention it in this thread, but I'm not an Enphase booster. I'm not installing them myself because in general, inverters are pretty reliable, but still, they are the least reliable part of the system. I don't really want 30 inverters hidden under the array on every job I do and have to tear up an array whenever there's a problem with an inverter.

    If I had a job where someone just had 5 modules or something, that'd be a good project for enphase. That said, I haven't installed any yet, so I'm not speaking from experience, but I mostly subcontract to other installers so some day soon I'm sure one of them will sell an enphase job that I'll install.
  • mike95490mike95490 Solar Expert Posts: 9,358 ✭✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    There may never be a reason to R&R an Enphase, either the owner let the monitoring lapse and has no idea it's gone bad, and the electric bills just got bigger and bigger, or (tin foil hat time) the data you get from the decrypted master server shows all inverters working, but they are really dirty and you should call someone to wash them. See, the owner let the panels get dirty, the inverters are working fine....
    Powerfab top of pole PV mount | 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 ,

  • solarteksolartek Solar Expert Posts: 69 ✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey
    And why Enphase can sell the inverters below cost, just like the Cell Phone company's

    Got to give Enphase credit, the PR is convincing allot of posters to use the inverter when it has zero advantage to harvest. All the BS about partly shadowed arrays is a fix for a problem that shouldn't have PV panels installed in such locations in the first place. I guess PV has gotten big enough that its about shoveling product, not installing productive systems

    On the comments on whether a company is having financial difficulty, who cares, either the panel works or it doesn't. If PV production follows other industry's, in 5-10 years all PV will be made in China, so comparing a company in Japan vs Germany is a useless point, they all can't compete to China.

    Evergreen isn't going anywhere, The stock or bond holder may not be happy, but the company will have no issue with wiping out the stock or bonds holders and happily keep going


    "Zero advantage to harvest." While I can agree that for ideal locations (no shading, ideal array orientation and tilt) and very tight power tolerances on the modules there will be little to no advantage to using micro-inverters over a standard string inverter design. But not all modules and array locations are the same and so a case can be made when micro-inverter based designs have an advantage.

    Let me ask the following question. In an array of, say, Sharp modules with a -5% / +10% power tolerance mounted in an ideal location without shading do you believe that the amount of kWH harvested will be the same between a string inverter design and a micro-inverter design? Or do you believe that the difference is not economically worthwhile?

    And with regards to who cares about a solar manufacturer's financial stability and it's ability to honor a long term warranty...I care. Since I'm putting my reputation and financial stability on the line when giving 5 - 10 year system warranties on an installation. A panel working today is immaterial to the concern about a panel having an issue 8 years down the line and there being no recourse because the manufacturer is no longer in business. Yes they make a quality product. Yes the likelihood of having an issue with the panel long term is very low. But that's also true of other manufacturers; ones in better financial shape. Evergreen may or may not survive, I don't know and neither do you. Is it really such a "rare" event for companies, even big companies, to go out of business?

    Scott.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    Technically, the maximum power point on a PV panel is quite flat. What this means is you can have a string of panels with different tolerances and they all self adjust to the lower current, sound horrible as Enphase promotes but what is ( intentionally ) over looked is the panels that are operating at a slightly lower current are operating at a higher voltage so the still are harvesting very close to the name plate wattage.

    As long as you have a single string, a 5% difference between the panels current will be offset almost entirely by the individual panels operating at above the vmp voltage and hence there is little if any loss and total harvest. A central inveter is superior in efficiency to the Enphase, 95-97% for the newest transformer-less units.

    The raw cost in hardware of per module inverters is close to 2X the cost a central inverter, the monitoring is free ( central ) and your not subjecting the inverters to temperature cycling that is an impossibility that those inverters will last anywhere near the claims Enphase and others make. I'm a hardware engineer with close to 30 years of bring products to market, it defies everything I know and I call it as I see it, Its all savvy and slick marketing program to sell a product.

    There is nothing except interconnections that can fail on a solar panel, and if need be can be field repaired. On a percentage basis, its probably in the sub hundredths of one percent having a panel failure, much more likely electronics are BOS stuff

    As warranties, just based on what is likely to fail, you will be changing an inverter when you have 30-40 of them on a roof every few months for free long before you will ever see a solar panel fail. I makes absolutely no sense to be worried about panels and giving the new on the block inverter company a pass. Lets have this talk again in a few years ...

    It becoming very obvious, installers are not technical enough to know the difference between these products or even if they solve a real problem and be able to challenge the manufactures on their claims, neither are the customers and the company that has the best things printed get the sales. Enphase is making claims for there inverters that defy the electronics parts contained in them are capable from a durability point, doesn't matter, they can sell a few million, have an IPO and later when things start failing they will just start a new LLC with the insiders laughing all the way to the bank. 20 year prepaid for data monitoring, what a scam:roll:
  • brynnerbrynner Registered Users Posts: 5
    Re: 7-10kW Grid Tied System in New Jersey

    In my case, Enphase seems to be logical due to the orientation on the roof with panels on the dormer oriented more southerly than the southeasternly oriented other modules.

    An installer today stated that he uses ET or Suntech panels. Never heard of ET, but he said the wattage on them is 175. I am trying to identify the reason to go with a lower wattage panel vs. the Sharp 230. I understand they are probably smaller, and I would just need to buy more, but I'm basically trying to find the most wattage per sq. foot, which I assume would come with the larger Sharp panels.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    use a second central inverter for the different orientation, A Xantrex GT2.5 is like 1700.00 , or about 6 of the Enphase with the extras gizmos added in

    The Enphase are 190 watt maximum ( or whats listed on the sponers site ), not a good match for a 230 watt panel
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    It's pretty easy to find the specs online (I would but I'm on my phone) the higher power modules are generally just bigger and pretty much the same watt per sf. Sunpower and sanyo are the only modules that are significantly better watt per sf, but they are significantly more $ per watt. Of course different modules have different shapes and some fill some spaces better than others.
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey
    The Enphase are 190 watt maximum ( or whats listed on the sponers site ), not a good match for a 230 watt panel
    You're comparing AC to DC power outputs, there. Enphase actually recommends 230w DC STC panels since in real life, panels very rarely get close to their STC rating except on very cold, sunny days with the sun shining directly on the panel.

    Once you factor in power loss to inverter inefficiency, siting inefficiencies, dirty panels, temperature deratings, aging panels, etc, you find that in most cases 230w panels maximize your output while minimizing the cost of inverters.

    And if you think your panels will consistently push out more than 200w DC, then drop the panels down in size a bit if you're worried about losing that fraction of a percent of total power output.
  • solarteksolartek Solar Expert Posts: 69 ✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey
    Technically, the maximum power point on a PV panel is quite flat. What this means is you can have a string of panels with different tolerances and they all self adjust to the lower current, sound horrible as Enphase promotes but what is ( intentionally ) over looked is the panels that are operating at a slightly lower current are operating at a higher voltage so the still are harvesting very close to the name plate wattage.

    Flat, huh. Take a look at this datasheet for the Suntech 175W Mono panel. The peaks in power output versus insolation don't look "quite flat" to me. By your explanation above a module testing at 5% less of nameplate power will not actually be at 5% less power output from the magic of connecting it in series with other modules?
    As long as you have a single string, a 5% difference between the panels current will be offset almost entirely by the individual panels operating at above the vmp voltage and hence there is little if any loss and total harvest. A central inveter is superior in efficiency to the Enphase, 95-97% for the newest transformer-less units.

    But, except for Evergreen based designs, most systems above 2-3kW are never single string designs. And I wouldn't call central string inverter efficiencies so "superior".

    Enphase M190 95.0% (CEC)
    Enphase M210 95.5% (CEC)
    SMA SunnyBoy 3000HFUS 95% (CEC)

    The raw cost in hardware of per module inverters is close to 2X the cost a central inverter, the monitoring is free ( central ) and your not subjecting the inverters to temperature cycling that is an impossibility that those inverters will last anywhere near the claims Enphase and others make. I'm a hardware engineer with close to 30 years of bring products to market, it defies everything I know and I call it as I see it, Its all savvy and slick marketing program to sell a product.

    Not 2X. More like 1.2x - 1.6x depending on the size of the central string inverter.

    And I don't normally mention my background in these discussions, but I do have some familiarity with electronics and accelerated aging and testing. (Ph.D in Electrical Engineering, 15 years in the R&D group of a semiconductor company doing RF communication devices and systems for military, space, and telecommunication systems before changing fields). I've actually looked long and hard at the Enphase product and had a few discussions with some of their engineers about the product before I decided to move forward with using it. No doubt I'm biased because the technical background of the people I spoke with was telecom and I'm familiar with the type of rigorous design and testing performed in these types of systems. And I'm not talking "crappy" throw away cell phones but cellular basestations and switching stations. It may defy everything you know but it doesn't defy things I'm familiar with.
    There is nothing except interconnections that can fail on a solar panel, and if need be can be field repaired. On a percentage basis, its probably in the sub hundredths of one percent having a panel failure, much more likely electronics are BOS stuff

    Were the Kyocera KC-120's field repaired? Were the REC module junction box recall all repaired in the field?
    As warranties, just based on what is likely to fail, you will be changing an inverter when you have 30-40 of them on a roof every few months for free long before you will ever see a solar panel fail. I makes absolutely no sense to be worried about panels and giving the new on the block inverter company a pass. Lets have this talk again in a few years ...

    I'm not giving Enphase a pass. I still design and install mostly central string inverter based systems. I typically will do a design both ways, particularly if the location is "challenged" in some manner and let the customer decide which direction to go. I don't "sell" it to them. In fact, I always point out the higher initial costs and the risk of the relying on a 15 year warranty from a new company. Customers are driving the demand for me but I wouldn't use it if I wasn't comfortable with the product.

    It becoming very obvious, installers are not technical enough to know the difference between these products or even if they solve a real problem and be able to challenge the manufactures on their claims, neither are the customers and the company that has the best things printed get the sales. Enphase is making claims for there inverters that defy the electronics parts contained in them are capable from a durability point, doesn't matter, they can sell a few million, have an IPO and later when things start failing they will just start a new LLC with the insiders laughing all the way to the bank. 20 year prepaid for data monitoring, what a scam:roll:

    Because only single string Evergreen and SMA SunnyBoy designs will last 20 years. :roll:

    Scott.
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    Clash of the Titans!
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    Hi Scott,

    Having a Phd now that's an impressive feat. If you believe SMPS can handle being subject to daily 60-70C ambient temperature swings mounted on a roof under a solar panel then proceed as you think is best. I believe the solar panels will outlast the inverters and having 30 inverters on the roof will all be replace 2-3X before you would have to go up and swap out a panel. That's allot of labor.

    On the flatness of the VI curve, you need to look at a magnified view of the VMP knee to see that a panel that is capable of 200 watts ( lets use 20volts 10 amps ) can still put out almost that at 20.5V @ 9.75 amps. You miss understood my explanation, I didn't say the lower powered panel would put out more, what I said was all the panels will be limited to the lower panels current ( lets say 20volts @ 9.75 amps for the lower tolerance panel), the 200 watt panel will run at the lower current but at a higher voltage ... this is why single string performance is not typically effected by the panel tolerances

    I'll go and look at the test data on the CEC, last I looked was the manufacture supplied data which as I recall didn't show detailed voltage vs efficiency curves

    On Average Strings , last I looked there were other manufactures that had 12V panels in the high wattage class ( 190watt + ) ... I have 70 Evergreens on my roof, no issues and all single strings.

    There are transformer less GT inverters near 97% , power one I think was one of them, SMA you mention is the older design and all manufactures will be offering the transformer less as NEC2008 now allows this and its been in Europe for some time

    Hope your system performs as you wish and regardless of the technologies you choose welcome to owning a PV system, I have 14kw on my home

    SG
  • solarvicsolarvic Solar Expert Posts: 1,060 ✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey
    And with regards to who cares about a solar manufacturer's financial stability and it's ability to honor a long term warranty...I care. Since I'm putting my reputation and financial stability on the line when giving 5 - 10 year system warranties on an installation. A panel working today is immaterial to the concern about a panel having an issue 8 years down the line and there being no recourse because the manufacturer is no longer in business. Yes they make a quality product. Yes the likelihood of having an issue with the panel long term is very low. But that's also true of other manufacturers; ones in better financial shape. Evergreen may or may not survive, I don't know and neither do you. Is it really such a "rare" event for companies, even big companies, to go out of business?

    Scott.
    So what good is a warranty if 1 panel in your string goes bad and you can,t replace it because that model went obsolete? Are you going to replace the whole string or just mismatch it with something as close as you can find? I have had that problem already when I wanted to get more panels of the same linage. S:Dlarvic
  • solarteksolartek Solar Expert Posts: 69 ✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey

    Solar Guppy,

    We will just have to "agree" to disagree on the long term prospects of the Enphase micro-inverters. Only time will tell. I'm just surprised you believe the ambient temperature swing where the micro-inverters are typically installed (under the modules) is anywhere near 60-70C. I actually went out and did some spot temperature measurements on the first Enphase based array I installed here in Central Florida in August and I just didn't see that kind of ambient temperature change over the course of a very hot day in August. Granted it was just one (hot) summer day in Orlando. What I saw was in line with the white paper Enphase published on an installation in Palm Spring, CA. The paper can be found here.

    The CEC data I cited for SMA was off of their data sheet for one of their new generation(HF transformless) inverters, not one of their older ones. You can find that data sheet here. It doesn't look like performance data has been posted yet at the California Solar Initiative (CSI) website for these inverters. Detailed voltage versus efficiency curves for several inverters can be found here. Some Power One inverters do have higher CEC efficiencies: 96%.

    Beyond the systems my company designs and installs, I do have 2 personal solar electric systems: 3.5KW (Suntech 175-Xantrex) on my home and a smaller 1.4kW (Suntech 175-Xantrex) on my detached garage. When I designed and installed these systems I had already evaluated the first generation Enphase micro-inverters and was not satisfied with their plastic packaging and their tare losses. And given I had near ideal installation locations (both roofs facing due South, 8/12 pitch, no shading issues) relatively tight module power tolerances (-3% / + 3%) the Enphase micro-inverters were not the most financially efficient choice. The second generation versions are a significant improvement and after talking with Enphase engineers and reviewing the accelerated lifetime testing methodology I decided to start offering them as an option for system designs and installations.

    Anyways, I appreciate your good wishes. While it may not be readily apparent in this thread I have great respect for your contribution in this forum as well as your own forums and always carefully consider the content of your posts. Particularly the technical ones.

    Scott.
  • solarteksolartek Solar Expert Posts: 69 ✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey
    solarvic wrote: »
    So what good is a warranty if 1 panel in your string goes bad and you can,t replace it because that model went obsolete? Are you going to replace the whole string or just mismatch it with something as close as you can find? I have had that problem already when I wanted to get more panels of the same linage. S:Dlarvic

    Solarvic,

    One thing I (and my partners) have decided to do as a company is maintain a warranty reserve account specifically for funding the purchase a small inventory of any modules that we have installed, that are still under our warranty, and get discontinued. So far, we have not had to purchase any modules yet for this purpose. We will probably do the same for micro-inverters if the newer generations turn out to not be compatible with the ones we have installed so far.

    Your question also points out one of the additional, possible advantages of a micro-inverter system The module's electrical characteristics don't have to match.

    Scott.
  • solarvicsolarvic Solar Expert Posts: 1,060 ✭✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey
    solartek wrote: »
    Solarvic,

    One thing I (and my partners) have decided to do as a company is maintain a warranty reserve account specifically for funding the purchase a small inventory of any modules that we have installed, that are still under our warranty, and get discontinued. So far, we have not had to purchase any modules yet for this purpose. We will probably do the same for micro-inverters if the newer generations turn out to not be compatible with the ones we have installed so far.

    Your question also points out one of the additional, possible advantages of a micro-inverter system The module's electrical characteristics don't have to match.

    Scott.
    That is an issue I hadn,t thought of. S:Dlarvic
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: 7-10kW Grid Tied System in New Jersey
    solartek wrote: »
    Solar Guppy,

    We will just have to "agree" to disagree on the long term prospects of the Enphase micro-inverters. Only time will tell. I'm just surprised you believe the ambient temperature swing where the micro-inverters are typically installed (under the modules) is anywhere near 60-70C. I actually went out and did some spot temperature measurements on the first Enphase based array I installed here in Central Florida in August and I just didn't see that kind of ambient temperature change over the course of a very hot day in August. Granted it was just one (hot) summer day in Orlando.
    Scott.

    Actually, summer is probably the most temperate time of year for us in central Florida , its the time with the low humidity that gets the big swings. Panels are getting over 55C and the lows about 5C just the other day ( I have both temp and isonolation on my SW arrays), but yes, your right I was thinking peak temperature, not the delta. I also wasn't aware of a second gen on the Enphase.

    There is clearly an interest in the Enphase and I'll be the first to admit that I may fail to see what other see in a product. I have no dog in this hunt so we shall see what happens, I'll be more open to the concept with a few years data to backup some Freeze and Bake testing, I have a somewhat jaded view in seeing products released that didn't meet the hype, so I end this with that thought.
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