small Grid Tie inverters comparaison

Hi guys,

I'm looking into make a small grid tie solar system.
I would like to find the best inverter available.

That's what I found:
Envirotech SSI-200W, SWEA UWT-I-250 and Enphase.

What would be the best choice for me.
I like Enphase iverter but it is 240V output, I would prefer 120V.
SWEA seem to be an interesting choice any comment?
Enrinotech is interesting too but the input voltage is low.

Can some one comment those inverters for me.
Because buying on ebay seems to me as a blind purchase.
Thank you

Comments

  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: small Grid Tie inverters comparaison

    Please,, please do a search on this site about small grid tie inverters. Of the three you mentioned, ONLY the Enphase is a legal, UL/CE listed product. The other are off shore, no labeled, not legal, perhaps not safe to install products!

    Installing one of these type inverters puts you and your building at risk, and could potentially buy you a ton of liability with the utility.

    Tony

    PS there are numerous threads on the subject, use the search function, so that we don;t have to reinvent the wheel.
  • BB.BB. Super Moderators, Administrators Posts: 31,688 admin
    Re: small Grid Tie inverters comparaison

    Here are two threads:

    Micro grid tied inverters on E-bay
    Enphase

    For those trying to search here--I do empathize with you... I remember specific threads and I have a heck of a time finding them. It is not easy for somebody brand new to this board.

    However, if you have specific names/model numbers--usually, it is pretty easy to find.

    You can also use Google, and after the search terms, type in (without the quotes) "site:www.wind-sun.com" and you can find things that the forum search will miss (limited to searchs on the wind-sun forum).

    I.e., "BZ" is a common search here to find out about that controller and its issues. "BZ" in the forum search will not return anything. Google:

    BZ site:www.wind-sun.com

    will find lots of threads/posts.

    Short answer is the Ebay products have hit and miss reliability, and questionable safety. And, they are not legal to use in the US (or probably Canada).

    Also, if you "run the numbers" and want to use these to save money--will never happen. Small systems tend to be expensive to construct. Larger systems, you get volume pricing and installation that can make these systems more cost effective--plus the "real" systems can be eligible for government and local rebates/credits/etc.

    See dsireusa.org for nation wide and state by state program summarys for energy conservation kickbacks and laws.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: small Grid Tie inverters comparaison

    Thank you for answer Bill and Tony.
    Indeed I red all the articles regarding this subject.

    There all personal opinions no real arguments.
    Except maybe UL approval witch apply to US I'm from Canada Quebec.
    There is nothing of complicated in the system. The frequency has to be 60hz, voltage in phase with the main and the low THD. That is it.

    I was hoping to hear some news from people who bought those products.
    I'm not ready to spend 5-10k and more on a solar system of few kW.
    I would like to start by smaller one and spend 1k make some test play with it...
    Than I can use my panel + buy some more and a decent inverter.
    I will lose only 200$ for this inverter.

    I want to be able to move my system from one place to anther. I want show it to other people to uncourage them.

    Those small grid tie inverters should be a perfect choice for my application.
    I should maybe ask my local electricity provider if such system is acceptable.
    I even can analyze it myself with a power analyzer.
  • BB.BB. Super Moderators, Administrators Posts: 31,688 admin
    Re: small Grid Tie inverters comparaison

    pitskalov,

    I am not sure--did you have a question?

    One of the links I provided did have a personal use story about the SWEA product (out of three, two where DOA, and the first one failed when trying to swap a chip with one of the other DOA's).

    The Enphase appears to be a "real" unit--but it is only available as a 208/240 VAC unit... You would probably need a transformer to convert to 120 VAC.

    There is a SunnyBoy 700 watt unit out there [edit: remove comment about availability issues. -Bill]. Problem is that it costs $2 per watt, whereas a SunnyBoy 7,000 watt unit cost about $0.57 per watt...

    Other than the 208/240 VAC output--the Enphase appears to be the only cost effective and legal small GT inverter out there.

    By the way, what kind of Power Analyzer do you have/planning on using? I have an electronic Utility Meter that has quite a few power analysis function internally (watts, current, power factor, distortion, phase angles, etc.). With my 3kW GT system (Xantrex)--the readings are pretty boring (PF equals unity, distortion is low, more sun, more watts, less sun, less watts).

    I am a system design engineer--even I lost interest in the details pretty quickly. :roll:

    -Bill

    PS: By the way, I probably need to correct the above 700 watt SunnyBoy comment... I think I confused availability problems with the 700 Watt WindyBoy (which appears to be difficult to get)... The SunnyBoy should be no problem (that I have heard--I am not in the "business").
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: small Grid Tie inverters comparaison

    Pit,

    I do understand your desire to, start small, be portable, etc. The answer to that question would then be the Enphase. The problem with the Ebay specials is the reason they are not UL/CE listed. My guess is that they are not listed because they are, in their basic design either not reliable or not safe,,, or both.

    It is one thing to say that you don't care about UL/CE, but once you plug into a public utility there is the potential to do damage to others, or other's property. While I am a big fan of "asking forgiveness rather than permission", I do believe that I have a responsibility for others once I cross the line of others property.

    Tony
  • EcnerwalEcnerwal Solar Expert Posts: 101 ✭✭
    Re: small Grid Tie inverters comparaison
    pitskalov wrote: »
    Except maybe UL approval witch apply to US I'm from Canada Quebec.

    Then you had better have a system which is CSA rated (at minimum), if you plan to connect to the utility. Canada is not some unregulated backwater; unrated Chinese junk is unrated Chinese junk, on either side of the border. In point of fact, I vaguely recall DJ (I don't think he's on this board, but he's on both usenet and the Outback forums from time to time) making comments that PQ had somewhat stricter than average requirements regarding who could work on generating systems attached to the power mains, so you might want to check your facts a bit before you get yourself in big trouble...
  • BB.BB. Super Moderators, Administrators Posts: 31,688 admin
    Re: small Grid Tie inverters comparaison

    From what I have seen over the years, Quebec- (Hydro Quebec?) has held their power connections to a pretty high regulatory level...

    And, UL/CSA/etc. NRTL's (National Registered Testing Laboratories) have been signed into a common regulatory plan. So, UL (or cUL) and CSA, ETL, TUV, etc. all pretty apply cross boarders (they test and list to the same regulations--with some countries having specific requirements for their local needs). Usually, these are implemented on the local level by buidling laws (typically on city / county level in the US--And from the Power Agency level; it appeared to me; for Quebec).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: small Grid Tie inverters comparaison

    Thank you again for your answers,

    It really helps me, because the people who sell products don't give you any advices. It is normal they want sell their staff, so I really appreciate your help.

    You were right Bill about Swae I didn't really consider that one.
    I was more interested by Enirotech (120V!!!) and mostly Enphase.
    FYI Bill, I was planing to use Voltech power analyzer. I want to borrow it from my job.

    No, I don't really want a pollute HQ grid. You are right HQ is trying to keep it as clean as possible. But lets be realist a 200W system wont do much damage to HQ network.
    I pretty sure that the new Compact fluorescent lamp are 10 times more damageable than my 200W solar inverter.

    So this being said I wasn't thinking to install anything before advising and getting a permission from HQ for my installation.
    I agree 100% with you that CSA approval would be a huge help, but still maybe I can overcome if simply HQ give me their approval.
    I work a lot with HQ so maybe I can have some help.
  • BB.BB. Super Moderators, Administrators Posts: 31,688 admin
    Re: small Grid Tie inverters comparaison

    pitskalov,

    You are very welcome--we all try to help here. And, sometimes, even provide actual answers. :roll:

    I agree that the CFL's are many times worse than the typical GT inverter with respect to noise/issues on the power line...

    Normally, the two issues with the power company are is the Inverter NRTL approved and is it installed per the building code. And second, how is the billing going to work (net metering, buy back, ignore, block meter from turning backwards, or whatever).

    With the power analyzer--just asking--are you doing an evaluation as a possible followup purchase? Are you going to get an "EMU" to monitor the inverter--or purchase some sort of kWhr meter so you can be sure that it is still working over time?

    200 watts of solar is not going to save you any money--especially in a region known for "cheap" power ($0.10 per kWhr or less?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: small Grid Tie inverters comparaison

    your help is very appreciated,

    Here in Quebec the government doesn't provide any help for solar installation.
    Therefore they connect you to the grid for 400$ can. The give you a special meter.
    So you can get credited for extra kWh but I don't think it is going to happen with my 200W system :)

    I just verified the Enphase inverter seems to be CSA aproved: UL1741/IEEE1547
    FCC Part 15 Class B. I will contact HQ just to be sure.

    Enphase give a 15years warranty !!! Impressive.

    With my power analyzer I want test the efficiency, TDH, power produce...
    I'm not sure I can measure the energy, it is an old one!
    I want make few tests, I'm electrical engineer (jr) so it is fun.
    I don't plan to make any money with this system.

    I'm thinking to buy solar panels from China, is it worth? It is cheaper.
    I will buy 1 sample and test it as much as possible and see if it is worth to have business with them.
  • BB.BB. Super Moderators, Administrators Posts: 31,688 admin
    Re: small Grid Tie inverters comparaison

    Don't know about the Chinese panels... Everything is made over there now--so they can make things well--if needed.

    But, as the panel fire thread shows... You can also get dangerous stuff from there too--if you are not careful. (stay away from plastic covered panels--stick with glass for any "large" arrays).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: small Grid Tie inverters comparaison

    i don't know about all with plastic as the unisolars never had that problem of catching fire. they do have other issues, but catching fire isn't one of them.;)
  • BB.BB. Super Moderators, Administrators Posts: 31,688 admin
    Re: small Grid Tie inverters comparaison

    The Unisolar has a metal backing and the top plastic (?) is very thin. And it is UL Listed...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: small Grid Tie inverters comparaison

    it is like a bunch of small bubbles and i'm not sure why. i have mentioned this rough surface while responding to n3qik because it catches and holds snow sooner and longer than other flat pv surfaces would. side by side comparison would be interesting for snow and ice.
    also, i don't believe they are making the unisolar brand pvs in china as of yet. if memory serves they are still in michigan.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: small Grid Tie inverters comparaison

    Unisolar framed panels where made in Mexico. Now all they make are the building intragrated stuff at 3X the price per watt. not sure where.

    For ice/snow, panels where cleared in one day, so a non-issuer for me. Plus if the ice is real thick, I can take a rubber hammer and knock off the ice unlike a glassed panel.
  • System2System2 Posts: 6,290 admin
    Re: small Grid Tie inverters comparaison
    icarus wrote: »
    Please,, please do a search on this site about small grid tie inverters. Of the three you mentioned, ONLY the Enphase is a legal, UL/CE listed product. The other are off shore, no labeled, not legal, perhaps not safe to install products!

    Installing one of these type inverters puts you and your building at risk, and could potentially buy you a ton of liability with the utility.

    Tony

    PS there are numerous threads on the subject, use the search function, so that we don;t have to reinvent the wheel.

    I highly advise you to get your stories right.

    UL does not equal LEGAL or imply that the product without UL approval is UNSAFE.

    The SWEA 250 watt inverter has gone through testing by the EU which is as tough or tougher than any testing here in the US.

    The 250 Watt SWEA system is close to UL approval anyway (I have reviewed drafts of the UL documents so I know its very close), but since it plugs into the home outlet many states such as recent court cases in Minn have ruled the utility cannot interfere with utilization of these small wattage systems.
  • BB.BB. Super Moderators, Administrators Posts: 31,688 admin
    Re: small Grid Tie inverters comparaison

    Infinergy,

    Welcome to the forum!

    Regarding the legal cases on small grid tie attachments in Minnesota... Do you have any links to articles/rulings from the courts?

    About NRTL Listed devices--have not many/most cities/jurisdictions in the US incorporated some version of the NEC into their codes which require competent NRTL Listings?

    And I always read that plug-in GT type inverters would never be allowed in the because of the issue with how wiring safety would be compromised by having multiple energy sources introduced into home wiring... Example, put a 15 amp fuse on one end of the wire (~1,800 watts) and install some "plug-in" GT inverters in another 15-20 amp rated outlet (say ~1,000 watts of solar panels or 4 inverters rated at ~8.3 amps). Now, somebody plugs loads into another wall outlet and that will now be powered by ~23.5 amps (15 amp breaker + 8.3 amps of GT inverter)... Well over the NEC ratings of a 14 awg branch circuit and typical wall outlet.

    In England, with their "ring" supplied power and a fuse required in every plug--I guess it would be a bit less of an issue--but I could still see problems.

    How would the courts be able to override NEC and safety concerns--let alone a regulated utility's requirements (typically approved through the state's PUC)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: small Grid Tie inverters comparaison

    I have asked our SWEA dealer in Minnesota to re-email me the citations on this matter.

    The amp rating of the circuit is a valid point and creating an overload in a house would be the same concern as with the improper installation of any electrical appliances in the home. 1kw is the maximum recommendation from SWEA for this very reason.

    From my many conversations with representatives at Oncor / TU electric, the real concern from the utilities concerns line safety when the grid is down. They do not want someone's solar system or wind turbine sending significant voltage down the line and endangering a linesman working on downed lines. My friend at TU Electric's comment on a 250 Watt plug in was "Who Cares, its totally insignificant !".

    By the way, the SWEA unit has the standard safety shutdowns when the grid is down, we test this on every unit from our test bench before shipping them out.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: small Grid Tie inverters comparaison

    "My friend at TU Electric's comment on a 250 Watt plug in was "Who Cares, its totally insignificant !"."

    i would have to say that lineman isn't thinking very well then. if say in an area of 1 sq mile that are using your max of 4 of these for 1kw and it really takes off with say 4 or 5 installations that this lineman could see 4-5kw upon his who cares.:p:D
    the point is it adds up and can get significant.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: small Grid Tie inverters comparaison
    Infinergy wrote: »
    I highly advise you to get your stories right.

    UL does not equal LEGAL or imply that the product without UL approval is UNSAFE.

    The SWEA 250 watt inverter has gone through testing by the EU which is as tough or tougher than any testing here in the US.

    The 250 Watt SWEA system is close to UL approval anyway (I have reviewed drafts of the UL documents so I know its very close), but since it plugs into the home outlet many states such as recent court cases in Minn have ruled the utility cannot interfere with utilization of these small wattage systems.


    Perhaps it is a semantic distinction. My point is that in MOST cases only "listed components" can be installed in most jurisdictions. It doesn't make it a criminal or even a civil offense to do so,, but it is contrary to most codes.

    As for the safety of a non-listed component. The reality is that regardless of the safety of the component the listing assures that it meets some minimum standard for safety. If it isn't listed doesn't mean it is NOT safe,, it just means that it hasn't been tested. (May not have been tested because it can't pass!) The reality of insurance world is that if you install a non listed component and have a fire,, the chances of any insurance paying off is significantly diminished.

    I will refrain from suggesting anyone install any given product until it has some relevant testing/listing.

    Clearly you are a sales rep for the aforementioned product. As I have suggested in many threads,, I support the idea of micro inverters as a way for people to get in to PV on an affordable (If not very efficient) scale. I wish you well,, but I think you should be careful until your product does indeed get listed! I have seen too many things that are "this close" to whatever to believe most of them. In short,,, show me the beef.

    Tony
  • emsaiemsai Registered Users Posts: 5
    Re: small Grid Tie inverters comparaison
    niel wrote: »
    "My friend at TU Electric's comment on a 250 Watt plug in was "Who Cares, its totally insignificant !"."

    i would have to say that lineman isn't thinking very well then. if say in an area of 1 sq mile that are using your max of 4 of these for 1kw and it really takes off with say 4 or 5 installations that this lineman could see 4-5kw upon his who cares.:p:D
    the point is it adds up and can get significant.

    And what about the good ol' boy that cranks up his 10kw gas generator during a power outage, and back feeds it into his house with out cutting off the mains?
  • mike95490mike95490 Solar Expert Posts: 9,276 ✭✭✭✭✭
    Re: small Grid Tie inverters comparaison
    emsai wrote: »
    And what about the good ol' boy that cranks up his 10kw gas generator during a power outage, and back feeds it into his house with out cutting off the mains?

    He'll find the gen shuts right down with the whole neighborhood connected.
    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 ,

  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: small Grid Tie inverters comparaison
    icarus wrote: »
    Please,, please do a search on this site about small grid tie inverters. Of the three you mentioned, ONLY the Enphase is a legal, UL/CE listed product. The other are off shore, no labeled, not legal, perhaps not safe to install products!.

    does UL rating means no permit required?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: small Grid Tie inverters comparaison

    if by permit you mean inspection then no because they would want to be sure you connected that approved equipment correctly.
    building permits may be another matter depending on local rulings and is only a tax imho, but does also sometimes result in an inspection for proper installation.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: small Grid Tie inverters comparaison
    mshen11 wrote: »
    does UL rating means no permit required?

    No, it does not.

    It means that non UL probably cannot get a permit, period.
Sign In or Register to comment.