Micro grid tied inverters on E-bay

Seems like a few companys are making small microsine type inverters and selling them on e-bay. One is a "Envirotech's SSI-200W Grid Tie inverter solar" and the other is a "SWEA 250 WATT GRID TIE INVERTER ". They are not UL listed but either was the TRACE or NKF unit. Has anyone had any dealings with these units? They are tempting for an entry level PV system.

Regards/John

Can anyone recommend a Grid tied inverter in the < 1000 Watt area. I am looking at the SB700u, but its over $1000. Is there any good website to look for used inverters such as the SB700u?

Comments

  • BB.BB. Super Moderators Posts: 26,870 admin
    Re: Micro grid tied inverters on E-bay

    The regulations have changed over the years... My Xantrex GT 3.0 from 3 years ago no longer complies, and, I assume, when it eventually fails, I will have to replace it with the new conforming unit (with the regulations at that time).

    People do go "gorilla solar"... What to say. Many probably do it, some may even do it relatively safely. Depending on what is installed, how it is installed, local weather conditions--lightning, windstorms, fire code, etc. all can cause risks/damage/interfere with resale of a home/insurance issues, and such.

    Is is cost effective--probably not. Small systems tend to cost more per kWhr generated vs larger systems.

    You probably all ready have read the thread regarding the SWEA here.

    Somebody on the SolarPowerForum purchased a couple of the SWEA units... One worked for awhile, another was apparently DOA.

    There have been other vendors that have done the "one inverter per panel" thing before... Looks like the Enphase Micro-Inverter M175-24-240-S02 may be real (says UL listed on their website).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Micro grid tied inverters on E-bay

    The Enphase units are UL listed and about the same price - around $200. Unfortunately, availability has been a problem, which is why we have not listed most of them yet.

    They are supposed to be coming out with a 225 watt unit, but no word on it yet.

    Personally, I would not touch any of the eBay type ones, like the SWEA.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay

    Windsun,


    I went to the enphase site and looked at what they do. It seems like a pretty cool idea, and one that would allow people to grow a system. Is it for real, and is it likely to have an impact on the market. How is the pricing relative to current grid tie inverters?

    I assume that they wire to the panel just line a conventional inverter.

    Tony.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Micro grid tied inverters on E-bay

    Not sure how much impact it will have on the market.

    They are the first one around to have real UL/NEC/ETL approvals.

    But the catch is that they are really only cost effective for smaller systems. If you stack up about 10 of them, you have spent close to $2500 for 2000 watts of panel. For that price you could have gotten a standard grid tie inverter.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay
    Windsun wrote: »
    Not sure how much impact it will have on the market.

    They are the first one around to have real UL/NEC/ETL approvals.

    But the catch is that they are really only cost effective for smaller systems. If you stack up about 10 of them, you have spent close to $2500 for 2000 watts of panel. For that price you could have gotten a standard grid tie inverter.


    But wouldn't there be advantages in that? Assuming about the same inverter cost for say a 2kw system, wouldn't there be an advantage in having simpler DC wiring and therefore cheaper? Also if one inverter failed, the entire system would not go down, so that replacing on micro inverter as opposed to a 2 kw large inverter would be cheaper.

    Also, you could start with 1 panel/1 inverter, save your pennies, buy another next year or month or week, and build a system as you could afford it. (Permit issues not withstanding,, the headache of having separate permit/utility approval for each panel as opposed to the entire system).

    I just think it is an interesting alternative. It may not be net/net any cheaper, but it would allow way more flexibility.

    Tony
  • BrockBrock Solar Expert Posts: 629 ✭✭✭
    Re: Micro grid tied inverters on E-bay

    I would venture a guess that 10 small 250w inverters would be quite a bit less efficient than a single 2500w inverter.

    But I would agree, for someone starting small, that would be the way to go, I know my father-in-law really wants a 350w-500w range.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • Solar GuppySolar Guppy Solar Expert Posts: 1,959 ✭✭✭
    Re: Micro grid tied inverters on E-bay

    Running AC service all over a roof is no less challenging than running DC, no advantage there.

    Having the inverters on the panels will lower efficiency and likely long term reliability, the inverters will be subject to temperatures exceeding 70-80C ambient, very harmful for power electronics. FET's and especially capacitors life is diminished exponentially with heat.

    And how does one know when a single panel inverter combo has failed?, when the inverter is centrally located, one can measure voltage and current from a panel, try getting on the roof to figure that one out.

    Mating an inverter that will have life span measured in months to a panel that is measured in decades is not a wise choice and hence, why it has and will never be a commercially viable product, the economic reasons don't help the cause either.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay

    Not to be a naysayer SG, and clearly you have forgotten more about GT systems that I will ever know, but I disagree with a couple of things you said.

    First, If a component fails, it would seem that it would be just as easy to discover that there is a "shortage" with either system. If for example you had ten panels in a micro invert string, and you had been harvesting say 6 kwh/day and all of a sudden your harvest went to 5.4 you would know you had once panel or 1 inverter out. On the other hand in a conventional set up, the same would apply, assuming you had the metering to monitor. You still would have to get on the roof to id the suspect panel. I do agree that you have one more component on the roof and in the weather.

    Second, I don't think it is fair to assume that the life span of a micro inverter would be measured in months. If that were the case with this product clearly it won't fly. but assuming a real world failure rate that is comparable to a conventional inverter net/net then there really would be no advantage there either. While I agree that heat is the enemy of electronics it seems that robustness would have to be designed in.

    Finally, the advantage of not having to run high voltage DC circuits on and from the roof IS an advantage. High voltage DC breakers and disconnects are expensive relative to their AC cousins.

    I guess my real interest here is that just because one system is good doesn't mean that another system doesn't have a place. Clearly micro-inverter systems need to prove themselves, (and I am a big skeptic of most new things) but the idea does have great merit in that it would allow people to get into grid tie who might otherwise either bootleg a system, or would build a battery/hybrid system at much great expense just because they want to "get in to solar".

    Permitting issues aside, If I could build a system 1 panel/inverter at a time I might be more inclined to do so even if the pay off wasn't very good.

    It would be very interesting to build to identical systems for Beta testing. One system with 2.5 kw of panels and a conventional grid tie, the same system with the same orientation with micro-inverters. After a year compare the net numbers. Compare after 5 years. Compare repair numbers.

    Icarus

    I know that most of this is Press release stuff but interesting read:http://cleantech.com/news/2951/enphase-introduces-its-micro-inverter-system

    http://peswiki.com/index.php/Directory:Micro-Inverter_System_by_Enphase_Energy

    As for warrentee: http://www.solarindustrymag.com/e107_plugins/content/content_lt.php?content.2009 (assuming they are still around in 15 years!
  • BB.BB. Super Moderators Posts: 26,870 admin
    Re: Micro grid tied inverters on E-bay

    The Enphase product by changing power to 240 VAC has not fixed very many issues vs DC... My DC system is a higher voltage (~320 VDC) so, in theory, my voltage drop will be less (can be as high as 550 VDC) than at 240 VAC with the same wiring. I have just two strings, so I have no DC breakers/inverters to worry about for my smaller 3kW GT system.

    Also, I am not quite sure, but I worry that running 240 VAC wiring on the roof would make damage to my AC appliances a more likely possibility than running DC down a length of cable to a GT inverter mounted a distance from the panels... Typically, long wire runs tend to reduce the conduction of the higher frequency components of impulses such as lighting... I am sure I would probably still have to replace my GT inverter after a near strike--but think that the damage inside the home would be less.

    The Enphase systems includes a very nice power line based network--so figuring out a bad unit is probably pretty easy.

    I would not expect to be able to determine one inverter failed by monitoring a daily power drop... 6kW would require something like 30 200 watt inverters... That is a 3% drop in output... From watching my system (no computer logging), I would be hard pressed to notice less than a 25% loss of power. The sun+weather is just to variable to see/measure a 3% loss of output.

    I see Enphase did address an issue that I saw with another "brick" vendor--As I recall, their modules were sealed on the back of a solar panel--you had to replace both if there was a failure in either. A pretty costly "repair".

    Lastly, I am not at all sure about the inverter's lifetime... They talk about 119 years between failures (MTBF). Mounting on a hot roof, power electronics, and trying to hermetically seal the units against moisture (case splits, wire acces, even moisture up the wire strands themselves) is tough in a dramatically thermal cycling environment (below freezing at night, probably above 150F during the day).

    Even if they get the sealing done right... For every 10C rise, the life of the electronics typically falls by a 1/2... Just mounting on the roof instead of down below in shade with air flow--life would be impacted by 1/2*1/2=1/4, or a 75% reduction in life if the units run 20C (36F) higher because of their location.

    And, if I had the choice of 20 inverters on the roof or one on the ground--I would pick the 1 on the ground because it is easier to replace. And, overall, I believe I will be replacing hand fulls of inverters on the roof in the time I am installing my 3rd inverter on the ground.

    One thing to remember about MTBF vs Life... I can have a set of 4 tires on my car and get 50,000 miles out of them before I need to replace them... And, I normally don't expect any flats (from tire Mfg's failures--I drive over a board with nails, my fault), but lets say I get one flat/tire failure in 50,000 miles for the sake of argument.

    MTBF = 4x50,000miles for 1 failure = 200,000 miles mean time between failure
    Life = 50,000 miles (tread life)

    However, I cannot expect more than 50,000 miles out of my tires before the tread is worn down and they need replacement... So every 50,000 miles, I will need to change all four tires even if the MTBF is 200,000 miles or more.

    So, while the inverters are less than 10-5 year old:

    MTBF=119 years/10years=11.9 years average to first replacement

    It is possible by the time I get to 20 years, that, at least 50% of the inverter bricks (making up a sort of plausible number without any data to back it up) will have needed replacement. And if technology has changed in that time (UL/NEC rules, networking hardware/software, brick sizes/function, vendor gone missing, or something else)--I may be left with figuring out the costs to upgrade the rest of the 20, plus the networking and wiring--with most of the work done on a 2nd story roof.

    In general--I would prefer to keep the complex stuff near the ground, shielded from sun/rain, and easy to service. Could I be wrong in my assessment--yep... Just my 2 cents worth.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Micro grid tied inverters on E-bay

    Like to add one tidbit of info. Some of us need to look under the hood of a 2000 or newer car. There is loads of electronics there. My jeep has 3 computers in the engine compartment. They see 10 to 200+ F, heat, water and vibration. Most of them will last 10+ years. If the, we need a handout, car makers can make durable electronics, the anyone can, if they plan on doing it right and not cut corners.
  • nigtomdawnigtomdaw Solar Expert Posts: 705
    Re: Micro grid tied inverters on E-bay

    Most auto manufcturers locate there black boxes (mapping systems/computers) within the vehicle not the engine bays , usually underdash or below seating, at least the reliable ones do, why put you expensive blackbox in the engine bay subject to extreme temps and humidity/moisture when it can sit cosy and dry next to the glove box. Usually only sender units, potentiometers and tranducers live in the engine bay and these have the highest failure rates.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay

    Bill, Neil.

    I think you should split this thread. I think the el-cheapo bootleg e-bay inverters are a different discussion that the UL listed Enphase system. I think both threads merit discussion, but we may loose the question(s) in the answer(s)

    Tony
  • BB.BB. Super Moderators Posts: 26,870 admin
    Re: Micro grid tied inverters on E-bay

    Tony,

    The best I can see here would be to start a second thread and copy the Enphase information over to its own thread (and Enphase title)--but even the opening post mixed the two topics pretty well.

    Do you (or others) see a lot more to discuss about the Enphase at this time?

    Feel free to discuss here--I can always delete the discussion posts (including this one) when we have decided.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay

    Bill,
    I don't have really anything to add at this point. Fundamentally, I think that the discussion about "E-bay specials" is one that we have had quite often on this site and had it's own relevance.

    The Enphase system at least has the legitimacy of UL and the fact that they seem to be shipping. Whether or not folks here think it is a good idea or not is also relevant. I would worry that because of the Enphase IS a product that can be used legally I don't think it should be lumped in with those inverters that can't.

    Tony
  • BB.BB. Super Moderators Posts: 26,870 admin
    Re: Micro grid tied inverters on E-bay

    I am going to leave this thread as it it... I will create another post with a title about Enphase and a post pointing this this thread...

    Even though this thread started about Ebay Inverters, the very next post pretty much hijacked this thread to be about Enphase instead (sorry--that was me).
    n3qik wrote: »
    ...My jeep has 3 computers in the engine compartment. They see 10 to 200+ F, heat, water and vibration. Most of them will last 10+ years. If the, we need a handout, car makers can make durable electronics, the anyone can, if they plan on doing it right and not cut corners.

    Actually, while automotive designing and building reliable automotive electronics is not a walk in the park--The actual life is not nearly as long as one would think...

    For example, you can use ~35 MPH as the long term average to convert to run time hours (I have over 50,000 miles on a GPS, and the moving average is ~31 MPH for a car that spends much of its time in the SF Peninsula and local freeway driving).

    Assume 15,000 miles per year * 10 years = 150,000 miles

    150,000 miles / 35 mph = 4,286 hours of operation

    4,286 hours / 10 hours per day (rough average "on time" for my GT System) = 429 days

    429 days--I would not be too happy if my inverter lasted 1-2 years. I probably would be thrilled if my car's computers/wiring lasted 300,000 miles.

    Or another way to look at aging, I see thermal cycles as a major factor for failures... Assume that a car starts/stops ~2 times per day and a solar inverter cycles 1 times per day

    That could be, roughly, equivalent to 20 years of GT inverter life vs a 10 year car life--not bad at all.

    Which is the correct way to look at GT Inverter vs Car Electronics in terms of lifetime? Not sure, both have valid points.

    Nigtomdaw's observation that not many electronics live bolted to the motor, but in the passenger department instead is a good point.

    Using that observation, then the GT Roof Top Inverter environment is probably a tougher one that a car (excluding vibration).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Micro grid tied inverters on E-bay

    The SWEA 250 watt system is close to UL approval, I have received the draft copies of the specs to proof in English, they consider UL approval that close. If you check about on the internet you will find that SWEA really stands behind their product, I know I am a distributor but their commitment to their product has really impressed me over the years.

    Personally I am more interested in the 1KW stacked version of the inverter being UL approved for the 1kW wind turbine. Right now for UL required installations we do not have a real product for that market as we start at 2kW with the SWA products.

    For those who are unaware, SWEA is best known for its wind products which is what my company is heavily committed to marketing. I have sold many of these little SWEA 250watt inverters and usually to the person who wants to start small without a huge capital outlay. Of course all these small inverters that I have sold doesn't equal the revenue from a single 20kW wind turbine. ;)
  • emsaiemsai Registered Users Posts: 5
    Re: Micro grid tied inverters on E-bay
    Infinergy wrote: »
    The SWEA 250 watt system is close to UL approval, I have received the draft copies of the specs to proof in English, they consider UL approval that close. If you check about on the internet you will find that SWEA really stands behind their product, I know I am a distributor but their commitment to their product has really impressed me over the years.

    Personally I am more interested in the 1KW stacked version of the inverter being UL approved for the 1kW wind turbine. Right now for UL required installations we do not have a real product for that market as we start at 2kW with the SWA products.

    For those who are unaware, SWEA is best known for its wind products which is what my company is heavily committed to marketing. I have sold many of these little SWEA 250watt inverters and usually to the person who wants to start small without a huge capital outlay. Of course all these small inverters that I have sold doesn't equal the revenue from a single 20kW wind turbine. ;)

    I am interested in buying an SWEA Wind starter kit with one extension, but have been reluctant to do so because I am not sure of their quality, cutsomer service and warranty. I have had one SWEA distributor tell me that they stopped selling these units because of "failures in the field." I had a bad experience with an EnviroTechs SSI 200 and do not want a repeat. emsai38@gmail.com
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay

    Can you spell 10' pole?

    Seems to combine the worst of all worlds,, non UL listing, "Ebay" product, and small scale wind! Couldn't get worse IMHO!

    Tony

    PS. I still see no follow up to the "close to UL listing" previously mentioned.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay

    emsai,
    there is not a need for you to give your email address out for the whole world to see as you may use the pm feature in this forum to contact another member directly. then if you wish for them to have your email you could give it to them.
  • mike95490mike95490 Solar Expert Posts: 7,307 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay

    here's another new hint about solders and "tin pest". Many lead-free solders, are prone to tin whiskers and "tin pest". Tin undergoes a non-whisker event, when cooled below 0 C. It turns to powder. A few freezing cycles will strain the inverters integrity, if extra special solders (or old style 60/40 tin lead) is not used.

    http://en.wikipedia.org/wiki/Tin_pest
    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 ,

  • emsaiemsai Registered Users Posts: 5
    Re: Micro grid tied inverters on E-bay
    niel wrote: »
    emsai,
    there is not a need for you to give your email address out for the whole world to see as you may use the pm feature in this forum to contact another member directly. then if you wish for them to have your email you could give it to them.

    ok. Did not want to clutter the thread. Thanks.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Micro grid tied inverters on E-bay
    emsai wrote: »
    ok. Did not want to clutter the thread. Thanks.


    i never said you cluttered anything and i don't care if you do give your email address if you want to as i was merely making sure you were aware you didn't have to in order to get somebody to contact you or visa versa.
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