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Options for Grid-Tie Inverters w/limiting
#1
I'm currently in the early stages of planning a small solar set-up as a proof of concept to see if designing/building a larger system (possibly including a powerwall) is worthwhile in my current location.  

Right now I'm planning to have 4-5 solar panels with a grid-tie inverter (probably around 1000w total).  I'm in the USA in a location that makes it very difficult (expensive) to sell back to the grid so I'm stuck looking at GTI's that have limiters... Which brings me to my main question:  Where are they?  I've primarily seen 1 brand that's available and it's the SUN/ECO/Generic named blue box that everyone seems to be using.  Model numbers similar to SUN-1000GTIL2-LCD.  

Is SUN the only real player in the game right now for small systems?  eBay seems to have some larger/more expensive models from "Tumo-Int" but I haven't seen much about these in use and they're well above what I'd like to spend on a POC.  

Am I missing something?  Not searching on the right terms?  Or are the GTIL's just not as popular as it seems like they should be?
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#2
Just a legal question that i feel i need to ask.
Is it even legal in your area to hook up a grid-tie unit to the grid? In most cases its not without permit. No matter if you sell or not.
GTIL is generally not allowed in many places at all but people tend to use them. In my area they are for sure not allowed.
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#3
It's a good question, and like anything else technology related (specifically talking about the limiting part of a GTIL) the codes and regulations are always a bit behind the times.

Is someone going to come throw me in jail for using a GTIL? No. Could I potentially get fined by the power company if I'm back-feeding into the grind without paying them to let me do it? Could local code-enforcement come tell me I need to remove the solar panels because they were installed on my roof without a permit? Sure, those potentials are always there.

On a broader discussion I think we can all agree that most DIY types have done work "Illegally" by not getting a permit. In my experience most urban/suburban places in the USA don't let you do much of anything without someone else saying it's ok. Electrical, plumbing, new patio in the back yard? Yep - Get a permit. Is it strictly enforced? Not usually unless it's highly visible or someone else complains. I can't even build a small shed on my property without a zoning permit...

But - for sake of this project and specifically talking about the inverter, It's a grey area for me. There are no local codes (that I could find) strictly prohibiting the use of GTIL's. GTI's are't allowed by the power company without going through their application, design and permitting process but again, nothing specifically about GTIL's. The limiting part is why it's a grey area in my mind, nothing I'm doing will ever leave my house. Technically do GTIL's fall under the same regulations as GTI's? Probably, but there's an argument to be made that they don't. Obviously this is an entirely different discussion if we were talking about a normal GTI for which there's no question are illegal w/out the power-company's sign-off.

I'm planning to follow all the normal/official rules and codes for installing solar panels as well as some additional safety measures that have been talked about here to make sure everything is as safe as can be. But if a panel falls off the roof and lands on the neighbor's dog, I fully understand I'll be liable for that.


Having said all that - My official public stance is YES... Everyone should follow, to the letter, all local laws, codes and regulations they're governed by and have a licensed, trained and insured professional do any and all work. Don't buy or use anything not UL listed and wear a condom at all times.
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#4
Not many grid tie options with limiter, some limit in settings, some use limiter clamps..I’ve heard that the inverters that u limit in the settings are not as good at limiting. The gtil2 Tfl can have higher voltage inputs (many panels in series). The blue gtils run on lower voltage inputs and can run off of batteries due to this...u just gotta figure out what u want
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#5
Anything connected to home wiring needs to be UL-listed / tested by a NRTL like ETL, etc. Specifically it's UL1741 for all home inverters, whether grid-tied for net metering, grid-tied and limited, or even off-grid believe it or not. ETL certification is why a 8kW Aims Off-Grid inverter costs $400 more than the 10kW Aims Off-Grid inverter despite having lower output. UL1547 comes into play if you are tied into the grid whether you are exporting or not. If you expect to get a permit, your AHJ will require an NRTL certificate.

And you are correct about selective-enforcement. Almost a year ago, I was forced to take down my ground-mount solar, and to-date, no other code violations by my neighbors have been cited by code-enforcement even though they are pretty obvious, like non-permitted sheds on easements, unpermitted home additions, and irrigation systems without a backflow preventer, etc.

TLDR: GTIL's fall under GTIs because they are tied to the grid. UL1547, UL1741, and NEC Article 690.
Formerly known as Dallski
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#6
Generally i wold say the legal part is one of the smaller parts for grid tie but the concern i generally have is using grid-tie systems perhaps not approved, informed or even faulty units on the grid where potentially a line-worker come and do work.
If they dont know about the install and it is faulty or something happen they could potentially get hurt.

So now lets leave that because no one want to hear it Tongue

I would say they are not as popular because they are DIY and generally not legal. Thats the reason no one sells them where I live as example.

Many sellers in Sweden actually had to remove huge amount of inverters some time ago due to regulations and suddenly the market was very low and the ones left was expensive.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#7
Aside from testing certificates, the big difference I've seen between certified and non-certified Grid Tie Inverters is the delay in time when reconnecting to the grid. The non-certified ones will start exporting power the second they detect grid voltage, while the certified ones have a 5 minute wait period before exporting after a grid-down scenario. All grid tie inverters have anti-islanding by their very nature - they operate by sensing grid voltage and inverting DC into AC at a slightly higher voltage than the grid voltage they sense. If the grid goes down, they can't sense a voltage in their range of operation and cease producing power. The real danger to linemen is from off-grid equipment - Generators and inverters that create voltage independent of the grid. When connected to the grid in a grid-down scenario, they create voltage on the demand side of a power line that shouldn't be there.
Formerly known as Dallski
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#8
(08-28-2019, 02:21 AM)Generic Wrote: Anything connected to home wiring needs to be UL-listed / tested by a NRTL like ETL, etc.

Can you cite your source for the UL/ETL/etc requirement for any device plugged into house power?  As far as I've been able to tell (happy to be proven wrong here) there's no hard requirement for a UL stamp or any formal testing/certificate in the USA.  It's highly recommended and generally the the de facto safety standard but there's nothing stating that I'm only allowed to use UL listed devices. Don't get me wrong, I think UL testing is necessary for the masses and am glad it's the accepted standard around safety but in the end it's up to me as the end user to know what I'm using and to do it safely.

I do agree that a certification of some kind will be required to get a permit and approval from the power company, but it's not a blanket requirement across anything that gets plugged into home wiring.

I completely get the concern with back-feeding the grid in the event of a power outage.  The last thing I would want is for someone to get hurt because a GTI didn't properly anti-island itself which is why I'm also planning an under/over voltage relay as a secondary shut-off in the event grid power is lost as well as a timer to make sure power is stable before starting back up... But those devices probably won't be UL listed either ...  Rolleyes


This is a good discussion though I'm still surprised GTIL's are so much less prevalent than a cheap/simple GTI considering all the issues that come with back-feeding the grid.
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#9
(08-28-2019, 03:45 PM)ad8mustanggt Wrote: This is a good discussion though I'm still surprised GTIL's are so much less prevalent than a cheap/simple GTI considering all the issues that come with back-feeding the grid.

Maybe you should have a look at the south african powerforum The Africans down there are mostly not allowed to feed back into the grid so they use a lot of GTIL but also power diversion solutions that can help you out as well. And yeah, where a condom in Africa as well! Smile
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#10
Lmao...for me tho just don’t backfeed and use gtil, regardless of any certification. Many of the inverters are certified in other countries. If someones house burns down it’s most likely due to improper installation. If e-company knocks on my door I don’t have to let them in.. If they want to shut my power off then I’ll go full offgrid then they get no money from me..
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