diy solar

diy solar

Are the MPP Solar Hybrid inverters capable of backfeed to the grid the full PV power?

Offhand, I don't know of any add-on anti-islanding device although one could be developed. An inverter implements it by driving test signals out of phase with line voltage.

Sunny Island performs anti-islanding while on-grid, taking over the function GT inverters would otherwise have done. But it is more expensive than the inverters you're trying to adapt.

Someone on another forum proposed just a relay powered by line voltage:


That won't work, because it will remain connected during islanding. It would only detect a severe drop in voltage (a 240V relay will stay connected below 120V)
 
Offhand, I don't know of any add-on anti-islanding device although one could be developed. An inverter implements it by driving test signals out of phase with line voltage.

Sunny Island performs anti-islanding while on-grid, taking over the function GT inverters would otherwise have done. But it is more expensive than the inverters you're trying to adapt.

Someone on another forum proposed just a relay powered by line voltage:


That won't work, because it will remain connected during islanding. It would only detect a severe drop in voltage (a 240V relay will stay connected below 120V)
Re: a possible DIY anti-islanding device: I liked the idea of "a relay powered by line voltage". I will wonder about how that idea might be made to work, ... while I also ask some local solar buddies about options too. I will share if I come up with something worthy to put on our shared brainstorming table. I remember since high school: "When there is a Will, There is a Way" ! ... Thanks for sharing link :+)
 
All that a relay powered by line voltage will do is pull in at some good fraction of full line voltage, and drop out at a considerably lower voltage.
It probably won't provide brown-out protection for low line voltage, doesn't drop out soon enough.

It will not provide anti-islanding. It will not allow safe backfeeding of the grid by a nonUL-1741 device.
Looking on Digikey, there were ICs that implement UL1741. Power devices would be required as well, to apply test current and measure impedance for those ICs.
 
I have my Grid power going into my MPP LV2424s (got 3 configured into 240vac split phase) going through 3 x 40 A breakers plus going through a couple of dc-ac SSRs mounted on Heat sinks, mounted on cement board, below the small circuit breaker box I use for my "Grid IN to All In Ones" . I use those two SSRs as an off on switch/ especially as my disconnect option, as part of my Chargery BMS8T's charge side control for cutting off my 120ac circuits IN to my All In Ones (as possible source of a grid powered battery charging cycle/ which BMS charge side trigger cut OFF. ... ( my SSR testing seems to show my dc-ac SSRs able to handle 120AC current better than my testing of MPPT controlled DC currents, or large DC battery currents./ Plus I would further test my dc-ac SSR for heating up, and voltage drop if I considered them for feeding the grid). ... If an MPP All In One can send power to the Grid, it has to be through that same circuit IN (imagine OUT would be at slightly higher voltage than in, in matched pure sin wave and phases/ not yet studied those specifics). I could see my AC circuit going through my two SSRs (one for each 240vac leg) being triggered to disconnect when there is no grid power to my house or property . Off top of my head, I could think of tapping power from part of my house that is always on grid, and wiring up some kind of relay to release my dc-ac SSRs which control live AC current IN (and Out) to my MPP All In Ones, get em release to open circuit when no grid is coming into to my property.

... I will also be looking at what options might be on the market. I recognize this arena of experimenting is in an arena concerning the personal safety of lineman who might be working on down grid lines. It is not hard to also think about possible extreme liability consequences for sending electricity into a grid lines in improper manner, especially when it was not powered by the grid owner side. Just Brainstorming here and offering Food for Brainstorming, and possible future experiments. ... while also thinking: When There is a Will, There IS A WAY ! :+) Bill
 
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Offhand, I don't know of any add-on anti-islanding device although one could be developed. An inverter implements it by driving test signals out of phase with line voltage.
Hello Hedges, i think Victron has one:

1606847865883.png
 
"Passive anti-islanding"
(Documentation of SMA inverters describes active anti-islanding)

Certificates for a number of countries, although not USA
 
Hello Hedges, i think Victron has one:

View attachment 29033
Interesting; I found a data sheet info. in English: https://www.victronenergy.com/upload/documents/Ziehl-Voltage-&-Frequency-relay-UFR1001E.pdf ... Still wondering about prices along side possible DIY test project :+)
 
Offhand, I don't know of any add-on anti-islanding device although one could be developed. An inverter implements it by driving test signals out of phase with line voltage.

Sunny Island performs anti-islanding while on-grid, taking over the function GT inverters would otherwise have done. But it is more expensive than the inverters you're trying to adapt.

Someone on another forum proposed just a relay powered by line voltage:


That won't work, because it will remain connected during islanding. It would only detect a severe drop in voltage (a 240V relay will stay connected below 120V)
That was a Super Interesting Thread from a different forum posted by Hedges .....
https://powerforum.co.za/topic/112-anti-islanding-devices/

Here's a copy of what I will be studying again / from several of those forum members/ ...

Re: for Grid Lineman Protection when Feeding Solar Power to Grid, & protecting your legal liability butt:
::: from thread entitled: Anti-Islanding devices?


Copy of a few posts:

... to really make it safe I need to add an anti-islanding device: Something that will disconnect the grid if the grid goes down. ... From what I can see, this isn't an easy problem to solve in a generic manner, mostly because of the dead zone (when your incoming power is balanced very closely with your consumption). I haven't been able to find any commercial devices (except for a company in Germany) to do this sort of thing. ... One guy used two series-wired contactors for the job, powering the coil from the mains. The idea is that if the mains drops out, the contactor should disconnect. I'm worried that feeding back enough power might be sufficient to keep the contactors closed, that is: I don't see how the contactor cannot accidentally be powered by feedback power.

*** (Wondering IF this is True ??? ) ::: ... Getting back to your question regarding the contactor, Yes, it would work. For your invertor to keep the contator closed during a power failure, your invertor would need to supply enough power, to power the rest of the grid :) That should be one beefy setup : ... although this solution might work in practice, legally this is not allowed, as the contactor might fail in the closed position, resulting in somebody's death.

*** (an Interesting Related Challenge ) ::: traditionally only the GTIs can be connected to the grid. But Victron has done something really amazing and all quatro and multiplus inverters are supported. You can run it in hub configuration where it can run connected to the grid, exporting power. ... What I really want to do is export just enough to power the rest of the house without any of it actually getting out on the grid. Confusing? Let me explain. Like many people, my inverter feeds only some circuits in the house, leaving the rest to run from the grid only. In other words, there is somewhere I can export electricity to where it can be used by myself (before the inverter, but after the grid connection), before it ends up going out on the grid (which I don't want, because I have a dumb prepaid meter). ... I ideally want a current sensor on the main incoming line, and I want the software in the inverter to balance things so that current on the incoming line hovers just above zero, thereby avoiding export. If I can convince someone at Victron to write an assistant for this use case... I'll be in business, but this sort of thing only happens if enough people want it. >>>


*** (This Looked more like a solution I have not yet fully understood: Need to study more / a 2014 post from South Africa ::::

It's relatively simple ... Put a current sense on your grid side, electronics must monitor amps and if it exceeds rating of your system the grid contactor must drop out. Mean while power continues thru the inverter powered contactor to the house load. ... the fact that the grid is down means that south africa is demanding power from you, excessive load. when you set the trip current it must supply the house and excess to the grid but any more than that it must drop the grid contactor out and protect the inverter and electricians working on the line. Extra electronics can be used to monitor a balance. IE Load is using 10A, inverter is supplying 20A and grid is taking 10A. 3 current sensors. now grid voltage goes down from eskom supply and grid becomes intensive load to your system. amp are up current load becomes excessive, contactor drops out. Now you monitor the grid voltage to see its down on the town side of the contactor. Make the contactor only pull back in when the town side voltage comes back up. It's a combination connect and disconnect for different reasons thru 2 or 3 contactors. ... Just remember when all contactors are out, voltages can be picked up on both sides of the contactors to signal your electronics or power your contactors on when you want them on and off. when all contactors are in it acts as one line, so breaking the line momentarily and sensing voltage as there or not will work. As soon as the voltage is back from Eskom that contactor or relay in back in. Flip flop contactors can also be used and there are more angles that can be wangled out but at more cost and parts. hope this helps.

And there is more to study on that thread if you are interested :+)
 
I recently asked my local high end solar / & long time motorcycle buddy re: questions about Grid Tie, and lineman protection. He said relays have been made work for lineman protection (though I do not yet fully understand/ hoping to get some diagrams ). IN Also wondering about a possible small grid tie system option: that maybe I might later be able to be integrated with my 6000 watt 3x LV242s set up ... (do not yet know if that is somehow possible) ... I got steered toward this:
Panasonic Evervolt avac 105 / & similar/ possibly same under contrasting label/ to compare prices: & ElectriQ

EVAC-105-2 AC Coupled Mini Storage System New

The EverVolt provides power to the essential load by utilizing power from PV panels, the utility and batteries. When the PV panels (two string input) generate enough power, the inverter can support the essential load, charge the batteries and feed back to the grid all at the same time. When the energy generated by the PV panels is not sufficient to support the essential load, the inverter takes power from either the batteries or the utility depending on the mode the homeowner has selected.To accommodate various power situations, the EverVolt is designed to handle continuous power from PV panels, batteries and the utility. When the MPPT input voltage from the PV panels is within the acceptable range, between 250 and 430VDC, the inverter is able to feed the grid and charge the batteries.

... With the AC Coupled EverVolt, energy storage can be added to homes and small commercial buildings, with or without a PV system. The AC Coupled EverVolt can be AC-coupled with existing PV systems, either with string or micro inverters, to allow continuous use during utility outage

I left my contact info with panasonic evervolt / ... to talk tech story and get prices ... Caught my Intersts as I love to be feeding to Grid. Saw You Tube has some info on EverVolt options too :+)
 
Hello Hedges, i think Victron has one:

View attachment 29033
Looking this up to understand it, and get a price cost left me scratching my head about if it would work for anti island, or how it might work; after looking at a data sheet. I download this wiring diagram; still do not understand what I am looking at ??? If anyone has some insights to offer/ my eyes are on this thread :+)
 

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  • Ziehl UFR1001E.jpg
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Price looks like 250 GBP


Schematic has it monitoring grid connection, and controlling an external relay to disconnect PV inverters.

If it performed "active" anti-islanding it would drive pulses/frequencies of current to test grid impedance.

"Passive" would indicate it watches but doesn't drive; I'm not as clear how that could work. Maybe just meaning it isn't a PV inverter? Or maybe it injects dropouts, pulling current from line to neutral, rather than injecting power. That should work.
 
re: questions about Grid Tie, and lineman protection. He said relays have been made work for lineman protection (though I do not yet fully understand/ hoping to get some diagrams ). I
Wondering what more simple relay might possibly make sense to me for anti island protection at lower DIY cost; I will likely remind / ask my solar tech buddy if he has found "any diagrams" he mentioned .. to me earlier. ... and Re that "Panasonic Evervolt avac 105" my solar buddy steered me to check out; I left my contact to hear from their sales/ tech, found no purchase prices/ and think this company sells complete install packages of their equipment, and may not have equipement sales dept only dept. (but not sure :+) ...still researching for options for anti island protection (if that is proper term for cutting grid out from a Solar system to grid/ to cut that asp/ when grid goes down and is no longer supposed to be electrified ... :+)
 
Price looks like 250 GBP


Schematic has it monitoring grid connection, and controlling an external relay to disconnect PV inverters.

If it performed "active" anti-islanding it would drive pulses/frequencies of current to test grid impedance.

"Passive" would indicate it watches but doesn't drive; I'm not as clear how that could work. Maybe just meaning it isn't a PV inverter? Or maybe it injects dropouts, pulling current from line to neutral, rather than injecting power. That should work.
ever seen prices? welcome info on price range, and/or web links showing price of this kind of equipment, ... to know what is out there ... I live in USA ..so now searching for Ziehl UFR1001E $ w that $ symbol :+)

edit later to add this NOTE on my find: on back order w price of about $336
£249.90 excl. VAT = about $336

web searching for "diy design for anti-islanding device" and looking at the images first / as I want to know the less expensve options if there are any ???
 
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Wondering what more simple relay might possibly make sense to me for anti island protection at lower DIY cost; I will likely remind / ask my solar tech buddy if he has found "any diagrams" he mentioned .. to me earlier.

I don't think anything other than a UL listed anti-islanding or zero-feedback system should be used. (or equivalent for non-US markets.)
The requirements have been thought through to a reasonable extent, and the testing process for certifications is reasonably thorough. This is meant to reduce the chance of killing someone to an acceptably low level.

If you want to backfeed the grid, just buy a used inverter with UL1741 certification. They can be found starting around the price of that add-on anti-islanding device.
 
I don't think anything other than a UL listed anti-islanding or zero-feedback system should be used. (or equivalent for non-US markets.)
The requirements have been thought through to a reasonable extent, and the testing process for certifications is reasonably thorough. This is meant to reduce the chance of killing someone to an acceptably low level.

If you want to backfeed the grid, just buy a used inverter with UL1741 certification. They can be found starting around the price of that add-on anti-islanding device.
Been looking hard on Internet, to understand more; ... and kind of coming up with same line of idea. I will next be looking closer at the specs for amp capabilities.
 
Can anyone confirm if the inverters have anti-islanding protection?
Did you ever get an definite answer to that question / from MdDavvv's very first post in this thread : : Does the MPP LV2424 have anti-islanding protection? I doubt it does, but do not know. Was about to email ask MPP to get an answer , and will scan this thread a bit more too :+)
 
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my growatt spf3000tl does not do grid sell back. I guess there is a grain of salt there depending on how much you trust MPP and growatt are the same thing.
 
Did you ever get an definite answer to that question / from MdDavvv's very first post in this thread : : Does the MPP LV2424 have anti-islanding protection? I doubt it does, but do not know. Was about to email ask MPP to get an answer , and will scan this thread a bit more too :+)
Apparently not, but LV6548 does:


LV6548.jpg

But LV2424 doesn't say that.

So with UL1741, LV6548 would be safe to interconnect with and backfeed the grid.

However, you may not be able to get a permit for connection as a new installation (not required as replacement for an earlier grid-tied inverter) if the latest building codes require new features such as California's "Rule 21", which requires the inverter to remain on-line for a while during grid disturbances to help maintain grid stability. (That goal might conflict with your personal goal of disconnecting and providing UPS to your own local loads.)
 
Apparently not, but LV6548 does:


View attachment 29288

But LV2424 doesn't say that.

So with UL1741, LV6548 would be safe to interconnect with and backfeed the grid.

However, you may not be able to get a permit for connection as a new installation (not required as replacement for an earlier grid-tied inverter) if the latest building codes require new features such as California's "Rule 21", which requires the inverter to remain on-line for a while during grid disturbances to help maintain grid stability. (That goal might conflict with your personal goal of disconnecting and providing UPS to your own local loads.)
Great info. Thanks :+) In my view, that still leaves me wondering if the LV2424 might have anti-island ability without MPP jumping the expense hoop of getting it TUV certified. It would likey be hard to get a definite answer anywhere, but I might see what Ean over at USA MPP "says". If I do that, will share the response. ... I actually just asked that question MPP via your web link to LV6548. I will share their response, if I get one, ... later.

Added Note: The LV6548 looks very interesting to me. Currently price at about $2.2K plus $385 shipping for two of them from China/Hong Kong/Taiwan ... (Need wo minimum for 240ac Split phase) . & two cold provide 13 kW (54.16A x 2) of power, and take in input up to 4000 watts of Solar PV panels each, at up to 250vdc IN. I just download the pdf manual to look closer at. I wonder what idle consumption watts it sucks up, and if it could meet grid tie requirements in California USA.
 
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you may not be able to get a permit for connection as a new installation (not required as replacement for an earlier grid-tied inverter) if the latest building codes require new features such as California's "Rule 21", which requires the inverter to remain on-line for a while during grid disturbances to help maintain grid stability.
Re: MPP LV6548 ... and the "Rule 21". I wonder what that rule is about. Is it the utility companies protecting their sort of monopoly interests? or really related to better safety? ... I have always thought it was ridiculous to hear of friends with grid tied solar not having any electricity available from their solar panels when the grid went off. I see some newer hybrids on the market that have an option for battery backup, and some much better independence options. I wonder what DIYs with permitted grid tie set ups are doing to use their solar panels when the grid goes off. I know the challenge would be grid ties usually run much PV at much higher DC voltage, maybe up to 600vdc to their grid tie inverters. If I had such a set up without batteries, I would be figuring out some high current relay options to re-route some of those PV panels to a smaller battery based set up, maybe like the LV2424s.
 
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