Using Grid Tie Inverters Off The Grid (Part 2 of 2)

Remember to join the Discord Server! / discord
In this video, I continue where I left off in a previous video I made (Tricking an grid tie inverter with an off grid inverter), testing a theory I had. Turns out that it does work. I could have done a bit better in this video and shown with a clamp meter that there was indeed current running through the lines, but you will have to take my word for it that it works.
If you are going to do this on your own or at your own off grid system, do so at your own risk. Keep in mind that with this setup, the batteries will not stop charging when they are over voltage. It is only a good idea if your background loads are greater than your grid tie solar input, or if you have a diversion load. In my case we have a hot tub with a heating element that turns on to absorb extra power, to make sure the batteries don't end up overcharged.
This works because the off grid inverter has an H bridge setup. The inverter pulls from opposite corners of the H, essentially switching from positive to negative, 60 times per second (It actually does this in steps, to get close to the sine wave). You essentially have 60HZ but a modulated square wave, at 48 volts (battery voltage). In my case it is then run through a step up transformer within the inverter to achieve the 120/240v split phase. This is then filtered and output of the inverter.
In my setup, the output of the inverter then goes into a load center, and is distributed to the various different loads. In my case one of the feeds out of the main load center is "Panel L2", which is the panel in our garage/shop shipping container. This is then fed through a 30 amp 2 pole breaker and runs to the microinverters. These microinverters look at the voltage on the lines connected to them, and lock on to the same signal. They then push power back through the same wires they collected the source signal from. This means any loads in panel L2 and the main load panel are being powered in part by the micro inverters.
Any extra power or a higher net than what the load are using then goes back through the H bridge inside of the inverter. This works because the grid tie inverters are still sync'd to the line frequency, so the transistors or MOSFETS inside of the inverter are opening at the same frequency as the microinverters are locked to....This means the micro inverters can push back through the MOSFETS inside of the inverter, and the current is essentially rectified back to DC and fed into the DC Bus. If there is sufficient voltage, it will charge the batteries, but like I said before and I will caution again, it cannot tell when to stop charging because none of the electronics in the system actually know that this charging is happening. Obviously if the voltage did get high enough, the solar charge controllers would see that the battery voltage went up and they would taper back on how much current they are putting out, but still has the chance for fault.
I can't say enough, if you are going to attempt something like this, do it AT YOUR OWN RISK.
Stay tuned for more videos, and as always, thank you for watching and making this channel sucessful enough to keep building cool stuff and putting it on the internet!!!

[@chadnye8737]

Love the setup, nice to be off grid. Keep it Green

[@pey-yote]

That may look like an A.R. pistol, but it’s actually a very sophisticated energy compression encabulator

[@mikepowell4189]

Haha awesome

[@ev-olution8597]

Using Modbus compatible grid tied inverters with export limit function in connection with Modbus smartmeter connected just after your offgrid inverter will prevent energy to be back fed to the batteries.

"This is just going to be temporary", a phrase right up there with "five minute job".

[@Lawiah0]

The check is in the mail.

[@egn83b]

I wonder if slow trickle charging at 200ma would bring one of those batteries capacity back up for a week. The other thing that helps bust sulfation is a capacitive charger which is a bridge recifier capacitor and diode at 120v which could help but if they are done its time to upgrade.

[@coreyellisart6877]

Hello and good afternoon quick question for you you stated you are generating your own pure sine wave to trick the grid tie inverter I was thinking about feeding my grid tie inverter with my off-grid pure sine wave inverter basically putting both output loads on the same panel which essentially should trick the grid tie inverter to staying on. This is solely because my electrical company does not want to give me a net meter can I already have grid-tie inverter setup. I heard a lot of people claiming that the grid tie inverter are designed to put out as much power as they can but the reality is if supply and demand based on Ohm's law even if there is 5000 W available on the grid tie inverter to put out and the power is not being used on any load it essentially will just sit there and idle correct me if I'm wrong.

[@artsmith103]

I don't understand enough to give complete answer but it's possible without Net Metet you'll be charged for the kWh you backfeed to the grid. Study the load/generation limiters of new IQ8 and I think you'll learn more about what you're missing.

[@frankz1125]

Why would it over charge? Does the inverter not have a voltage cut off? Cool vid

[@HighTechLab]

Inverters high voltage cutout is 64 volts, far above what the safe charging voltages for FLA are

[@frankz1125]

@@HighTechLab o. I thought it would be more like 58. Ya thats a bit high.18s LiFePo4 or 16s lipo😁

[@dumptrump3788]

The Grid Tied Inverter shouldn't work any differently when hooked up to the utility power line or a non grid tied inverter. A 120v 60hz sine wave is a 120v 60hz sine wave & the Grid Tied Inverter will sync to it. High ripple will kill cheap electrolytic caps, so maybe one inverter or the other is not exactly sinusoidal or has high frequency noise or harmonics. A better solution might be to feed your solar panels into the batteries & let the non tied inverter handle it all.

[@franka12404]

are you using PVC for your airline? I think that's dangerous right?

[@HighTechLab]

I can't say its the best idea. This container that we use as our "shop" is supposed to be temporary enough until we get the 4,000 sqft steel building (That we already have but is just sitting flat on the ground) set up, and at that point we will either do copper for aluminum air lines. Especially the 90 through the wall down to the drop of the air compressor where it can be exposed to sunlight. Thankfully that part is painted to block some of the UV rays.

[@climatechangepreppersfaceb2148]

You really need to solve the overcharging before the lithium goes in

[@fourzerofour7860]

Yea, I am worried there too. XD Hoping he puts in a good BMS at least so there will just be a power outage, and not an intense fire in that room.

[@climatechangepreppersfaceb2148]

@@fourzerofour7860 Lifepo4 don't catch fire, but they will swell

[@zogworth]

The high pitggots AC driver circuit for an TriStar would would really well for this application. I just use a standard dump load

[@Lawiah0]

@@zogworth I dump-load to the water heater; just like Nuclear Power Plants (boil water).

[@Takaraz83]

Why the gun😂😂😂. Worried about power theft?

[@HighTechLab]

Airsoft

[@N-hunter]

Hi

[@thomasbumgardner6825]

Incredibly intelligent to have a weapon, that's likely loaded, on top of a load center..

[@HighTechLab]

The air soft gun?

[@MicroHistory101]

From what Ive heard, you can do this as long as you are drawing power away from the grid tie inverter or as you said, charging the batteries. If the power line becomes saturated the grid tie will keep pushing power in and quickly ramp up runaway AC voltage until everything burns.

[@pauld7806]

For those that don't know, this arrangement is called AC coupling. The micro-inverters feed power to the output of the off-grid battery inverter. If the sun is shining, and there are no loads on, the power from the micro-inverters will go through the battery inverter and result in an un-regulated charge on the battery bank. The battery inverter typically cannot control this charge current, and If left un-checked, it will cook you battery bank. Some battery inverters are built/programmed to detect this situation and increase their output frequency of the battery voltage gets too high, which causes the micro-inverters to disconnect. It's clunky but it can work. If your battery inverter doesn't have this feature, you really should install some kind of relay to disconnect the micro-inverters if the battery voltage gets too high. some inverters have an internal relay you can use (battery fan setting for instance) or you can get a voltage sense relay to do the job. I wouldn't just leave it like that though. You are asking for trouble.

[@zogworth]

If you can set the voltage disconnect on the grid tie that works too. As the batteries charge and there is no load on the system the voltage generally rises. As it gets higher it will eventually raise above the point where the GTI is no longer a happy bunny and it will shut off. This is only a good idea if you already have dump loads and are just using the voltage cut off to manage your inputs.

[@DavidHalko]

Some inverters, like the GenetrySolar inverter, will shut off the grid tie inverters through a frequency shift, so load shedding is not necessary, once the batteries are completely charged. Nice to see this video! I was getting ready to start projecting videos on a similar concept

[@erictheawesomest]

I did it with my little set up and it will for sure overcharged your batteries. But when I got my ct sensor working it was able to regulate and not push into the inverter.

[@taylorlightfoot]

Hi. The Enphase microinverters are supposed to be 16 M250’s per trunk cable maximum. So that’s roughly 16A. So they’re supposed to be on 20A breakers. I see you have it on a 30A breaker. You probably did that because the trunk line is 10 gauge wire. But that upsize is used to keep voltage drop in check only. Breakers should be 20A.

[@HighTechLab]

Also pulled #10 through the conduit. Good catch.

[@taylorlightfoot]

HighTechLab have you looked into Enphase’s yet to be released iq8 microinverters? Supposed to have microgrid/offgrid functionality, can directly power loads when sun is shining without batteries and can regulate output to meet the load in real time. They’re also supposed to be coming out with new versions of batteries.

[@Electronzap]

Looks good, especially with an AR15 :)

[@TexasVeteranPatriot]

Just came across this microinverter tech today. So you don't necessarily have this AC coupled and freq controlled? Was looking at some docs that said not all controllers/inverters can do freq sync/control and can or will overcharge the batteries when used with microinverters. Looking to use this in a proper off-grid app without having to convert solar DC-AC, except as battery power is required for the load. Easier to use direct source AC to the load than deal with conversion loss with an inverter during daylight hours. Charger loss won't be as big a deal. Can you recommend a design consultant as all the schmucks I've talked to only want to sell a package and not deal with design or non-grid-tied (pure off-grid) systems to suit needs. I need someone familiar with the newer tech. I can speak the lingo, I'm just 10-20 years behind. That and I do 48v DC backup plants and power generation for Ma Bell. I did find a tech brief on AC coupling, but talking to a human sometimes helps the understanding.

[@FreemanCraftMD]

has anyone tried to use a battery and 2 pure singe investors to trick an on-grid investor to think it is on the grid and continue to produce as if it is connected to the grid, I have a farm setup trying to power a 240v well during day time only.

[@JaujauJaujau]

very nice project. how do i find out if a off grid inverter is suitable for charging a battery with energy coming in via the ac out? its the rated inverter power the maximum charging power? last question: how does it change the situaton if the the grid tie can reduce its power via a smartmeter between both inverter via setting and export zero mode? thanks a lot!

[@boringsoftware2093]

great video thanks! so u hooked up the grid-tie-micro-inverters to the AC out of the off-grid-inverters?

[@mga1858]

Enphase go off-grid naturally. Our team installed them, but only for a certain number of panels to qualify. Try doing this with SolarEDGE Inverters. I believe it's possible but haven't found any videos on it yet and when I do I'll update/delete this message in accordance. Thanks for posting!

[@DiyintheGhetto]

I thought using a grid tie inverter it needs to generate a 69 hertz signal from the grid to make it work?

[@Jmunoz1675]

GREAT STUFF. Can this be done with the Enphase IQ8+?

[@awesomedee5421]

This is great. I was just thinking about this but needed to think about it a little more before donating my equipment to the magic smoke. So it does charge the off-grid inverter batteries if the solar panel is generating more power, but eventually, the batteries go boom. I'd love to see what you think of solving that problem.

[@spicethewolf8694]

My two cents would be to simply take your input from the panels and put it through a breaker controlled by your Automation panel. you already have everything you need and your battery voltage(already being watched by the panel if memory serves) controls the breaker and simply set it to disconnect beyond like 95% SOC OR if the sun is down and that will do all you need it to. Even better would be to integrate a load monitor somehow to prevent the positive backfeed anyway but if your right about the h bridge that may be "safe" to do. Good luck either way and I hope you find a safe simple solution ^,.,^. This allows you to turn them on and off on demand like any normal inverter too

[@fabiuh991]

Had to slap my self in the face after seeing the Portuguese flag. Thought I was seeing things

[@creepybag]

i saw a portugueses flag?

[@Sanwizard1]

My MPP inverter shuts off charging when the SOC hits 90%. Is your inverter that dumb that it cannot check SOC and turn off the MPPT charger?

[@HighTechLab]

We have since upgraded our system to 3 of the Sol-Ark 12K units, with a different battery bank.

[@oneGOD58]

Clear as mud. Next please.

[@MartyRothbard]

Find some aluminum to screw the inverters to as a heat sink.

[@mraperish]

"but you will have to take my word for it that it works." haha what?

[@andydaddy2009]

holy makeral andy ... skimpin not....

[@sharonliusa]

Can an off-grid inverter automatically shutoff the input from the solar panels when the off-grid battery is full & when there's no AC loads ? This way the off-grid battery won't be overcharged and explode. Would like to hear your take on this. Thanks so much.

[@Tassie-Devil]

I do understand the theory that you seem to have put into practice. My question is whether this be universally practical for "any" PV-Grid inverter? I am 100% off-grid and have been running a very top-end battery inverter successfully for 10 years now. I have recently been gifted a Grid Inverter designed ONLY to feed PV energy into the grid for the original owners. I'd love to put the re-homed grid inverter into service to utilise excess PV energy for daytime drain, but I am VERY scared that if my battery inverter suddenly sees something trying to push 240V up its rear end, it'll blow all its MOSFETS and stop working. Any wisdom to give me about this?

[@andrewf.7813]

Great video! Just what I was looking for. I have a 220v fronius grid tied solar inverter + panels. I also have a Samlex 12v to 220v battery inverter. Could I disconnect the Fronius from the grid and connect it to the output of the Samlex battery inverter to get the Fronius going? And then at the same time hookup a 12v fast charger to my 12v battery to keep the output of the Samlex feeding the input of the Fronius?

[@camolas71]

A flag from my country in this video 🙋 Who is Portuguese?

[@HighTechLab]

Our plumber. Here's a great guy.

[@CraigDohner]

Whoa, this is nice!!! I luv it Lots of storage too. You get that all tidied up, And you're golden.

[@bryanliggett3257]

I'm wondering i'm wondering why Scott inverter off grid 3500 W and what would I do with the excess power that thesunny boy inverter producers because this opens up a new door for how many solar panels I could use and provides me with much more power currently using outback charge controller

[@zemadeiran]

Thanks for the update, much appreciated Left a comment on your 10000 sub about some lifepo4 cells available on ebay, hope you saw that Keep up the power madness

[@Emtarnold67]

Apologies for commenting on an older video. Towards the end you mentioned overcharging the batteries. Would this be possible with the inverter only making 12 volts? I have a 12 volt panel for maintains my boat battery and there is no charge controller because it only makes 12 volts and can not overcharge the battery. Thanks for the great video you really have me thinking

[@awesomedee5421]

another person who tried this setup had the off-grid inverter ramp up voltage, and the grid-tied inverter blew. so there must be more. One person said it needs to be a hybrid grid-tie inverter. Thoughts? Can you provide the models of both inverters used to investigate this further?

[@brothertyler]

Thanks for this AND especially the explanation in the description. I am doing this now, with a 6KW main inverter and a 6KW grid-tie

[@motostyle6908]

Hello Heres my Querry Can we do the same trick for a 5 kva system and how long it can work . Thank you . plz do reply if there is any answer fr da querry or nt.

[@benkanobe7500]

Where is Part 1?

[@offgridwanabe]

Not all inverters will allow the back flow of electricity Ac coupling is the easiest way to go if you don't want or have a solar charger. One could always hook them up to 2 digital relays and use the aux control to turn them off or on.

[@sparkyprojects]

Don't know about 120v into a battery, but i can tell you what happens if you use a starting charger (i think over 36V DC) on a brand new 12V battery, it blows the top off, and showers some acid about. :P (i was checking a starter charger that had a problem, after i fixed it i want to test it, the engineers gave me a battery, i asked them what a button was for, just as i pressed it, they ducked and ran) :D

[@HighTechLab]

It will be interesting to see what happens. Would be cool to build a "mini thumper" and dump 450v into a battery. Set it up in the middle of the field and RUN

[@leexgx]

Are you sure it back feeds to the battery's as these have a dc to dc inverter inside them that are controlled unlikely the controller will reverse charge unless the inverter was set to do it (them type of inverters have an AC out and AC in i thought it only take power from the in side) more then likely get a high voltage AC warning if the outside micro inverters pushed the voltage to high on the main inverter

[@HighDesertOffgrid]

Would you be able to provide any insight into tying an inverter/generator directly into an offgrid inverter to boost power? The Yamaha I have is capable of piggybacking with a second generator so I am guessing it uses a similar process to sync the output frequencies.

[@HighTechLab]

I've paralleled a Honda inverter generator with my off-grid inverter, but they didn't share the load very nicely. The generator didn't push power backward through the inverter either to charge the batteries.

[@HighDesertOffgrid]

@@HighTechLab thanks for the response. As I mentioned I just need to supplement my panels/inverter to run the AC. I prefer the system to bear the brunt of the load and the genset(s) to add what's needed.

[@pyrojason]

Cool theory test. Did you make the experimental battery destruction video?

[@dama054]

Hi a quick question for you, do you know if you back feed the mpp solar inverters with a grid tie inverter will it charge the batteries like your large inverter via the H bridge as the mpp inverters are transformer less type

[@d.e.cservices4224]

I would like to know how to do that myself can you help with me with that

[@ddwayn2469]

Here in the 3rd world we don't have a stable grid. So during the daytime when it's sunny🌞 the grid-tied system loses power and we are no power at all. I was thinking to connect an off grid inverter and use its 220v output to grid tied inverter input. Will it work???

[@dilevehshee]

it should work but you should cut the grid off through a breaker as not to send any electricity to the grid.

[@thesecret2]

how do you run a grid tie inverter into a power inverter,...is that possible,...

[@HighTechLab]

In some applications it is. In part 1 of this video I go over the logic in my system that allows this to happen.

[@honeybadger6127]

great share.. I've always wondered how a grid tie inverter would work in parallel with an off grid inverter. Thanks for sharing.

[@MStrickkk]

You should consider moving those before filming next time. Doesn't matter that they are airsoft. KZbin is run by sissies and their algorithms will see "weapons of war" and throw you to the bottom of the list.

Your insane delusions are your own problem.

[@MStrickkk]

@ Those are not my delusions. That's just how quacks look at it. They call them big scary death machines because they are scared of things they know nothing about. Don't harrass me for trying to help a level headed intelligent KZbinr.

[@bryanjk]

@@MStrickkk you are correct, as a KZbin addict I see it all the time.

[@HighTechLab]

When I saw it in video editing I considered almost not uploading this video

@@MStrickkk No you're a twat who thinks the NRA is a religion.

[@sylvanenergy]

Would love to have a chat with you.

[@dualmode1]

you would pop your fuses 😁😁

[@fourzerofour7860]

Interesting. Some inverters support the "backfeed" charging officially like that. But I take it yours doesn't officially? I think MagnaSine makes some inverters that support being used like those officially with micro inverters, and they actually can communicate with them to tell them to "back off" when the batteries are full. AC coupling is definitely a nice way to go if you have an existing grid-tie system, or a patchwork of different sizes and ratings of panels. I'd be interested in seeing what happens with your setup when the batteries get toward full. :/ I wonder if the inverter will shut down from over-voltage?

[@Vikingza]

Hi, do you have any wind turbines to help generate power?

[@HighTechLab]

I would love to, but I do not. We get a pretty strong wind across the top of the hill in winter time, and it seems that it blows typically on cloudy days and at night when solar isn't making much power. The hard part is you have to get the county to permit it, and that's not very easy to do.

[@jamest.5001]

@@HighTechLab the county has to permit wind turbines there ? You are not exactly in the middle of town, I think that is a bit over reaching of the government, I'd put up a 1kw turbine and tell them to suck it! I live in a bowl tree wise, and off grid, I think I will try a 5-600 watt turbine, just to see if I can get it high enough to make power! I'm thinking 50' should make it. But about 80' should get all the wind it is possible, unless it's in the 200' range, then it would be about as high as anything in the county, I'm on a bit of hill with a valley going through it, I'm on one side surrounded by trees, so my panels only get sun about 6 hrs a day, so a turbine would help, even if it's 1/2 a kw... I only have 1/8 the capacity you have, with a 24v 5kw inverter, and 1000 ah battery, but my lighting is 12v with its own battery, 120ah lithium, I hope to more than double everything! Add 2500w in solar,