Enphase IQ8 vs IQ7

Hi, I’m thinking of holding out till IQ8 is released to the market in going from my present single phase 6 KW grid tied basic system to a hybrid, off grid capable system. I am a sparky.
I’m on 3 phase which presents some issue’s. I don’t have any 3 phase appliances.

Currently I have a back up permanently mounted 11KVA single phase diesel geny, so when I lose power, I can manually turn the changeover switch which shorts out all three phases on the load side and start the geny.

My question regarding IQ8 is and feel free to pull it apart and maybe no one knows the answer yet, I’d like to put more panels in across all three phases in the future, maybe 9KW in total, and change over from my Solax single phase 5KW grid tied inverter to Enphase micro inverters IQ8.
It appears the microinverters can detect the frequency/phase and sync as needed but what if in a hybrid system where I’d like to run it all as single phase when the grid is down, can the microinverters sense that it is all on one phase now when a change over switch shorts out all three phases and adjust accordingly to the new reference frequency? ie: the battery bank is generating single phase only, charged up by the single phase geny when needed.

Single phase is simpler/cheaper for components and ensuring the most is made from power generated as well as the Cat/Gough Geny is single phase.

Any thoughts

Cheers
Martin

Hi @Den_Thomson

Have you got any thoughts on hanging out for the Enphase IQ8 range for these reasons? It’s an interesting one.

Cheers
Marty

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Hi, at this stage I will hang out for the IQ8. The grid tied inverter I installed this year is only a cheap way to get up and running until I figure out the next stage. I do like IQ8s concept and would like to AC couple all components in the future. Steep learning curve for me but very enjoyable. Playing around with batteries at present as I can get used banks from substations. Cheers Martin

Hi Guys,
Sorry, it’s taken me so long to respond I’ve been flat out, which is weird considering it’s been raining cats and dogs over here lately. I wanted to run this by a few guys that are more solar savvy than me before I responded, I’m a Fitter Machinist by trade, that in itself should tell you I’ve worked on some pretty huge voltage gear. But I’m no sparky. Anyway, it sounds to me like (Vandevere) Martin is waiting for IQ8 in as far as it’s going to be grid agnostic and should do the trick. IQ7 is smart enough to detect and adjust to frequency changes. I spoke to Enphase today (regarding another Envoy R comms issue, seems to be the only issue with any of Enphase systems we have installed and only the old Envoy R’s) I mentioned this topic with the guy, and he said cabling may be an issue as the 3phase cabling works by sending down phase1 then phase2 then phase3. In his explanation of it, he thought that throwing the change over switch may limit the inverters into giving you 1/3 productivity. I will keep hunting the answer this as it is a little out of the square😉, I quite often chat with off-grid electrical engineer guys, and I think the answer lies there.

Questions.

  1. No 3phase appliances, but what do you have running on each phase?

  2. Is installing single-phase Enphase IQ8 an option as you seem to have a
    single-phase solar inverter now?

  3. Would a conversion back to single phase break the bank?

Bad News,
It turns out that IQ8 will be launched 1st quarter USA only, Australia middle of the year (if all goes well), this pisses me off no end because the good panels are getting out of range size-wise.

Kind regards
Den

Hi Den
Thanks for your reply and for asking around.
It’s not unusual for me to come up with out of square questions :slight_smile:
I’m on a lifestyle block so appliances used include a 2HP single phase pump which is used for irrigation as well, two electric water heaters (large house) on nightrate, Logburner heats the house but have a Air Con as back up and cooling in summer.
At present I have all load on one phase to maximise solar as buy back rate is around 8c in NZ. I would like to use all 3PH so I can put more panels in, 5KW limit per phase in NZ.
Sort of like having the best of both worlds is what I’m after, spread load over 3PH as the voltage does dip a bit much on one phase, install up to 15KW but then when the grid is down I can use the simpler single phase set up from a battery bank and back up diesel geny when the changeover switch is used to short the 3PH.
Thanks for checking with the off grid experts.
Looking forward to getting a plan together but ultimately will have to wait anyway for the IQ8 to arrive.
Cheers
Martin

I have a system of iQ7 inverters now, and hope to add an EnPower switch and EnCharge battery when they become available, so I have been researching this gear for a while now. The Enphase Ensemble will not work in a 3 phase system, at least not when it is released.

What are your single phase and 3 phase voltages there? Here we have 120-0-120 (240) sinlge phase, and our 3 phase is 120-120-120 from neutral and 208v across legs. In Europe, I dealt with 220-220-220 and 384 across legs. In a non ensemble system, the microinverters operate at 190-250 volts, so in a 120/208 3 phase system, they would be wired across 2 phases, a-b, b-c, or c-a respectively. In a single phase setup like I have here in the USA, they are all connected from line to line at 240 volt. Most of my loads are single leg 120 volt and it depends on the line transformer to equalize the load if there is more current on one leg than the other. If you are at 220/384 3 phase, your setup should work.

But if you have a 120/208 3 phase setup, jumping the 3 phases together would literally be shorting the output of all of the inverters. You could drop to using 2 legs in a single phase arrangement, but this is where you end up just using that 1/3 of the microinverters. The rest of them are going to the now dead leg.

Another possibility would be using a much more complex transfer switch. Add a single phase panel that feeds your important loads that need to be backed up. When the 3 phase power is available, 2 legs can feed that panel. And when there is a power failure, the generator can feed it as well.

The new iQ8 inverters will be able to supply power during an outage also, so you could then use the switch arrangement to move the solar panels and microinverters to the backup single phase panel. They big benefit to the iQ8 is that they will be able to lower their current output to match the load you are using, so the power island voltage will not go to high when the load is reduced. My iQ7’s are not fast enough to do that, so I need to have at least one iQ8 for every iQ7 for this to be able to work.

By late December, we will have a lot more info available about the Enphase iQ8 and the new EnCharge batteries.

My current system has 16 iQ7’s. If I add 2 EnCharge 3 batteries (they each contain 4 iQ8 inverters), then I just need to swap out 4 more of my iQ7’s for iQ8’s and I will have 12 iQ7’s and 12 iQ8’s.

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Hi from NZ
Our system in NZ is 240/415 3 phase so hopefully this will work.

Thanks for your idea on a essential service single phase panel and I will keep that in mind.
Looking forward to more info on the Enphase iQ8 from Dec onwards.

My system is running sweet for now. I’ve had to lower the tap on the 11KV transformer supplying our property (I work for the local power company) so the inverter doesn’t start clipping its output on high voltage.

Looking forward to putting more panels in on the other two phases when the time is right, we are only allowed 5 KW per phase.

Playing around in the meantime with an old bank of batteries from a substation, 12 x 12volt 100amp/hour deep cycle, via a separate inverter/charger to give a reliable constant supply for minor equipment during an ongoing outage.

Thanks, Martin