Grid tied micro inverters adding a battery

[Carse]

I have looked and can't seem to find a clear answer. Or maybe I'm terrible at asking questions

I have an enphase solar system with iq7 micro inverters.

I also have a 15KWh battery bank that I want to add as a back up and have the battery power the house at night when it isn't producing solar.

My main confusion is how to charge the batteries from solar when the grid is down.

The envoy/iq system shuts down if the grid is down. Can I add a transfer switch and a PLC to tell the solar system to stay up to charge the batteries?
Frequency shifting inverters sound like they could do that but is seems like I would need to connect the inverter output to its input, that sounds like a good way to kill an inverter.


I know enphase has a complete system with the ensemble stuff but it's not available and is also overpriced and I already have a battery

 

[chousley]

yeah, I'm looking for a battery system (other than overpriced enphase) to hook up to my enphase microinverters. Thoughts?

 

[wtfg]

You need a hybrid Inverter, that can AC couple
Outback Skybox or Schneider electric our two that would work!

 

[copec]

For a seamless system you insert the AC Couple battery inverter between the grid and a loads + grid-tie inverter(s) panel. Then generally you program the battery inverter when to direct energy in and out of the batteries and when to just let energy flow through it and sell to the grid.

Googling AC coupled diagram gives good illustrations from the different manufacturers:

ie

 

[Archetype-IS]

Sol-ark could do AC Coupling. Might be able to do batteryless too. Haven't read the new manual.

Magnum PAE series - not as fancy as the newer hybrid but it could do the job.

 

[svetz]

I have an enphase solar system with iq7 micro inverters.
I also have a 15KWh battery bank that I want to add as a back up and have the battery power the house at night when it isn't producing solar.

My main confusion is how to charge the batteries from solar when the grid is down.

I know you don't have Enphase batteries, but if you did they'll automatically recharge from solar or if overcast can be recharged via the System Controller's, previously known as "Enpower", generator port.

If you're not using Enphase batteries, there's no "official" way to use them in combination with IQ7's as "spoofing" them with an off-grid inverter can cause them to backfeed the off-grid inverter doing "bad" things to it (see the thread incrementally adding AC batteries). AC Coupling is the only sure way to do it successfully that I know of.

Unofficially... it should be possible for an off-grid inverter to connect to the generator port. You'd need at least 1 IQ8 to keep the other IQ7's running off grid. For solar charging a controller would have to flip relays to activate the charger and deactivate the pack based on available excess amps.

If you don't mind waiting, they bought up ClipperCreek and are working on an integrated V2H solution, but it's probably a couple of years out.

 

[gwang_hoops]

If you don't want the AC coupled solutions mentioned previously with a separate backup load panel, get the Sol Ark 15K where your 200A main panel is the load. ~$8K.

https://www.sol-ark.com/wp-content/uploads/2022/04/15K_Specs_4_27_22-1.pdf

 

[Carse]

Will an MPP Solar LVX6048WP do the job?

 

[copec]

Will an MPP Solar LVX6048WP do the job?

It can’t AC couple to your existing microinverters, so I would say it’s not what you’re looking for.

 

[ncsolarelectric]

When the grid is down, you charge the batteries from a generator and if you have the Empower Smart switch, and use the Generator Input, then the IQ7 inverters will run in parallel with the generator. So some of the energy charging the battery is coming from the sun and the generator is just idling. However, if you don't have the Enphase Encharge battery, then you probably don't have the Empower switch either.
Given that's the case, then an MPP will work but you'll need more solar panels to connect to it. There's no way to put an A/B switch on the Enphase cables, and if you do you'll probably void the warranty on the inverters.

IMO, when you chose Enphase, you entered a relationship for the life of the system. So, I hate to say it, but you should really consider going with Enphase and operating their equipment as it was intended, or you will never get any support when things go wrong. They have it all figured out, but it needs to be done their way. My battery was delivered just last week. They're available.

 

[davgraham]

With Enphase IQ7 you can't get power out of them when the grid is down, only the IQ8 has grid forming capability. The IQ7 is required to shutdown with grid failure it needs grid to sync to. With the IQ8 and grid forming, you still need the IQ switch controller (~$5k) that disconnects the grid in ul1741, CA Rule 21, way to comply with utility rules. The IQ8 talks to the IQ switch to allow grid forming.

 

[Soltre]

Asking ontop of already proposed question…

Could we put a Y splitter on the PV output cable of the panel BEFORE it goes to the microinverter, and send 1 half to the IQ7/8 and the other half to the house where we could charge a battery?

Would the power from that panel simply show its lower when charging a battery?

Or does that screw it all up somehow or its too much power due to them all being connected together?

I just want to be able to use the darn panels (at least some) during an outage that may last a few days to charge Jackery, battery banks, maybe Ryobi batteries, etc.

Thoughts? Thanks so much!

 

[Shimmy]

Asking ontop of already proposed question…

Could we put a Y splitter on the PV output cable of the panel BEFORE it goes to the microinverter, and send 1 half to the IQ7/8 and the other half to the house where we could charge a battery?

Would the power from that panel simply show its lower when charging a battery?

Or does that screw it all up somehow or its too much power due to them all being connected together?

I just want to be able to use the darn panels (at least some) during an outage that may last a few days to charge Jackery, battery banks, maybe Ryobi batteries, etc.

Thoughts? Thanks so much!

No. Too many problems to list, but in essence you cannot parallel MPPT controllers to a single source.

For @Carse, look at the Show and Tell threads from @GXMnow and @400bird; there are others as well. A grid forming/hybrid inverter will provide the voltage reference for the iQ7's to operate obliviously. The iQ7's provide power, and it goes to the load and excess charges the battery. If production is less than the load then the deficit will come from the battery. When the battery approaches capacity the inverter increases voltage/frequency which shuts down the iQ7's.

 

[ncsolarelectric]

No. Too many problems to list, but in essence you cannot parallel MPPT controllers to a single source.

For @Carse, look at the Show and Tell threads from @GXMnow and @400bird; there are others as well. A grid forming/hybrid inverter will provide the voltage reference for the iQ7's to operate obliviously. The iQ7's provide power, and it goes to the load and excess charges the battery. If production is less than the load then the deficit will come from the battery. When the battery approaches capacity the inverter increases voltage/frequency which shuts down the iQ7's.

It depends on the MPPT controller, but in general, this is true. Putting a lossy power resistor in series with each MPPT will decouple them somewhat as well.
Here's another way, if it's a 48V battery. Get a 48V charge controller and connect the input to your panels and the output to the microinverter and the battery. It could make a nice AC-coupled battery with my Hoymiles inverters. I've been thinking about it already.