Hybrid inverter recommendation w battery, microinverter solar, grid-tie

[lamberStye12]

Hi, I did some searching around the forum and I think I need a hybrid inverter my situation but when I reviewed the spec sheet of a few inverters I still wasn't sure if they supported my situation. I am hoping you could recommend a few inverter models based on my situation. I will probably discuss further with the inverter companies once I have 2-3 options to choose from.

So the subject is fairly clear on my config but to amplify, I have 6kw of existing solar with colocated enphase m250 microinverters terminated at my 100A split-phase AC main panel in several breakers. I will likely increase the solar in the future. I don't have/desire a critical loads sub panel. I will use a 48v lfepo4 backup battery. My goal is for the battery to act as a temporary whole house ups with solar assisting if sunny.

The issue that always trips me up when I decide to invest in this is that the solar is ac and shuts down if the grid goes down. If an inverter restores this ac power temporarily via the battery, the solar will sync with ac and start up again of course. However the inverter must be able to manage the situation where the batteries are fully charged, it's still sunny, and the house isn't drawing any load by shutting down the solar in some way (disconnecting breaker or moving ac signal out of phase).

Anyways, looking forward to your feedback on this one and hoping a few hybrid inverters exist that handle this config specifically.

 

[aido_3927]

I am in the exact same situation as you, apologies as I haven't got an answer but am offering a bump in the hopes someone who has done this can offer some insight!

The closest I have found is that the only inverters that will support this setup are;
SMA Sunny Island
Outback GFX/Radian
Magnum energy

However I haven't got information on how they're actually set up with microinverters at this stage.

 

[Ampster]

The closest I have found is that the only inverters that will support this setup are;
SMA Sunny Island
Outback GFX/Radian
Magnum energy

Assuming you are talking about GT micro inverters tied to a hybrid inverter in a grid interactive situation there are lots of new offerings.
The Outback Skybox is designed for that and the former off grid Radian is now capable of AC coupling to micros. I am not certain about the older GFX models and they are 120 volt so you would need two of them and/or and autotransformer and an automatic transfer switch which is included in the Skybox. Outback has also just announce a new larger hybrid called the Mohawk.
Sol Ark has also announced a larger All In One hybrid that is larger than its two other hybrids.
Some people have also used Schneider equipment. I do not know much about the capabilities of Sunny Island or Magnum. There are also many Chinese offerings some of which also have UL ratings.

However I haven't got information on how they're actually set up with microinverters at this stage.

The concept is AC coupling and the setup may depend on your use case. Is my assumption correct that you have a grid connection? If so tell use more about your goals and use case?

 

[SparkyJJO]

This is what I am trying to do too (Chilicon CP-720 grid tied microinverters). Seems you have to have an inverter that has the same capacity as your solar output, from what I understand so far. At 6kw you're ok with one Outback GS8048A, for example. But if you go larger you need more. It gets expensive fast. I have about 8kw of solar so I have to double up (big ouch$) or use only half, or maybe use other equipment. Not sure. Considering Victron Quattros, but I really don't know, and I'm leery of dumping big $ on one giant experiment.

 

[Ampster]

Seems you have to have an inverter that has the same capacity as your solar output, from what I understand so far. At 6kw you're ok with one Outback GS8048A, for example. But if you go larger you need more.

It is a complicated process to AC couple but the advantages of a cost effective integration are worth the effort. There are no hard and fast rules and it also depends on the amount of batteries in that system as well as the throughput capacity and not just the inverter capacity of the hybrid inverter. I do not know the details of the Radian but I know that this is an emerging field and Outback and others are coming out with products with larger capacity for AC coupling.

I will use my Outback Skybox as an example. It has a 5kW inverter but I have 7kW of micros AC coupled to it. Apparently the Skybox can handle up to 8kW of AC coupled inverters. Even then there are work arounds if one has more GT inverter capacity than the hybrid inverter can handle. . One of those which I considered when I was putting my system together was to only AC couple half my micros to the Skybox if capacity was an issue. That way, 99 percent of the time that I was on the grid all my micros would be producing. When the grid was down I would only have half the micros producing. Fortunately I was able to have all 7kW of my micros AC coupled. I do have 42kWhs of batteries and they act as a buffer to help my Skybox vary the output of the micros as my loads change when the grid it down. As I mentioned, it is not an issue when the grid is up because the grid presents an infinite load to the micros and my Skybox so the grid is the buffer when loads change.

 

[SparkyJJO]

YeahcI thought about that, just using half of my solar while grid is down (I have two lines feeding down from the roof so easy to split them up), and could piggyback another Radian later if the load was worth it.

Interesting note though on the skybox, I had no idea it supported more. I'll look into it.

 

[aido_3927]

The concept is AC coupling and the setup may depend on your use case. Is my assumption correct that you have a grid connection? If so tell use more about your goals and use case?

Ok yeah sorry, didn't want to hijack someone else's thread but hopefully my case will help others!

I've got a 10kw PV system with Enphase Microinverters monitored through an Enphase Envoy IQ. It's grid tied and I currently export excess solar that isn't always being used. I don't think there's really anything else in my system, in the control box there's the Envoy IQ unit then a couple of breakers and 2 relays so that's all I'm aware of having to contend with.

I want to construct/install a LiFePO4 battery to make better use of the solar and reduce my electricity bill and was looking in the area of around 20kwh which can be any configuration required (48v, 120v, etc).

I'd be happy if I could continue to export solar with a battery backup system but if I lose that functionality then that's fine, I'll still make better use of the solar with a battery backup and no export than I would otherwise.

The misso however does want to have no real restrictions on power use when on the battery, so if she wants to use her two ovens that are rated at 3000w each whilst the reverse cycle airconditioner is on (even though she almost never uses two ovens together), she wants to be able to do that, meaning big inverter (or more than one?). If that's not feasible though, then she might have to make do as I am not familiar with cost let alone availability of anything that may work for my case.

Should also mention I'm in Aus, not sure if availability for all brands would be as good here just in case that might influence anything.

 

[BarracudaBob]

Thought exponent, don't try this at home until they do and tell you it worked...

Can you have a small PV setup with microinverters connected to a EG4 3K output? Say you have a shed way in the back yard that is fed 120Vac from an Hybrid Inverter on the other side of the property. "What if" you had a few panels on the shed and connected it to the non-grid inverter output?

 

[DIYrich]

That is load connected AC PV. If you have excess production when grid is down, that is very bad. No where for the power to go.

 

[timselectric]

Magic smoke is pretty, this time of year.