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Am I on the right path... Hybrid inverter questions

waspie

New Member
Joined
Jan 3, 2025
Messages
8
Location
south carolina
New here, not necessarily new to solar. I previously lived in Ohio and permitting in my city/county were far more homeowner friendly than in South Carolina where I live now.

I installed a 8kw roof mounted system as the homeowner, got all the permits myself, and passed all the inspections. Submitted everything to the power company and got onto net metering.

Can't really do that here. Im kind of in an unincorporated area serviced by duke who does net metering but the city my mailing address is in requires you to be a licensed electrician to do any of that. As most of you know, this is a DIY forum and paying 4, 5? times what it costs to do yourself to have someone else do it isn't quite the spirit of this.... right?

So... what if i just forgo net metering (and in a lot of cases its starting to go away anyway...) and go hybrid with no export?

I've been eyeing EG4 12kxp and 18kxp hybrid inverters. From what I understand they look to do what I'm thinking. Initially, due to cost I'm looking to grab the inverter and panels and set all that up. As money permits I'll be adding battery capacity.

Am I understanding it correctly that the 12/18k hybrid inverters will (with CT clamps on the mains) produce only what is needed in the house and send the rest to battery (once I have battery)? And the grid can be fed in via breaker (as is typical in grid-tie setups) and will supplement power produced by solar as needed?

The goal may eventually be to have enough battery to possibly give up having utility power but that's down the road. The grid tie would remain for a while why the entire system is built out. Over time I'd suspect I'd need a second inverter to be fully off grid - it's a big house with 2 heat pumps both with emergency resistive heating (10kw and 7kw + 3 and 3.5 ton condensing units).

I've looked at sol-ark too, looks great but seems to be double the price of the eg4 stuff.
 
I DIYd my small stuff, the solar generator and inverter, but the bigger 2 radian 16 kW total I had a contractor do it. Did not have two years to spend building it.

what if i just forgo net metering (and in a lot of cases its starting to go away anyway...) and go hybrid with no export?
EG4 is very popular and should be posts about specific equipment.

If this is your plan, just make sure this won’t sell back inadvertently. I have an Outback radian and in the grid zero mode, it will at times send power back that a smart ,enter could pick up. I have an interconnect agreement, so it would not matter.

This sell back occurs when a large load like a 48 amp EV charger is shut off.
Over time I'd suspect I'd need a second inverter to be fully off grid - it's a big house with 2 heat pumps both with emergency resistive heating (10kw and 7kw + 3 and 3.5 ton condensing units).
Need a good Energy Adit for these to go off grid. That is a tall order. Two Heat pumps on a five cloudy day cold spree, that would be difficult. I’m guessing you could not get enough batteries.

Could you use a generator for that?
 
I DIYd my small stuff, the solar generator and inverter, but the bigger 2 radian 16 kW total I had a contractor do it. Did not have two years to spend building it.


EG4 is very popular and should be posts about specific equipment.

If this is your plan, just make sure this won’t sell back inadvertently. I have an Outback radian and in the grid zero mode, it will at times send power back that a smart ,enter could pick up. I have an interconnect agreement, so it would not matter.

This sell back occurs when a large load like a 48 amp EV charger is shut off.

Need a good Energy Adit for these to go off grid. That is a tall order. Two Heat pumps on a five cloudy day cold spree, that would be difficult. I’m guessing you could not get enough batteries.

Could you use a generator for that?
possibly but the reality is the grid heaters don't come on much. I have control (via z-wave thermostats) over what it takes to engage the emergency heat and though I've only been here 2 winters now the stretch of time where they're actually needed is fairly short (2 weeks, overnight, max). During the coldest stretch the days are warm enough that the heat pumps are enough and the skies are still clear and sunny.

But that's also why I'm staying grid-tied - for now. Do utilities have a habit of getting after you for sending small amounts of power back? I'm sure the meter is capable, it's the same type/brand/make/model as the one I had in Ohio that was used in net-metering.

I may over time eventually get it passed and permitted as I make friends and find an electrician that would sign off on it but I'm not about to pay 40k for a system I can do myself for 6-7k - it's insane.
 
With two years data and an 8 kW build before that, you’ve got some good data to build a system.
But that's also why I'm staying grid-tied - for now. Do utilities have a habit of getting after you for sending small amounts of power back? I'm sure the meter is capable, it's the same type/brand/make/model as the one I had in Ohio that was used in net-metering.
It’s rare, but it happens. EG4 equipment is pretty popular now. Should search posts for that. A couple people have solved this by removing the loads from the grid running them only on EG4 and batteries and if extra power is needed, charging the batteries with the EG4 Chargeverter off the grid. That will be the only guaranteed way not to back feed.
 
I may over time eventually get it passed and permitted as I make friends and find an electrician that would sign off on it but I'm not about to pay 40k for a system I can do myself for 6-7k - it's insane.
You might want to re-consider your cost of the equipment for DIY. Yes I agree DIY is a lot cheaper than having someone install it. I have no choice but a ground mount (Geodesic dome in the woods) so it's about 300' from my field to the house. But 3 years ago I got a quote from an area installer. They wanted $36,000 for a grid tied (no batteries either) 4kW system. Looking to install 16.6 kW hybrid system this spring Just the Inverter is almost $6,000 then I have panels, the ground mount, wiring & conduit. Before I event get to price in the batteries I am north of $20,000 just for the hardware... Yes roof mounting if that's an option would save some but your still going to be well above $13-15k for the size of a system that would do what you are describing.
Just my $0.02 It's best to have everything planned out and have accurate prices before hand rather than getting 1/2 way into the project and not have the funds to complete it.
 
New here, not necessarily new to solar. I previously lived in Ohio and permitting in my city/county were far more homeowner friendly than in South Carolina where I live now.

I installed a 8kw roof mounted system as the homeowner, got all the permits myself, and passed all the inspections. Submitted everything to the power company and got onto net metering.

Can't really do that here. Im kind of in an unincorporated area serviced by duke who does net metering but the city my mailing address is in requires you to be a licensed electrician to do any of that. As most of you know, this is a DIY forum and paying 4, 5? times what it costs to do yourself to have someone else do it isn't quite the spirit of this.... right?

So... what if i just forgo net metering (and in a lot of cases its starting to go away anyway...) and go hybrid with no export?

I've been eyeing EG4 12kxp and 18kxp hybrid inverters. From what I understand they look to do what I'm thinking. Initially, due to cost I'm looking to grab the inverter and panels and set all that up. As money permits I'll be adding battery capacity.

Am I understanding it correctly that the 12/18k hybrid inverters will (with CT clamps on the mains) produce only what is needed in the house and send the rest to battery (once I have battery)? And the grid can be fed in via breaker (as is typical in grid-tie setups) and will supplement power produced by solar as needed?

The goal may eventually be to have enough battery to possibly give up having utility power but that's down the road. The grid tie would remain for a while why the entire system is built out. Over time I'd suspect I'd need a second inverter to be fully off grid - it's a big house with 2 heat pumps both with emergency resistive heating (10kw and 7kw + 3 and 3.5 ton condensing units).

I've looked at sol-ark too, looks great but seems to be double the price of the eg4 stuff

1) Zero eport is an industry-wide term that really means zeroish export. It isn't true zero export.
2) Even if the hybrid was perfect with zero export, it is still operating in a grid interactive mode and technically requires an interconnect agreement with the POCO.
3) The 18Kpv and 12Kpv have a setting that turns it into an off-grid inverter.
4) Rather than paying for a hybrid inverter, and turning it into an Off-grid inverter, you might be better off starting with an off-grid inverter like the 12000XP.
 
1) Zero eport is an industry-wide term that really means zeroish export. It isn't true zero export.
2) Even if the hybrid was perfect with zero export, it is still operating in a grid interactive mode and technically requires an interconnect agreement with the POCO.
3) The 18Kpv and 12Kpv have a setting that turns it into an off-grid inverter.
4) Rather than paying for a hybrid inverter, and turning it into an Off-grid inverter, you might be better off starting with an off-grid inverter like the 12000XP.
Thanks for the info there.
A couple questions -
If going the XP route instead do you basically re-route the grid input from the service panel to the XP and then from the XP back into the main panel?

Do you then have the option to not charge batteries from grid? The idea of course being that you want to use grid input as little as possible.

Are batteries necessary right away on the XP? Obviously not ideal but as money is available the first step is panels and inverter and use that to reduce day time use/cost and add batteries as funds are available.

Thanks for taking the time to answer
 
When setting up an off-grid inverter with a grid connection, it typically involves setting up a critical load panel.
1736021184659.png

Quite often people will put a bypass switch in so if the inverter fails or needs servicing they can keep the lights on.

1736021510642.png

The important thing to note is that as far as the utility is concerned, the off grid inverter is just another load. Power never goes back to the main panel or grid.

One reason you might want to use an 18Kpv in Offgrid mode is that it has 200A passthrough and that allows for putting the inverter before the main panel

1736021728659.png

However, there must be service entrance-rated gear with a utility disconnect and Service entrance-rated breaker between the 18Kpv and the grid. What the requirements are for this tend to vary by utility. Where I am, the main breaker on my main panel meets the requirement. Other locals have requirements for the big ugly knife switches that can be visually inspected to see the actual disconnect.

If you can use whatever gear is already there, it is a big plus because you can use that to disconnect from the grid while wiring up the system. If you have to replace the disconnect, it is going to involve changing out the existing utility disconnect, you will have to get the POCO out to pull the meter while you make the change. That is going to invite questions you probably don't want.

BTW: Most people put a bypass into this type of setup as well.

1736022334473.png
 
That is an excellent point
When setting up an off-grid inverter with a grid connection, it typically involves setting up a critical load panel.
View attachment 267758

Quite often people will put a bypass switch in so if the inverter fails or needs servicing they can keep the lights on.

View attachment 267760

The important thing to note is that as far as the utility is concerned, the off grid inverter is just another load. Power never goes back to the main panel or grid.

One reason you might want to use an 18Kpv in Offgrid mode is that it has 200A passthrough and that allows for putting the inverter before the main panel

View attachment 267762

However, there must be service entrance-rated gear with a utility disconnect and Service entrance-rated breaker between the 18Kpv and the grid. What the requirements are for this tend to vary by utility. Where I am, the main breaker on my main panel meets the requirement. Other locals have requirements for the big ugly knife switches that can be visually inspected to see the actual disconnect.

If you can use whatever gear is already there, it is a big plus because you can use that to disconnect from the grid while wiring up the system. If you have to replace the disconnect, it is going to involve changing out the existing utility disconnect, you will have to get the POCO out to pull the meter while you make the change. That is going to invite questions you probably don't want.

BTW: Most people put a bypass into this type of setup as well.

View attachment 267766
That is an excellent point about the 18k having a 200a breaker. On and off all day I've been thinking about is 100a enough just in case and should I move the two emergency heat circuits to a new panel and use the smart load of the 12x to feed it. So, thank you for pointing that out!

There's a disco in the combo outside meter box and breakers in the main panel. . I'd figure on following code anyway with an AC disconnect and RSS button however your point about the disconnect makes adding another seem a bit unnecessary.

I appreciate you bringing that up, thank you
 
The electric muni here limits grid-tie solar to 100% of last 12 months of bills. Hence from FOIA requests average system size in their territory (46K total customers, maybe 400 PV) is 5KW. I've had a couple systems in town actually go off-grid (i.e. pull the meter) in order to size larger. I ran for one, OpenSolar with their bills only a 3.2KW (100%), had roof space for 7KW. I've got more asking about having the best of both worlds (i.e. off-grid with grid connection) using manual/ATS. Muni rules you can as long as ATS does "non-parallel mode or open transition". Looking for a "reasonable" 100A/200A ATS (not a $2500 Socomec, or generator focus Kohler/Generac and not a $50 Chinese) with a remote control function. Thanks! Sorry if wrong forum to post in.
 

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