True zero export with Sol Ark 15K wired as whole home generator?

[J.Midi]

Hi All- I've been lurking for a while as I've planned out a solar install for small farmhouse in the mid-west that is really only used in the summer months. Initially I was planning to do a grid-tie with interconnect sometime in 2026 but I'd like to take advantage of the tax credit and don't think I can get all that approved and installed before December. Also- Evergy only pays wholesale (like 2 cents) for excess generation and trues-up every month. So it's not like I can generate excess when the house is not occupied and use it in the summer. So my focus changed to a zero-export system BUT leakage is still possible and I do have a smart meter from Evergy on my pole and I'm just going to assume the utility will notice any small leakage. I understand I can configure a Sol-Ark to minimize the chance of leakage but it still can happen and the config that minimizes it the most seems to just have solar to the critical loads (and batteries) and that's sub-optimal.

I really only need a 5KW system and even that would be excess in the winter by a few kwh per day, so I was thinking a Sol-ark 8K, but if I'm reading everything correctly and I use a Sol-Ark 15K then I get 200AMP passthrough and I can wire from the grid to my Sol-Ark to my main panel and that makes everything very clean and can be configured for no leakage if I don't sell back to grid. Grid->Disconnect->Sol-Ark->main panel. I would ground mount 10 440 to 500 watt panels.

I don't have to worry about picking critical loads and if I understand correctly if I don't set it up to sell back to the grid then it won't leak or spike to the grid. Is this assumption correct? It looks like moving from an 8K to a 15K unit extends my ROI by 15 months and that seems worthwhile to me. And actually if it's the difference between getting the 30% credit or not then it's positive to my ROI.

I'd have 2 48V 100Ah batteries in the solution and do everything with UL components so if I did want to do an interconnect then I could.

Any thoughts/advice greatly appreciated. What should I consider besides Sol-Ark? Everything else I've been able to find seems to have more components or more trade-offs than dropping a Sol-Ark 15K in.

 

[DIYrich]

I would do the 15k. But, add more batteries. Run it grid disconnected to eliminate backfeed. Connect to grid when you need to charge the battery from the grid.

Midnite solar is worth considering.

Or consider an off grid system, like growatt or eg4 12000xp. They can charge from the grid.

 

[J.Midi]

I would do the 15k. But, add more batteries. Run it grid disconnected to eliminate backfeed. Connect to grid when you need to charge the battery from the grid.

Midnite solar is worth considering.

Or consider an off grid system, like growatt or eg4 12000xp. They can charge from the grid.

thank you for the feedback. I thought about more batteries and "Utility Be Damned" but not sure I'm ready for that. Really wanted to start with something like this and then grow into completely off-grid.

Question on off-grid: when the same situation happens that would leak power back to the grid in grid-tie what happens in an off-grid scenario? Where does the power go?

Also, in the grid-tie with battery zero-export scenario is there only risk of leakage if the batteries are not full? In other words will the 'leakage' go to the batteries first if SoC allows it?

 

[TechRider]

I played around with zero export while waiting on my interconnect to be approved with my 15k. I couldn't get it, no matter the settings. That was with 90kWh worth of batteries attached. I averaged about 1 kWh / month according to Solar-Assistant. At my peak, I had my zero export set at 500w and while it did help, it didn't get rid of it.

What some people do is hook their utility up to a chargeverter and charge the batteries from the grid when needed. You don't get any of the benefits of grid connected that way but you get zero export.

I'd suggest putting at least a small battery on. You can run small loads in the evening and get closer to the off-grid feel.


Question on off-grid: when the same situation happens that would leak power back to the grid in grid-tie what happens in an off-grid scenario? Where does the power go? - I think the inverter operates a little differently, it doesn't have to sync with the grid so it's responsible for everything. The biggest leaks seem to be when you have something pulling a bunch of power then it suddenly stops. When you're grid connected, the inverter doesn't have to deal with that surge so it lets it flow through. Off grid, it deals with it.

Also, in the grid-tie with battery zero-export scenario is there only risk of leakage if the batteries are not full? In other words will the 'leakage' go to the batteries first if SoC allows it? - Nope, same as above. I've seen my system surge 2-3kW out to the grid while my batteries are below 30%. It's very brief and I'm taking the UI's word for it.

 

[SunDave]

I have a 15k and have been very happy with it. The 200amp passthrough is handy for not having to re-wire everything. I now have a grid-sell setup, but I think unless the grid is disconnected, there is some chance of leakage.

There are off-grid inverters that won't back feed, but I'm not aware of any with a 200 amp passthrough. Hybrid inverters are a different animal from off-grid inverters. From what I have seen, they are great for grid tied\sell scenarios, and even off-grid, but not designed for on-grid without an interconnect agreement.

 

[J.Midi]

I played around with zero export while waiting on my interconnect to be approved with my 15k. I couldn't get it, no matter the settings. That was with 90kWh worth of batteries attached. I averaged about 1 kWh / month according to Solar-Assistant. At my peak, I had my zero export set at 500w and while it did help, it didn't get rid of it.

What some people do is hook their utility up to a chargeverter and charge the batteries from the grid when needed. You don't get any of the benefits of grid connected that way but you get zero export.

I'd suggest putting at least a small battery on. You can run small loads in the evening and get closer to the off-grid feel.


Question on off-grid: when the same situation happens that would leak power back to the grid in grid-tie what happens in an off-grid scenario? Where does the power go? - I think the inverter operates a little differently, it doesn't have to sync with the grid so it's responsible for everything. The biggest leaks seem to be when you have something pulling a bunch of power then it suddenly stops. When you're grid connected, the inverter doesn't have to deal with that surge so it lets it flow through. Off grid, it deals with it.

Also, in the grid-tie with battery zero-export scenario is there only risk of leakage if the batteries are not full? In other words will the 'leakage' go to the batteries first if SoC allows it? - Nope, same as above. I've seen my system surge 2-3kW out to the grid while my batteries are below 30%. It's very brief and I'm taking the UI's word for it.

Thanks for this info. Nice to see someone tried to game the system like I wanted to and know their results. I saw a few threads about chargeverter and haven't dug into it yet. I guess I can always submit my plans knowing I'm using all UL products and not have to worry about anything getting rejected and in the mean time set it all up and charge the batteries to show it's all working and document it in the very small chance the IRS asks any questions.

 

[1201]

Get the equipment you need this year and permit it next year.

there are much cheaper options than solark that have the same quality.

 

[TechRider]

The chargeverter is quite simple, it's just an AC to DC battery charger - one way. From what I've seen, you could set it so it would automatically come on at a certain voltage. You'd be in an off grid setup with supplementary battery charging. The only downside is if you need to draw a load larger than what the 15k could handle, you don't get help. On the flip side, there is zero export to the grid that way.

If I had to re-do my setup, that's one thing I'd probably change. I have my generator on an ATS and I left that in place. If I had the extra space, I would have wired it to a couple chargeverters so I didn't have to worry about the power it puts out. So far, its only run to exercise itself monthly.

Now that I've been installed 1.25 years, I've seen about 3-4 times where I've pulled more than my 15k could provide but only by 2-3kw. I've gotten real close to the limit a few more times than that.

 

[SunDave]

It's all going to depend on your power company and if they watch things closely. I had a 15k and 30kW of batteries with small solar setup for about a year before I did a grid tie agreement for a larger solar install. Nearly zeroed out one of two meters. I was never asked about it. When I called to figure out the grid tie agreement they said, "oh, yeah that should have had an agreement, but no big deal".

I suspect my power co was extremely lenient in that regard vs. most of them.